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	Author	Baselmans, J.; Kooi, J.; Baryshev, A.; Yang, Z. Q.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.; Voronov, B.; Gol’tsman, G.
	Title	Full characterization of small volume NbN HEB mixers for space applications			Type	Conference Article
	Year	2005	Publication	Proc. 16^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 16^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	457-462
	Keywords	NbN HEB mixers
	Abstract	NbN phonon cooled HEB’s are one of the most promising bolometer mixer technologies for (near) future (space) applications. Their performance is usually quantified by mea- suring the receiver noise temperature at a given IF frequency, usually around 1 – 2 GHz. However, for any real applications it is vital that one fully knows all the relevant properties of the mixer, including LO power, stability, direct detection, gain bandwidth and noise bandwidth, not only the noise temperature at low IF frequencies. To this aim we have measured all these parameters at the optimal operating point of one single, small volume quasioptical NbN HEB mixer. We find a minimum noise temperature of 900 K at 1.46 THz. We observe a direct detection effect indicated by a change in bias current when changing from a 300 K hot load to a 77 K cold load. Due to this effect we overestimate the noise temperature by about 22% using a 300 K hot load and a 77 K cold load. The LO power needed to reach the optimal operating point is 80 nW at the receiver lens front, 59 nW inside the NbN bridge. However, using the isothermal technique we find a power absorbed in the NbN bridge of 25 nW, a difference of about a factor 2. We obtain a gain bandwidth of 2.3 GHz and a noise bandwidth of 4 GHz. The system Allan time is about 1 sec. in a 50 MHz spectral bandwidth and a deviation from white noise integration (governed by the radiometer equation) occurs at 0.2 sec., which implies a maximum integration time of a few seconds in a 1 MHz bandwidth spectrometer.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Göteborg, Sweden	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	363
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	Author	Finkel, M. I.; Maslennikov, S. N.; Vachtomin, Yu. B.; Svechnikov, S. I.; Smirnov, K. V.; Seleznev, V. A.; Korotetskaya, Yu. P.; Kaurova, N. S.; Voronov, B. M.; Gol'tsman, G. N.
	Title	Hot electron bolometer mixer for 20 – 40 THz frequency range			Type	Conference Article
	Year	2005	Publication	Proc. 16^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 16^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	393-397
	Keywords	IR NbN HEB mixers
	Abstract	The developed HEB mixer was based on a 5 nm thick NbN film deposited on a GaAs substrate. The active area of the film was patterned as a 30×20 μm 2 strip and coupled with a 50 Ohm coplanar line deposited in situ. An extended hemispherical germanium lens was used to focus the LO radiation on the mixer. The responsivity of the mixer was measured in a direct detection mode in the 25÷64 THz frequency range. The noise performance of the mixer and the directivity of the receiver were investigated in a heterodyne mode. A 10.6 μm wavelength CW CO 2 laser was utilized as a local oscillator.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Göteborg, Sweden	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	369
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	Author	Loudkov, D.; Tong, C. Y. E.; Blundell, R.; Kaurova, N.; Grishina, E.; Voronov, B.; Gol'tsman, G.
	Title	An investigation of the performance of the superconducting HEB슠mixer as a function of its RF슠embedding impedance			Type	Journal Article
	Year	2005	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal
	Volume	15	Issue	2	Pages	472-475
	Keywords	HEB mixer
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	IEEE	Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	371
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	Author	Gol'tsman, Gregory N.; Vachtomin, Yuriy B.; Antipov, Sergey V.; Finkel, Matvey I.; Maslennikov, Sergey N.; Smirnov, Konstantin V.; Polyakov, Stanislav L.; Svechnikov, Sergey I.; Kaurova, Natalia S.; Grishina, Elisaveta V.; Voronov, Boris M.
	Title	NbN phonon-cooled hot-electron bolometer mixer for terahertz heterodyne receivers			Type	Conference Article
	Year	2005	Publication	Proc. SPIE	Abbreviated Journal	Proc. SPIE
	Volume	5727	Issue		Pages	95-106
	Keywords	NbN HEB mixers
	Abstract	We present the results of our studies of NbN phonon-cooled HEB mixers at terahertz frequencies. The mixers were fabricated from NbN film deposited on a high-resistivity Si substrate with an MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 x 0.2 μm2 active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. The largest gain bandwidth of 5.2 GHz was achieved for a mixer based on 2 nm thick NbN film deposited on MgO layer over Si substrate. The gain bandwidth of the mixer based on 3.5 nm NbN film deposited on Si with MgO is 4.2 GHz and the noise bandwidth for the same device amounts to 5 GHz. We also present the results of our research into decrease of the direct detection contribution to the measured Y-factor and a possible error of noise temperature calculation. The use of a square nickel cell mesh as an IR-filter enabled us to avoid the effect of direct detection and measure apparent value of the noise temperature which was 16% less than that obtained using conventional black polyethylene IR-filter.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference	Terahertz and Gigahertz Electronics and Photonics IV
	Notes				Approved	no
	Call Number				Serial	378
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	Author	Maslennikov, S. N.; Finkel, M. I.; Antipov, S. V.; Polyakov, S. L.; Zhang, W.; Ozhegov, R.; Vachtomin, Yu. B.; Svechnikov, S. I.; Smirnov, K. V.; Korotetskaya, Yu. P.; Kaurova, N. S.; Gol'tsman, G. N.; Voronov, B. M.
	Title	Spiral antenna coupled and directly coupled NbN HEB mixers in the frequency range from 1 to 70 THz			Type	Conference Article
	Year	2006	Publication	Proc. 17^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 17^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	177-179
	Keywords	directly coupled NbN HEB mixers
	Abstract	We investigate both antenna coupled and directly coupled HEB mixers at several LO frequencies within the range of 2.5 THz to 70 THz. H20 (2.5+10.7 THz), and CO2 (30 THz) gas discharge lasers are used as the local oscillators. The noise temperature of antenna coupled mixers is measured at LO frequencies of 2.5 THz, 3.8 THz, and 30 THz. The results for both antenna coupled and directly coupled mixer types are compared. The devices with in—plane dimensions of 5x5 ,um 2 are pumped by LO radiation at 10.7 THz. The directly coupled HEB demonstrates nearly flat dependence of responsivity on frequency in the range of 25+64 THz.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Paris, France	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	386
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	Author	Gershenzon, E. M.; Gol'tsman, G. N.; Gogidze, I. G.; Gusev, Yu. P.; Elantiev, A. I.; Karasik, B. S.; Semenov, A. D.
	Title	Millimeter and submillimeter wave range mixer based on electronic heating of superconducting films in the resistive state			Type	Journal Article
	Year	1990	Publication	Sov. Supercond.	Abbreviated Journal	Sov. Supercond.
	Volume	3	Issue	10	Pages	1582-1597
	Keywords	HEB mixers
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	240
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	Author	Prober, D. E.
	Title	Superconducting terahertz mixer using a transition-edge microbolometer			Type	Journal Article
	Year	1993	Publication	Appl. Phys. Lett.	Abbreviated Journal	Appl. Phys. Lett.
	Volume	62	Issue	17	Pages	2119-2121
	Keywords	HEB mixer, NbN, TES
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes	Recommended by Klapwijk			Approved	no
	Call Number				Serial	244
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	Author	Hans Ekstrom; Karasik, Boris S.; Kollberg, Erik L.; Sigfrid Yngvesson
	Title	Conversion gain and noise of niobium superconducting hot–electron–mixers			Type	Journal Article
	Year	1995	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal
	Volume	43	Issue	4	Pages	938-947
	Keywords	Nb HEB mixers
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	254
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	Author	Karasik, B. S.; Elantiev, A. I.
	Title	Analysis of the noise performance of a hot-electron superconducting bolometer mixer			Type	Conference Article
	Year	1995	Publication	Proc. 6^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 6^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	229-246
	Keywords	HEB mixers
	Abstract	A theoretical analysis for the noise temperature of hot–electron superconducting mixer has been presented. Thecontributions of both Johnson noise and electron temperature fluctuations have been evaluated. A set of criteriaensuring low noise performance of the mixer has been stated and a simple analytic expression for the noisetemperature of the mixer device has been suggested. It has been shown that an improvement of the mixer sensitivitydoes not necessarily follow by a decrease of the bandwidth. An SSB noise temperature limit due to the intrinsic noisemechanisms has been estimated to be as low as 40–90 K for a mixer device made from Nb or NbN thin film.Furthermore, the conversion gain bandwidth can be as wide as is allowed by the intrinsic electron temperaturerelaxation time if an appropriate choice of the mixer resistance has been made. The intrinsic mixer noise bandwidthis of 3 GHz for Nb device and of 5 GHz for NbN device. An additional improvement of the theory has been madewhen a distinction between the impedance measured at high intermediate frequency (larger than the mixerbandwidth) and the mixer ohmic resistance has been taken into account.Recently obtained experimental data on Nb and NbNbolometer mixer devices are viewed in connection with thetheoretical predictions.The noise temperature limit has also been specified for the mixer device where an outdiffusion coolingmechanism rather than the electron–phonon energy relaxation determines the mixer bandwidth. A consideration ofthe noise performance of a bolometer mixer made from YBaCuO film utilizing a hot–electron effect has been done.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Pasadena, Ca	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	258
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	Author	Yagubov, P.; Gol'tsman, G.; Voronov, B.; Seidman, L.; Siomash, V.; Cherednichenko, S.; Gershenzon, E.
	Title	The bandwidth of HEB mixers employing ultrathin NbN films on sapphire substrate			Type	Conference Article
	Year	1996	Publication	Proc. 7^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 7^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	290-302
	Keywords	NbN HEB mixers, fabrication process
	Abstract	We report on some unusual features observed during fabrication of ultrathin NbN films with high Tc. The films were used to fabricate HEB mixers, which were evaluated for IF bandwidth measurements at 140 GHz. Ultrathin films were fabricated using reactive dc magnetron sputtering with a discharge current source. Reproducible parameters of the films are assured keeping constant the difference between the discharge voltage in pure argon, and in a gas mixture, for the same current. A maximum bandwidth of 4 GHz at optimal LO and dc bias was obtained for mixer chip based on NbN film 35 A thick with Tc = 11 K.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Charlottesville, Virginia, USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	266
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	Author	Semenov, Alexei; Richter, Heiko; Smirnov, Konstantin; Voronov, Boris; Gol'tsman, Gregory; Hübers, Heinz-Wilhelm
	Title	The development of terahertz superconducting hot-electron bolometric mixers			Type	Journal Article
	Year	2004	Publication	Supercond. Sci. Technol.	Abbreviated Journal	Supercond. Sci. Technol.
	Volume	17	Issue	5	Pages	436-439
	Keywords	NbN HEB mixers
	Abstract	We present recent advances in the development of NbN hot-electron bolometric (HEB) mixers for flying terahertz heterodyne receivers. Three important issues have been addressed: the quality of the source NbN films, the effect of the bolometer size on the spectral properties of different planar feed antennas, and the local oscillator (LO) power required for optimal operation of the mixer. Studies of the NbN films with an atomic force microscope indicated a surface structure that may affect the performance of the smallest mixers. Measured spectral gain and noise temperature suggest that at frequencies above 2.5 THz the spiral feed provides better overall performance than the double-slot feed. Direct measurements of the optimal LO power support earlier estimates made in the framework of the uniform mixer model.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	357
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	Author	Cherednichenko, S.; Yagoubov, P.; Il'In, K.; Gol'tsman, G.; Gershenzon, E.
	Title	Large bandwidth of NbN phonon-cooled hot-electron bolometer mixers on sapphire substrates			Type	Conference Article
	Year	1997	Publication	Proc. 8^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 8^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	245-257
	Keywords	NbN HEB mixers, fabrication process
	Abstract	The bandwidth of NbN phonon-cooled hot electron bolometer mixers has been systematically investigated with respect to the film thickness and film quality variation. The films, 2.5 to 10 mm thick, were fabricated on sapphire substrates using DC reactive magnetron sputtering. All devices consisted of several parallel strips, each 1 1.1 wide and 211 long, placed between Ti-Au contact pads. To measure the gain bandwidth we used two identical BWOs operating in the 120-140 GHz frequency range, one functioning as a local oscillator and the other as a signal source. The majority of the measurements were made at an ambient temperature of 4.5 K with optimal LO and DC bias. The maximum 3 dB bandwidth (about 4 GHz) was achieved for the devices made of films which were 2.5-3.5 nm thick, had a high critical temperature, and high critical current density. A theoretical analysis of bandwidth for these mixers based on the two-temperature model gives a good description of the experimental results if one assumes that the electron temperature is equal to the critical temperature.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	276
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	Author	Kawamura, J.; Blundell, R.; Tong, C-Y. E.; Gol'tsman, G.; Gershenzon, E.; Voronov, B.; Cherednichenko, S.
	Title	Phonon-cooled NbN HEB mixers for submillimeter wavelengths			Type	Conference Article
	Year	1997	Publication	Proc. 8^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 8^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	23-28
	Keywords	waveguide NbN HEB mixers
	Abstract	The noise performance of receivers incorporating NbN phonon-cooled superconducting hot electron bolometric mixers is measured from 200 GHz to 900 GHz. The mixer elements are thin-film (thickness — 4 nm) NbN with —5 to 40 pm area fabricated on crystalline quartz sub- strates. The receiver noise temperature from 200 GHz to 900 GHz demonstrates no unexpected degradation with increasing frequency, being roughly TRx ,; 1-2 K The best receiver noise temperatures are 410 K (DSB) at 430 GHz, 483 K at 636 GHz, and 1150 K at 800 GHz.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	275
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	Author	Ekstörm, H.; Kollberg, E.; Yagoubov, P.; Gol'tsman, G.; Gershenzon, E.; Yngvesson, S.
	Title	Gain and noise bandwidth of NbN hot-electron bolometric mixers			Type	Journal Article
	Year	1997	Publication	Appl. Phys. Lett.	Abbreviated Journal	Appl. Phys. Lett.
	Volume	70	Issue	24	Pages	3296-3298
	Keywords	NbN HEB mixers, conversion loss, conversion gain, U-factor technique
	Abstract	We have measured the noise performance and gain bandwidth of 35 Å thin NbN hot-electron mixers integrated with spiral antennas on silicon substrate lenses at 620 GHz. The best double-sideband receiver noise temperature is less than 1300 K with a 3 dB bandwidth of ≈5 GHz. The gain bandwidth is 3.2 GHz. The mixer output noise dominated by thermal fluctuations is 50 K, and the intrinsic conversion gain is about −12 dB. Without mismatch losses and excluding the loss from the beamsplitter, we expect to achieve a receiver noise temperature of less than 700 K.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	279
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	Author	Merkel, H. F.; Yagoubov, P. A.; Kroug, M.; Khosropanah, P.; Kollberg, E. L.; Gol’tsman, G. N.; Gershenzon, E. M.
	Title	Noise temperature and absorbed LO power measurement methods for NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies			Type	Conference Article
	Year	1998	Publication	Proc. 28th European Microwave Conf.	Abbreviated Journal	Proc. 28th European Microwave Conf.
	Volume	1	Issue		Pages	294-299
	Keywords	NbN HEB mixers
	Abstract	In this paper the absorbed LO power requirements and the noise performance of NbN based phonon-cooled hot electron bolometric (HEB) quasioptical mixers are investigated for RF frequencies in the 0.55-1.1 range The minimal measured DSB noise temperatures are about 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz and 1250 K at 1.1 THz. The increase in noise temperature at 1.1THz is attributed to water absorption. The absorbed LO power is measured using a calorimetric approach. The results are subsequently corrected for lattice heating. These values are compared to results of a novel one dimensional hot spot mixer models and to a more traditional isotherm method which tends to underestimate the absorbed LO power for small bias powers. Typically a LO power between 50nW and 100nW is needed to pump the device to the optimal operating point.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference	28th European Microwave Conference
	Notes				Approved	no
	Call Number				Serial	1580
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	Author	Gerecht, E.; Musante, C. F.; Jian, H.; Yngvesson, K. S.; Dickinson, J.; Waldman, J.; Gol'tsman, G. N.; Yagoubov, P. A.; Voronov, B. M.; Gershenzon, E. M.
	Title	Measured results for NbN phonon-cooled hot electron bolometric mixers at 0.6-0.75 THz, 1.56 THz, and 2.5 THz			Type	Conference Article
	Year	1998	Publication	Proc. 9^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 9^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	105-114
	Keywords	NbN HEB mixers
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	1587
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	Author	Schubert, J.; Semenov, A.; Gol'tsman, G.; Hübers, H.-W.; Schwaab, G.; Voronov, B.; Gershenzon, E.
	Title	Noise temperature of an NbN hot-electron bolometric mixer at frequencies from 0.7 THz to 5.2 THz			Type	Journal Article
	Year	1999	Publication	Supercond. Sci. Technol.	Abbreviated Journal
	Volume	12	Issue	11	Pages	748-750
	Keywords	NbN HEB mixers
	Abstract	We report on noise temperature measurements of an NbN phonon-cooled hot-electron bolometric mixer in the terahertz frequency range. The devices were 3 nm thick films with in-plane dimensions 1.7 × 0.2 µm2 and 0.9 × 0.2 µm2 integrated in a complementary logarithmic-spiral antenna. Measurements were performed at seven frequencies ranging from 0.7 THz to 5.2 THz. The measured DSB noise temperatures are 1500 K (0.7 THz), 2200 K (1.4 THz), 2600 K (1.6 THz), 2900 K (2.5 THz), 4000 K (3.1 THz), 5600 K (4.3 THz) and 8800 K (5.2 THz).
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	298
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	Author	Tong, C.-Y. Edward; Kawamura, Jonathan; Todd, R. Hunter; Papa, D. Cosmo; Blundell, Raymond.; Smith, Michael; Patt, Ferdinand; Gol'tsman, Gregory; Gershenzon, Eugene
	Title	Successful operation of a 1 THz NbN hot-electron bolometer receiver			Type	Conference Article
	Year	2000	Publication	Proc. 11^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 11^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	49-59
	Keywords	NbN HEB mixers, applications
	Abstract	A phonon-cooled NbN superconductive hot-electron bolometer receiver covering the frequency range 0.8-1.04 THz has successfully been used for astronomical observation at the Sub-Millimeter Telescope Observatory on Mount Graham, Arizona. This waveguide heterodyne receiver is a modified version of our fixed-tuned 800 GHz HEB receiver to allow for operation beyond 1 THz. The measured noise temperature of this receiver is about 1250 K at 0.81 THz, 560 K at 0.84 THz, and 1600 K at 1.035 THz. It has a 1 GHz wide IF bandwidth, centered at 1.8 GHz. This receiver has recently been used to detect the CO (9-8) molecular line emission at 1.037 THz in the Orion nebula. This is the first time a ground-based heterodyne receiver has been used to detect a celestial source above 1 THz.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	303
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	Author	Semenov, A. D.; Hübers, H.–W.; Schubert, J.; Gol'tsman, G. N.; Elantiev, A. I.; Voronov, B. M.; Gershenzon, E. M.
	Title	Frequency dependent noise temperature of the lattice cooled hot-electron terahertz mixer			Type	Conference Article
	Year	2000	Publication	Proc. 11^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 11^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	39-48
	Keywords	NbN HEB mixers
	Abstract	We present the measurements and the theoretical model on the frequency dependent noise temperature of a lattice cooled hot electron bolometer (HEB) mixer in the terahertz frequency range. The experimentally observed increase of the noise temperature with frequency is a cumulative effect of the non-uniform distribution of the high frequency current in the bolometer and the charge imbalance, which occurs near the edges of the normal domain and contacts with normal metal. In addition, we present experimental results which show that the noise temperature of a HEB mixer can be reduced by about 30% due to a Parylene antireflection coating on the Silicon hyperhemispheric lens.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	305
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	Author	Khosropanah, P.; Gao, J. R.; Laauwen, W. M.; Hajenius, M; Klapwijk, T. M.
	Title	Low noise NbN hot electron bolometer mixer at 4.3 THz			Type	Journal Article
	Year	2007	Publication	Appl. Phys. Lett.	Abbreviated Journal	Appl. Phys. Lett.
	Volume	91	Issue		Pages	221111 (1 to 3)
	Keywords	NbN HEB mixers, NbN, contacts cleaning
	Abstract	We have studied the sensitivity of a superconducting NbN hot electron bolometer mixer integrated with a spiral antenna at 4.3 THz. Using hot/cold blackbody loads and a beam splitter all in vacuum, we measured a double sideband receiver noise temperature of 1300 K at the optimum local oscillator (LO) power of 330 nW, which is about 12 times the quantum noise (hnu/2kB). Our result indicates that there is no sign of degradation of the mixing process at the superterahertz frequencies. Moreover, a measurement method is introduced which allows us for an accurate determination of the sensitivity despite LO power fluctuations.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	584
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	Author	Kroug, M.; Cherednichenko, S.; Merkel, H.; Kollberg, E.; Voronov, B.; Gol'tsman, G.; Hübers, H. W.; Richter, H.
	Title	NbN hot electron bolometric mixers for terahertz receivers			Type	Journal Article
	Year	2001	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal	IEEE Trans. Appl. Supercond.
	Volume	11	Issue	1	Pages	962-965
	Keywords	NbN HEB mixers
	Abstract	Sensitivity and gain bandwidth measurements of phonon-cooled NbN superconducting hot-electron bolometer mixers are presented. The best receiver noise temperatures are: 700 K at 1.6 THz and 1100 K at 2.5 THz. Parylene as an antireflection coating on silicon has been investigated and used in the optics of the receiver. The dependence of the mixer gain bandwidth (GBW) on the bias voltage has been measured. Starting from low bias voltages, close to operating conditions yielding the lowest noise temperature, the GBW increases towards higher bias voltages, up to three times the initial value. The highest measured GBW is 9 GHz within the same bias range the noise temperature increases by a factor of two.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	312
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	Author	Cherednichenko, S.; Kroug, M.; Merkel, H.; Kollberg, E.; Loudkov, D.; Smirnov, K.; Voronov, B.; Gol'tsman, G.; Gershenzon, E.
	Title	Local oscillator power requirement and saturation effects in NbN HEB mixers			Type	Conference Article
	Year	2001	Publication	Proc. 12^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 12^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	273-285
	Keywords	NbN HEB mixers, LO power, local oscillator power, saturation effect, dynamic range
	Abstract	The local oscillator power required for NbN hot-electron bolometric mixers (P LO ) was investigated with respect to mixer size, critical temperature and ambient temperature. P LO can be decreased by a factor of 10 as the mixer size decreases from 4×0.4 µm 2 to 0.6×0.13 µm 2 . For the smallest volume mixer the optimal local oscillator power was found to be 15 nW. We found that for such mixer no signal compression was observed up to an input signal of 2 nW which corresponds to an equivalent input load of 20,000 K. For a constant mixer volume, reduction of T c can decrease optimal local oscillator power at least by a factor of 2 without a deterioration of the receiver noise temperature. Bath temperature was found to have minor effect on the receiver characteristics.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	San Diego, CA, USA	Editor	Jet Propulsion Laboratory, California Inst.it.u.t.e of Technology
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	318
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	Author	Kroug, M.; Cherednichenko, S.; Choumas, M.; Merkel, H.; Kollberg, E.; Hübers, H.-W.; Richter, H.; Loudkov, D.; Voronov, B.; Gol'Tsman, G.
	Title	HEB quasi-optical heterodyne receiver for THz frequencies			Type	Conference Article
	Year	2001	Publication	Proc. 12^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal
	Volume		Issue		Pages	244-252
	Keywords	HEB mixer, NbN, MgO, conversion gain bandwidth, noise temperature
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	San Diego, CA, USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	319
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	Author	Kawamura, J.; Hunter, T. R.; Tong, C. Y. E.; Blundell, R.; Papa, D. C.; Patt, F.; Peters, W.; Wilson, T.; Henkel, C.; Goltsman, G.; Gershenzon, E.
	Title	Ground-based terahertz CO spectroscopy towards Orion			Type	Journal Article
	Year	2002	Publication	A&A	Abbreviated Journal	A&A
	Volume	394	Issue	1	Pages	271-274
	Keywords	HEB mixers, applications
	Abstract	Using a superconductive hot-electron bolometer heterodyne receiver on the 10-m Heinrich Hertz Telescope on Mount Graham, Arizona, we have obtained velocity-resolved 1.037 THz CO () spectra toward several positions along the Orion Molecular Cloud (OMC-1) ridge. We confirm the general results of prior observations of high-J CO lines that show that the high temperature, , high density molecular gas, , is quite extended, found along a ~ region centered on BN/KL. However, our observations have significantly improved angular resolution, and with a beam size of we are able to spatially and kinematically discriminate the emission originating in the extended quiescent ridge from the very strong and broadened emission originating in the compact molecular outflow. The ridge emission very close to the BN/KL region appears to originate from two distinct clouds along the line of sight with and ≈ . The former component dominates the emission to the south of BN/KL and the latter to the north, with a turnover point coincident with or near BN/KL. Our evidence precludes a simple rotation of the inner ridge and lends support to a model in which there are multiple molecular clouds along the line of sight towards the Orion ridge.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	322
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	Author	Hübers, H.-W.; Semenov, A. D.; Richter, H.; Schubert, J.; Hadjiloucas, S.; Bowen, J. W.; Gol'tsman, G.; Voronov, B. M.; Gershenzon, E. M.
	Title	Antenna pattern of the quasi-optical hot-electron bolometric mixer at terahertz frequencies			Type	Conference Article
	Year	2001	Publication	Proc. 12^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 12^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	286-296
	Keywords	NbN HEB mixers
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	San Diego, CA, USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	323
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	Author	Vahtomin, Yuriy B.; Finkel, Matvey I.; Antipov, Sergey V.; Voronov, Boris M.; Smirnov, Konstantin V.; Kaurova, Natalia S.; Drakinski, Vladimir N.; Gol'tsman, Gregogy N.
	Title	Gain bandwidth of phonon-cooled HEB mixer made of NbN thin film with MgO buffer layer on Si			Type	Conference Article
	Year	2002	Publication	Proc. 13^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 13^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	259-270
	Keywords	NbN HEB mixers, conversion gain bandwidth
	Abstract	We present recently obtained values for gain bandwidth of NbN HEB mixers for different substrates and film thicknesses and for MgO buffer layer on Si at LO frequency of 0.85-1 THz. The maximal bandwidth, 5.2 GHz, was achieved for the device on MgO buffer layer on Si with a 2 nm thick NbN film. Functional devices based on NbN films of such thickness were fabricated for the first time due to an improvement of superconducting properties of NbN film deposited on MgO buffer layer on Si substrate.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge, MA, USA	Editor	Harvard university
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	325
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	Author	Meledin, D.; Tong, C. Y.-E.; Blundell, R.; Kaurova, N.; Smirnov, K.; Voronov, B.; Gol'tsman, G.
	Title	The sensitivity and IF bandwidth of waveguide NbN hot electron bolometer mixers on MgO buffer layers over crystalline quartz			Type	Conference Article
	Year	2002	Publication	Proc. 13^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 13^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	65-72
	Keywords	waveguide NbN HEB mixers
	Abstract	We have developed and characterized waveguide phonon-cooled NbN Hot Electron Bolometer (FMB) mixers fabricated from a 3-4 nm thick NbN film deposited on a 200nm thick MgO buffer layer over crystalline quartz. Double side band receiver noise temperatures of 900-1050 K at 1.035 THz, and 1300-1400 K at 1.26 THz have been measured at an intermediate frequency of 1.5 GHz. The intermediate frequency bandwidth, measured at 0.8 THz LO frequency, is 3.2 GHz at the optimal bias point for low noise receiver operation.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge, MA, USA	Editor	Harvard university
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	326
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	Author	Cherednichenko, S.; Kroug, M.; Khosropanah, P.; Adam, A.; Merkel, H.; Kolberg, E.; Loudkov, D.; Voronov, B.; Gol'tsman, G.; Richter, H.; Hübers, H. W.
	Title	A broadband terahertz heterodyne receiver with an NbN HEB mixer			Type	Conference Article
	Year	2002	Publication	Proc. 13^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 13^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	85-95
	Keywords	NbN HEB mixers
	Abstract	We present a broadband and low noise heterodyne receiver for 1.4-1.7 THz designed for the Hershel Space Observatory. A phonon- cooled NbN HEB mixer was integrated with a normal metal double- slot antenna and an elliptical silicon lens. DSB receiver noise temperature Tr was measured from 1 GHz through 8GHz intermediate frequency band with 50 MHz instantaneous bandwidth. At 4.2 K bath temperature and at 1.6 THz LO frequency Tr is 800 K with the receiver noise bandwidth of 5 GHz. While at 2 K bath temperature Tr was as low as 700 K. At 0.6 THz and 1.1 THz a spiral antenna integrated NbN HEB mixer showed the receiver noise temperature 500 K and 800 K, though no antireflection coating was used in this case. Tr of 1100 K was achieved at 2.5 THz while the receiver noise bandwidth was 4 GHz.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge, MA, USA	Editor	Harward University
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	332
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	Author	Huebers, H.-W.; Semenov, A.; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Smirnov, K.; Gol’tsman, G. N.; Voronov, B. M.
	Title	Superconducting hot electron bolometer as mixer for far-infrared heterodyne receivers			Type	Conference Article
	Year	2003	Publication	Proc. SPIE	Abbreviated Journal	Proc. SPIE
	Volume	4855	Issue		Pages	395-401
	Keywords	NbN HEB mixers
	Abstract	Heterodyne receivers for applications in astronomy need quantum limited sensitivity. In instruments which are currently under development for SOFIA or Herschel superconducting hot electron bolometers (HEB) will be used to achieve this goal at frequencies above 1.4 THz. We present results of the development of a phonon-cooled NbN HEB mixer for GREAT, the German Receiver for Astronomy at Terahertz Frequencies, which will be flown aboard SOFIA. The mixer is a small superconducting bridge incorporated in a planar feed antenna and a hyperhemispherical lens. Mixers with logarithmic-spiral and double-slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 17 dB. The response of the mixer was linear up to 400 K load temperature. The performance was verified by measuring an emission line of methanol at 2.5 THz. The measured linewidth is in good agreement with the linewidth deduced from pressure broadening measurements at millimeter wavelength. The results demonstrate that the NbN HEB is very well suited as a mixer for far-infrared heterodyne receivers.
	Address
	Corporate Author				Thesis
	Publisher	SPIE	Place of Publication	Tucson, USA	Editor	Phillips, T. G.; Zmuidzinas, J.
	Language		Summary Language		Original Title
	Series Editor		Series Title	Presented at the Society of Photo-Optical Instrumentation Engineers (SPIE) Conference	Abbreviated Series Title
	Series Volume	4855	Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference	Millimeter and Submillimeter Detectors for Astronomy
	Notes				Approved	no
	Call Number				Serial	335
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	Author	Hajenius, M.; Baselmans, J. J. A.; Gao, J. R.; Klapwijk, T. M.; de Korte, P. A. J.; Voronov, B.; Gol’tsman, G.
	Title	Improved NbN phonon cooled hot electron bolometer mixers			Type	Conference Article
	Year	2003	Publication	Proc. 14^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 14^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	413-423
	Keywords	NbN HEB mixers
	Abstract	NbN phonon-cooled hot electron bolometer mixers (HEBs) have been realized with negligible contact resistance to Au pads. By adding either a 5 nm Nb or a 10 nm NbTiN layer between the Au and NbN, to preserve superconductivity in the NbN under the Au contact pad, superior noise temperatures have been obtained. Using DC I,V curves and resistive transitions in combination with process parameters we analyze the nature of these improved devices and determine interface transparencies.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Tucson, USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	337
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	Author	Tong, C.-Y. E.; Meledin, D.; Loudkov, D.; Blundell, R.; Erickson, N.; Kawamura, J.; Mehdi, I.; Gol’tsman, G.
	Title	A 1.5 THz Hot-Electron Bolometer mixer operated by a planar diode based local oscillator			Type	Conference Article
	Year	2003	Publication	IEEE MTT-S Int. Microwave Symp. Digest	Abbreviated Journal	IEEE MTT-S Int. Microwave Symp. Digest
	Volume	2	Issue		Pages	751-754
	Keywords	waveguide NbN HEB mixers
	Abstract	We have developed a 1.5 THz superconducting NbN Hot-Electron Bolometer mixer. It is operated by an all-solid-state Local Oscillator comprising of a cascade of 4 planar doublers following an MMIC based W-band power amplifier. The threshold available pump power is estimated to be 1 /spl mu/W.
	Address	Philadelphia, PA, USA
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	1516
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	Author	Meledin, D.; Tong, C. Y.-E.; Blundell, R.; Kaurova, N.; Smirnov, K.; Voronov, B.; Gol'tsman, G.
	Title	Study of the IF bandwidth of NbN HEB mixers based on crystalline quartz substrate with an MgO buffer layer			Type	Journal Article
	Year	2003	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal	IEEE Trans. Appl. Supercond.
	Volume	13	Issue	2	Pages	164-167
	Keywords	NbN HEB mixer
	Abstract	In this paper, we present the results of IF bandwidth measurements on 3-4 nm thick NbN hot electron bolometer waveguide mixers, which have been fabricated on a 200-nm thick MgO buffer layer deposited on a crystalline quartz substrate. The 3-dB IF bandwidth, measured at an LO frequency of 0.81 THz, is 3.7 GHz at the optimal bias point for low noise receiver operation. We have also made measurements of the IF dynamic impedance, which allow us to evaluate the intrinsic electron temperature relaxation time and self-heating parameters at different bias conditions.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	341
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	Author	Semenov, A. D.; Hübers, Heinz-Wilhelm; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Vachtomin, Yu. B.; Finkel, M. I.; Antipov, S. V.; Voronov, B. M.; Smirnov, K. V.; Kaurova, N. S.; Drakinski, V. N.; Gol'tsman, G. N.
	Title	Superconducting hot-electron bolometer mixer for terahertz heterodyne receivers			Type	Journal Article
	Year	2003	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal
	Volume	13	Issue	2	Pages	168-171
	Keywords	NbN HEB mixers
	Abstract	We present recent results showing the development of superconducting NbN hot-electron bolometer mixer for German receiver for astronomy at terahertz frequencies and terahertz limb sounder. The mixer is incorporated into a planar feed antenna, which has either logarithmic spiral or double-slot configuration, and backed on a silicon lens. The hybrid antenna had almost frequency independent and symmetric radiation pattern slightly broader than expected for a diffraction limited antenna. At 2.5 THz the best 2200 K double side-band receiver noise temperature was achieved across a 1 GHz intermediate frequency bandwidth centred at 1.5 GHz. For this operation regime, a receiver conversion efficiency of -17 dB was directly measured and the loss budget was evaluated. The mixer response was linear at load temperatures smaller than 400 K. Implementation of the MgO buffer layer on Si resulted in an increased 5.2 GHz gain bandwidth. The receiver was tested in the laboratory environment by measuring a methanol emission line at 2.5 THz.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	343
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	Author	Vachtomin, Y. B.; Antipov, S. V.; Maslennikov, S. N.; Smirnov, K. V.; Polyakov, S. L.; Kaurova, N. S.; Grishina, E. V.; Voronov, B. M.; Gol'tsman, G. N.
	Title	Noise temperature measurements of NbN phonon-cooled hot electron bolometer mixer at 2.5 and 3.8 THz			Type	Conference Article
	Year	2004	Publication	Proc. 15^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 15^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	236-241
	Keywords	HEB mixer, NbN, direct detection effect
	Abstract	We present the results of noise temperature measurements of NbN phonon-cooled HEB mixers based on a 3.5 nm NbN film deposited on a high-resistivity Si substrate with a 200 nm – thick MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 µm x 0.2 µm active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. We also present the results of direct detection contribution to the measured Y-factor and of a possible error of noise temperature calculation. This error was more than 8% for the mixer with in-plane dimensions of 2.4 x 0.16 µm 2 at the optimal noise temperature point. The use of a mesh filter enabled us to avoid the effect of direct detection and decrease optical losses by 0.5 dB. The paper is concluded by the investigation results of the mixer polarization response. It was shown that the polarization can differ from the circular one at 3.8 THz by more than 2 dB.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Northampton, Massachusetts, USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	344
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	Author	Antipov, S. V.; Vachtomin, Yu. B.; Maslennikov, S. N.; Smirnov, K. V.; Kaurova, N. S.; Grishina, E. V.; Voronov, B. M.; Goltsman, G. N.
	Title	Noise performance of quasioptical ultrathin NbN hot electron bolometer mixer at 2.5 and 3.8 THz			Type	Conference Article
	Year	2004	Publication	Proc. 5-th MSMW	Abbreviated Journal	Proc. 5-th MSMW
	Volume	2	Issue		Pages	592-594
	Keywords	NbN HEB mixers
	Abstract	To put space-based and airborne heterodyne instruments into operation at frequencies above 1 THz the superconducting NbN hot-electron bolometer (HEB) will be incorporated into heterodyne receiver as a mixer. At frequencies above 1.3 THz the sensitivity of the NbN HEB mixers outperform the one of the Schottky diodes and SIS-mixers, and the receiver noise temperature of the NbN HEB mixers increase with frequency. In this paper we present the results of the noise temperature measurements within one batch of NbN HEB mixers based on 3.5 mn thick superconducting NbN film grown on Si substrate with MgO buffer layer at the LO frequencies 2.5 THz and 3.8 THz.
	Address	Kharkov, Ukraine
	Corporate Author				Thesis
	Publisher		Place of Publication	Kharkov, Ukraine	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference	The Fifth International Kharkov Symposium on Physics and Engineering of Microwaves, Millimeter, and Submillimeter Waves (IEEE Cat. No.04EX828)
	Notes				Approved	no
	Call Number				Serial	351
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	Author	Baselmans, J. J. A.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.; de Korte, P. A. J.; Voronov, B.; Gol'tsman, G.
	Title	Doubling of sensitivity and bandwidth in phonon cooled hot electron bolometer mixers			Type	Journal Article
	Year	2004	Publication	Appl. Phys. Lett.	Abbreviated Journal	Appl. Phys. Lett.
	Volume	84	Issue	11	Pages	1958-1960
	Keywords	NbN HEB mixers
	Abstract	We demonstrate that the performance of NbN lattice cooled hot electron bolometer mixers depends strongly on the interface quality between the bolometer and the contact structure. We show experimentally that both the receiver noise temperature and the gain bandwidth can be improved by more than a factor of 2 by cleaning the interface and adding an additional superconducting interlayer to the contact pad. Using this we obtain a double sideband receiver noise temperature TN,DSB=950 K at 2.5 THz and 4.3 K, uncorrected for losses in the optics. At the same bias point, we obtain an IF gain bandwidth of 6 GHz.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	352
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	Author	Kaurova, N. S.; Finkel, M. I.; Maslennikov, S. N.; Vahtomin, Yu. B.; Antipov, S. V.; Smirnov, K. V.; Voronov, B. M.; Gol'tsman, G. N.; Ilyin, K. S.
	Title	Submillimeter mixer based on YBa₂Cu₃O_7-x thin film			Type	Conference Article
	Year	2004	Publication	Proc. 1-st conf. Fundamental problems of high temperature superconductivity	Abbreviated Journal
	Volume		Issue		Pages	291
	Keywords	HTS, HEB mixer
	Abstract
	Address	Moscow-Zvenigorod
	Corporate Author				Thesis
	Publisher		Place of Publication	Moscow-Zvenigorod	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	355
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	Author	Bruderer, S.; Benz, A. O.; van Dishoeck, E. F.; Melchior, M.; Doty, S. D.; van der Tak, F.; Stäuber, P.; Wampfler, S. F.; Dedes, C.; Yıldız, U. A.; Pagani, L.; Giannini, T.; de Graauw, Th.; Whyborn, N.; Teyssier, D.; Jellema, W.; Shipman, R.; Schieder, R.; Honingh, N.; Caux, E.; Bächtold, W.; Csillaghy, A.; Monstein, C.; Bachiller, R.; Baudry, A.; Benedettini, M.; Bergin, E.; Bjerkeli, P.; Blake, G. A.; Bontemps, S.; Braine, J.; Caselli, P.; Cernicharo, J.; Codella, C.; Daniel, F.; di Giorgio, A. M.; Dominik, C.; Encrenaz, P.; Fich, M.; Fuente, A.; Goicoechea, J. R.; Helmich, F.; Herczeg, G. J.; Herpin, F.; Hogerheijde, M. R.; Jacq, T.; Johnstone, D.; Jørgensen, J. K.; Kristensen, L. E.; Larsson, B.; Lis, D.; Liseau, R.; Marseille, M.; McCoey, C.; Melnick, G.; Neufeld, D.; Nisini, B.; Olberg, M.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago-García, J.; Saraceno, P.; Shipman, R.; Tafalla, M.; van Kempen, T. A.; Visser, R.; Wyrowski, F.
	Title	Herschel/HIFI detections of hydrides towards AFGL 2591. Envelope emission versus tenuous cloud absorption			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L44 (1 to 7)
	Keywords	HEB mixer applications, HIFI, Herschel
	Abstract	The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory allows the first observations of light diatomic molecules at high spectral resolution and in multiple transitions. Here, we report deep integrations using HIFI in different lines of hydrides towards the high-mass star forming region AFGL 2591. Detected are CH, CH+, NH, OH+, H2O+, while NH+ and SH+ have not been detected. All molecules except for CH and CH+ are seen in absorption with low excitation temperatures and at velocities different from the systemic velocity of the protostellar envelope. Surprisingly, the CH(JF,P = 3/22,- – 1/21,+ ) and CH+(J = 1–0, J = 2–1) lines are detected in emission at the systemic velocity. We can assign the absorption features to a foreground cloud and an outflow lobe, while the CH and CH+ emission stems from the envelope. The observed abundance and excitation of CH and CH+ can be explained in the scenario of FUV irradiated outflow walls, where a cavity etched out by the outflow allows protostellar FUV photons to irradiate and heat the envelope at larger distances driving the chemical reactions that produce these molecules.
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	Language		Summary Language		Original Title
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	1083
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	Author	Gerecht, E.; Musante, C.F.; Zhuang, Y.; Ji, M.; Yngvesson, K.S.; Goyette, T.; Waldman, J.
	Title	NbN hot electron bolometric mixer with intrinsic receiver noise temperature of less than five times the quantum noise limit			Type	Conference Article
	Year	2000	Publication	Proc. IMS	Abbreviated Journal
	Volume	2	Issue		Pages	1007-1010
	Keywords	HEB mixer
	Abstract	In recent years, improvements in device development and quasi-optical coupling techniques utilizing planar antennas have led to a significant achievement in low noise receivers for the edges of the submillimeter frequency regime. Hot electron bolometric (HEB) receivers made of thin superconducting films such as NbN have produced a viable option for instruments designed to measure the molecular spectra for astronomical applications as well as in remote sensing of the atmosphere in the THz regime. This paper describes an NbN HEB mixer with intrinsic DSB receiver noise temperature of at most five times the quantum noise limit at frequencies as high as 2.24 THz
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	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	477
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	Author	Finkel, Matvey; Vachtomin, Yuriy; Antipov, Sereey; Drakinski, Vladimir; Kaurova, Natalia; Voronov, Boris; Goltsman, Greeory
	Title	Gain bandwidth and noise temperature of NbTiN HEB mixer			Type	Conference Article
	Year	2003	Publication	Proc. 14^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 14^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	276-285
	Keywords	NbTiN HEB mixer
	Abstract	We have determined that the gain bandwidth of phonon-cooled HEB mixer employing NbTiN films deposited on MgO layer over Si substrate is limited b y the escape of phonons to the substrate. The cut-off frequencies of 1 um long devices operating at T 71, based on 3.5 nm. 4 nm and 10 nm thick films amount to 400 Mk. 300 MHz, and 100 MHz, respectivel y . The gain bandwidth of 0.13 . um long devices fabricated from 3.5 nm thick film is larger and amounts to 0.8 GIL; at the optimal operating point and to 1.5 GIL: at larger bias. The increase of the gain bandwidth from 400 MHz up to 1.5 GH: with the change of bridge length is attributed to diffusion cooling. A double sideband noise temperature of 4000 K was obtained for heterodyne receiver utilizing pilot NbTiN HEB mixer (not optimized for normal state resistance) operating at the local oscillator frequency of 2.5 THz.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
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	Notes				Approved	no
	Call Number				Serial	1500
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	Author	Goltsman, Gregory N.; Vachtomin, Yuriy B.; Antipov, Sergey V.; Finkel, Matvey I.; Maslennikov, Sergey N.; Polyakov, Stanislav L.; Svechnikov, Sergey I.; Kaurova, Natalia S.; Grishina, Elisaveta V.; Voronov, Boris M.
	Title	Low-noise NbN phonon-cooled hot-electron bolometer mixers for terahertz heterodyne receivers			Type	Conference Article
	Year	2005	Publication	Proc. 9-th WMSCI	Abbreviated Journal	Proc. 9-th WMSCI
	Volume	9	Issue		Pages	154-159
	Keywords	NbN HEB mixers
	Abstract
	Address
	Corporate Author				Thesis
	Publisher	International Institute of Informatics and Systemics	Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
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	Notes				Approved	no
	Call Number				Serial	547
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	Author	Maezawa, Hiroyuki
	Title	Application of superconducting hot-electron bolometer mixers for terahertz-band astronomy			Type	Journal Article
	Year	2015	Publication	IEICE Trans. Electronics	Abbreviated Journal
	Volume	98	Issue	3	Pages	196-206
	Keywords	HEB mixer applications, HEB applications
	Abstract	Recently, a next-generation heterodyne mixer detector – a hot electron bolometer (HEB) mixer employing a superconducting microbridge – has gradually opened up terahertz-band astronomy. The surrounding state-of-the-art technologies including fabrication processes, 4 K cryostats, cryogenic low-noise amplifiers, local oscillator sources, micromachining techniques, and spectrometers, as well as the HEB mixers, have played a valuable role in the development of super-low-noise heterodyne spectroscopy systems for the terahertz band. The current developmental status of terahertz-band HEB mixer receivers and their applications for spectroscopy and astronomy with ground-based, airborne, and satellite telescopes are presented.
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	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Notes				Approved	no
	Call Number				Serial	1073
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	Author	Ryabchun, S. A.; Tretyakov, I. V.; Pentin, I. V.; Kaurova, N. S.; Seleznev, V. A.; Voronov, B. M.; Finkel, M. I.; Maslennikov, S. N.; Gol'tsman, G. N.
	Title	Low-noise wide-band hot-electron bolometer mixer based on an NbN film			Type	Journal Article
	Year	2009	Publication	Radiophys. Quant. Electron.	Abbreviated Journal
	Volume	52	Issue	8	Pages	576-582
	Keywords	HEB mixer, in-situ contacts, noise temperature, conversion gain bandwidth, diffusion cooling channel
	Abstract	We develop and study a hot-electron bolometer mixer made of a two-layer NbN–Au film in situ deposited on a silicon substrate. The double-sideband noise temperature of the mixer is 750 K at a frequency of 2.5 THz. The conversion efficiency measurements show that at the superconducting transition temperature, the intermediate-frequency bandwidth amounts to about 6.5 GHz for a mixer 0.112 μm long. These record-breaking characteristics are attributed to the improved contacts between a sensitive element and a helical antenna and are reached due to using the in situ deposition of NbN and Au layers at certain stages of the process.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
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	Notes				Approved	no
	Call Number				Serial	599
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	Author	Рябчун, С. А.; Третьяков, И. В.; Пентин, И. В; Каурова, Н. С.; Селезнев, В. А; Воронов, Б. М.; Финкель, М. И.; Масленников, С. Н.; Гольцман, Г. Н.
	Title	Малошумящий широкополосный терагерцовый смеситель на эффекте электронного разогрева в плёнке NbN			Type	Journal Article
	Year	2009	Publication	Известия высших учебных заведений. Радиофизика	Abbreviated Journal
	Volume	52	Issue	8	Pages	641-648
	Keywords	HEB mixer, in-situ contacts, noise temperature, conversion gain bandwidth, diffusion cooling channel
	Abstract	Разработан и исследован смеситель на горячих электронах, изготовленный из двуслойной плёнки NbN-Au, осаждённой на кремневую подложку in situ. Двухполосная шумовая температура устройства составила 750 К на частоте 2.5 ТГц. Измерения эффективности преобразования для смесителя длиной 0.112 мкм вблизи температуры сверхпроводящего перехода показали полосу промежуточных частот около 6.5 ГГц. Эти результаты являются рекордными и были получены за счёт улучшения контактов между чувствительным элементом и спиральной антенной при замене технологического маршрута с нанесением слоёв NbN и Au в отдельных процессах на технологический процесс, в котором данные слои наносятся in situ без нарушения вакуума.
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	Language		Summary Language		Original Title
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	Notes				Approved	no
	Call Number				Serial	600
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	Author	Barends, R.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.
	Title	Current-induced vortex unbinding in bolometer mixers			Type	Journal Article
	Year	2005	Publication	Applied Physics Letters	Abbreviated Journal	Appl. Phys. Lett.
	Volume	87	Issue		Pages	263506 (1 to 3)
	Keywords	HEB mixer numerical model, HEB model, IV-curves, vortex-antivortex, Berezinskii–Kosterlitz–Thouless theory, diffusion cooling channel, diffusion channel, distributed HEB model, distributed model, self-heating effect, temperature profile
	Abstract	We present a description of the current-voltage characteristics of hot electron bolometers in terms of the current-dependent intrinsic resistive transition of NbN films. We find that, by including this current dependence, we can correctly predict the complete current-voltage characteristics, showing excellent agreement with measurements for both low and high bias and for small as well as large devices. It is assumed that the current dependence is due to vortex-antivortex unbinding as described in the Berezinskii–Kosterlitz–Thouless theory. The presented approach will be useful in guiding device optimization for noise and bandwidth.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Notes				Approved	no
	Call Number				Serial	604
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	Author	Nebosis, R. S.; Semenov, A. D.; Gousev, Yu. P.; Renk, K. F.
	Title	Rigorous analysis of a superconducting hot-electron bolometer mixer: theory and comparision with experiment			Type	Conference Article
	Year	1996	Publication	Proc. 7^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal
	Volume		Issue		Pages	601-613
	Keywords	HEB mixer, model, conversion gain, noise temperature, impedance, 2.5 THz
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Charlottesville, Virginia, USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	605
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	Author	Risacher, C.; Meledin, D.; Belitsky, V.; Bergman, P.
	Title	First 1.3 THz observations at the APEX telescope			Type	Conference Article
	Year	2009	Publication	Proc. 20^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal
	Volume		Issue		Pages	54-61
	Keywords	balanced HEB mixer noise temperature APEX telescope stability Allan variance aperture efficiency
	Abstract	The Atacama Pathfinder EXperiment (APEX) 12m telescope is operating on the Llano Chajnantor, Chile, since 2003 and a set of state of the art sub-millimeter receivers have been installed for frequencies spanning from 150 GHz to 1500 GHz. In 2008, a balanced 1.3 THz Hot Electron Bolometer (HEB) receiver was installed for the atmospheric window 1250-1380 GHz. This instrument is part of a 4-channel receiver cryostat with the other channels being 211-275 GHz, 275-370 GHz and 380-500 GHz Sideband Separating (SSB) SIS receivers. This paper presents the first observations obtained so far with the 1.3 THz band during its first months of operation. The sky measurements were taken during opportunistic commissioning and science verification phases, when the weather conditions were sufficiently good with a Precipitable Water Vapor (PWV) below 0.25 mm, which was the case only a few nights during these months. We present the first observations of the molecular transition CO J=(11-10) line on different sources such as Orion-FIR4, CW-Leo and SgrB2(M). We describe the many challenges and difficulties encountered for achieving successful THz observations from a large sub-millimeter ground-based telescope.
	Address
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	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	619
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	Author	Zhang, W.; Khosropanah, P.; Gao, J. R.; Kollberg, E. L.; Yngvesson, K. S.; Bansal, T.; Barends, R.; Klapwijk, T. M.
	Title	Quantum noise in a terahertz hot electron bolometer mixer			Type	Journal Article
	Year	2010	Publication	Applied Physics Letters	Abbreviated Journal	Appl. Phys. Lett.
	Volume	96	Issue	11	Pages	111113-(1-3)
	Keywords	HEB mixer, quantum limit, quantum noise, vacuum box, THz, Terahertz
	Abstract	We have measured the noise temperature of a single, sensitive superconducting NbN hot electron bolometer (HEB) mixer in a frequency range from 1.6 to 5.3 THz, using a setup with all the key components in vacuum. By analyzing the measured receiver noise temperature using a quantum noise (QN) model for HEB mixers, we confirm the effect of QN. The QN is found to be responsible for about half of the receiver noise at the highest frequency in our measurements. The beta-factor (the quantum efficiency of the HEB) obtained experimentally agrees reasonably well with the calculated value.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	624
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	Author	Huebers, Heinz-Wilhelm; Pavlov, S.; Semenov, A.; Köhler, R.; Mahler, L.; Tredicucci, A.; Beere, H.; Ritchie, D.; Linfield, E.
	Title	Terahertz quantum cascade laser as local oscillator in a heterodyne receiver			Type	Journal Article
	Year	2005	Publication	Optics Express	Abbreviated Journal
	Volume	13	Issue	15	Pages	5890-5896
	Keywords	QCL heterodyne, 6 mW at 2.5 THz, HEB mixer, terahertz
	Abstract	Terahertz quantum cascade lasers have been investigated with respect to their performance as a local oscillator in a heterodyne receiver. The beam profile has been measured and transformed in to a close to Gaussian profile resulting in a good matching between the field patterns of the quantum cascade laser and the antenna of a superconducting hot electron bolometric mixer. Noise temperature measurements with the hot electron bolometer and a 2.5 THz quantum cascade laser yielded the same result as with a gas laser as local oscillator.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	627
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	Author	Rabanus, D.; Graf, U. U.; Philipp, M.; Ricken, O.; Stutzki, J.; Vowinkel, B.; Wiedner, M. C.; Walther, C.; Fischer, M.; Faist, J.
	Title	Phase locking of a 1.5 terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver			Type	Journal Article
	Year	2009	Publication	Optics Express	Abbreviated Journal
	Volume	17	Issue	3	Pages	1159-1168
	Keywords	QCL heterodyne, 300 uW at 1.5 THz, HEB mixer
	Abstract	We demonstrate for the first time the closure of an electronic phase lock loop for a continuous–wave quantum cascade laser (QCL) at 1.5 THz. The QCL is operated in a closed cycle cryo cooler. We achieved a frequency stability of better than 100 Hz, limited by the resolution bandwidth of the spectrum analyser. The PLL electronics make use of the intermediate frequency (IF) obtained from a hot electron bolometer (HEB) which is downconverted to a PLL IF of 125 MHz. The coarse selection of the longitudinal mode and the fine tuning is achieved via the bias voltage of the QCL. Within a QCL cavity mode, the free-running QCL shows frequency fluctuations of about 5 MHz, which the PLL circuit is able to control via the Stark–shift of the QCL gain material. Temperature dependent tuning is shown to be nonlinear, and of the order of -16 MHz/K. Additionally we have used the QCL as local oscillator (LO) to pump an HEB and perform, again for the first time at 1.5 THz, a heterodyne experiment, and obtain a receiver noise temperature of 1741 K.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	628
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	Author	Ryabchun, Sergey; Tong, Cheuk-Yu Edward; Paine, Scott; Lobanov, Yury; Blundell, Raymond; Goltsman, Gregory
	Title	Temperature resolution of an HEB receiver at 810 GHz			Type	Journal Article
	Year	2009	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal	IEEE Trans. Appl. Supercond.
	Volume	19	Issue	3	Pages	293-296
	Keywords	HEB mixer
	Abstract	We present the results of direct measurements of the temperature resolution of an HEB receiver operating at 810 GHz, in both continuum and spectroscopic modes. In the continuum mode, the input of the receiver was switched between black bodies with different physical temperatures. With a system noise temperature of around 1100 K, the receiver was able to resolve loads which differed in temperature by about 1 K over an integration time of 5 seconds. This resolution is significantly worse than the value of 0.07 K given by the radiometer equation. In the spectroscopic mode, a gas cell filled with carbonyl sulphide (OCS) gas was used and the emission line at 813.3537060 GHz was measured using the receiver in conjunction with a digital spectrometer. From the observed spectra, we determined that the measurement uncertainty of the equivalent emission temperature was 2.8 K for an integration time of 0.25 seconds and a spectral resolution of 12 MHz, compared to a 1.4 K temperature resolution given by the radiometer equation. This relative improvement is due to the fact that at short integration times the contribution from 1/f noise and drift are less dominant. In both modes, the temperature resolution was improved by about 40% with the use of a feedback loop which adjusted the level of an injected microwave radiation to maintain a constant operating current of the HEB mixer. This stabilization scheme has proved to be very effective to keep the temperature resolution of the HEB receiver to close to the theoretical value given by the radiometer equation.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	636
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	Author	Tretyakov, Ivan; Ryabchun, Sergey; Finkel, Matvey; Maslennikova, Anna; Kaurova, Natalia; Lobastova, Anastasia; Voronov, Boris; Gol'tsman, Gregory
	Title	Low noise and wide bandwidth of NbN hot-electron bolometer mixers			Type	Journal Article
	Year	2011	Publication	Appl. Phys. Lett.	Abbreviated Journal	Appl. Phys. Lett.
	Volume	98	Issue		Pages	033507 (1 to 3)
	Keywords	NbN HEB mixer
	Abstract	We report a record double sideband noise temperature of 600 K (5hÎ½/kB) offered by a NbN hot-electron bolometer receiver at 2.5 THz. Allowing for standing wave effects, this value was found to be constant in the intermediate frequency range 1–7 GHz, which indicates that the mixer has an unprecedentedly large noise bandwidth in excess of 7 GHz. The insight into this is provided by gain bandwidth measurements performed at the superconducting transition. They show that the dependence of the bandwidth on the mixer length follows the model for an HEB mixer with diffusion and phonon cooling of the hot electrons.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	638
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	Author	Масленникова, А. В.; Рябчун, С. А.; Финкель, М. И.; Каурова, Н. С.; Исупова, А. А.; Воронов, Б. М.; Гольцман, Г. Н.
	Title	Широкополосные смесители на горячих электронах на основе NbN наноструктур			Type	Journal Article
	Year	2011	Publication	Труды Московского физико-технического института	Abbreviated Journal	Труды МФТИ
	Volume	3	Issue	2	Pages	31-34
	Keywords	HEB mixer
	Abstract	Мы приводим данные исследования полосы преобразования смесителей на горячих электронах (hot-electron bolometer, НЕВ), изготовленных на основе тонких пленок NbN. Зависимость полосы преобразования от длины смесительного элемента находится в прекрасном согласии с результатами теоретической модели HEB-смесителя, в котором энергетическая релаксация электронов одновременно происходит по двум каналам: фононному и диффузионному.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
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	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	646
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	Author	de Lange, Gert; Krieg, Jean-Michel; Honingh, Netty; Karpov, Alexandre; Cherednichenko, Sergey
	Title	Performance of the HIFI flight mixers			Type	Conference Article
	Year	2008	Publication	Proc. 19^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal
	Volume		Issue		Pages	98-105
	Keywords	HEB mixer applications, HEB applications
	Abstract	We summarize the technology and final results of the superconducting heterodyne SIS and HEB mixers that are developed for the HIFI instrument. Within HIFI 7 frequency bands cover the frequency range from 480 GHz to 1910 GHz. We describe the different device technologies and optical coupling schemes that are used to cover the frequency bands. The efforts of the different mixer teams that participate in HIFI have contributed to an instrument that will have unprecedented sensitivity and frequency coverage.
	Address	Groningen
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	1074
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	Author	Tretyakov, Ivan; Ryabchun, Sergey; Finkel, Matvey; Maslennikov, Sergey; Maslennikova, Anna; Kaurova, Natalia; Lobastova, Anastasia; Voronov, Boris; Gol'tsman, Gregory
	Title	Ultrawide noise bandwidth of NbN hot-electron bolometer mixers with in situ gold contacts			Type	Journal Article
	Year	2011	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal
	Volume	21	Issue	3	Pages	620-623
	Keywords	NbN HEB mixer bandwidth
	Abstract	We report a noise bandwidth of 7 GHz in the new generation of NbN hot-electron bolometer (HEB) mixers that are being developed for the space observatory Millimetron. The HEB receiver driven by a 2.5-THz local oscillator offered a noise temperature of 600 K in a 50-MHz final detection bandwidth. As the filter center frequency was swept this value remained nearly constant up to the cutoff frequency of the cryogenic amplifier at 7 GHz. We believe that such a low value of the noise temperature is due to reduced radio frequency (RF) loss at the interface between the superconducting film and the gold contacts. We have also performed gain bandwidth measurements at the superconducting transition on HEB mixers with various lengths and found them to be in excellent agreement with the results of the analytical and numerical models developed for the HEB mixer with both diffusion and phonon cooling of hot electrons.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	716
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	Author	Lobanov, Y.; Tong, E.; Blundell, R.; Hedden, A.; Voronov, B.; Gol'tsman, G.
	Title	Large-signal frequency response of an HEB mixer: from 300 MHz to terahertz			Type	Journal Article
	Year	2011	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal
	Volume	21	Issue	3	Pages	628-631
	Keywords	waveguide NbN HEB mixers
	Abstract	We present a study of the large signal frequency response of an HEB mixer over a wide frequency range. In our experiments, we have subjected the HEB mixer to incident electromagnetic radiation from 0.3 GHz to 1 THz. The mixer element is an NbN film deposited on crystalline quartz. The mixer chip is mounted in a waveguide cavity, coupled to free space with a diagonal horn. At microwave frequencies, electromagnetic radiation is applied through the coaxial bias port of the mixer block. At higher frequencies the input signal passes via the diagonal horn feed. At each frequency, the incident power is varied and a family of I-V curves is recorded. From the curves we identify 3 distinct regimes of operation of the mixer separated by the phonon relaxation frequency and the superconducting energy gap frequency observed at about 3 GHz and 660 GHz respectively. In this paper, we will present observed curves and discuss the results of our experiment.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	719
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	Author	Lobanov, Y.V.; Tong, C.-Y.E.; Hedden, A.S.; Blundell, R.; Voronov, B.M.; Gol'tsman, G.N.
	Title	Direct measurement of the gain and noise bandwidths of HEB mixers			Type	Journal Article
	Year	2011	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal	IEEE Trans. Appl. Supercond.
	Volume	21	Issue	3	Pages	645-648
	Keywords	waveguide NbN HEB mixers
	Abstract	The intermediate frequency (IF) bandwidth of a hot electron bolometer (HEB) mixer is an important parameter of the mixer, in that it helps to determine its suitability for a given application. With the availability of wideband low noise amplifiers, it is simple to measure the performance of an HEB mixer over a wide range of IF at a fixed LO frequency using the standard Y-factor method. This in-situ method allows us to measure both the gain and noise bandwidths simultaneously. We have also measured mixer output impedance with a vector network analyser. Intrinsic time constant has been extracted from the impedance data and compared to the mixer's bandwidths determined from receiver Y-factor measurement.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
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	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	720
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	Author	Lobanov, Y.; Tong, C.; Blundell, R.; Gol'tsman, G.
	Title	A study of direct detection effect on the linearity of hot electron bolometer mixers			Type	Conference Article
	Year	2009	Publication	Proc. 20^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 20th ISSTT
	Volume		Issue		Pages	282-287
	Keywords	HEB mixer, direct detection effect
	Abstract	We have performed a study of how direct detection affects the linearity and hence the calibration of an HEB mixer. Two types of waveguide HEB devices have been used: a 0.8 THz HEB mixer and a 1.0 THz HEB mixer which is ~5 times smaller than the former. Two independent experimental approaches were used. In the Î”G/G method, the conversion gain of the HEB mixer is first measured as a function of the bias current for a number of bias voltages. At each bias setting, we carefully measure the change in the operating current when the input loads are switched. From the measured data, we can derive the expected difference in gain between the hot and cold loads. In the second method (injection method [1]), the linearity of the HEB mixer is independently measured by injecting a modulated signal for different input load temperatures. The results of both approaches confirm that there is gain compression in the operation of HEB mixers. Based on the results of our measurements, we discuss the impact of direct detection effects on the operation of HEB mixers.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	724
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	Author	Lobanov, Y. V.; Tong, Cheuk-Yu E.; Hedden, A. S.; Blundell, R.; Gol'tsman, G. N.
	Title	Microwave-assisted슠measurement슠of the슠frequency슠response슠of슠terahertz슠HEB슠mixers슠with a슠fourier슠transform슠spectrometer			Type	Conference Article
	Year	2010	Publication	21st International Symposium on Space Terahertz Technology	Abbreviated Journal	21st ISSTT
	Volume		Issue		Pages	420-423
	Keywords	HEB mixer
	Abstract	We describe a novel method of operation of the HEB direct detector for use with a Fourier Transform Spectrometer. Instead of elevating the bath temperature, we have measured the RF response of waveguide HEB mixers by applying microwave radiation to select appropriate bias conditions. In our experiment, a microwave signal is injected into the HEB mixer via its IF port. By choosing an appropriate injection level, the device can be operated close to the desired operating point. Furthermore, we have shown that both thermal biasing and microwave injection can reproduce the same spectral response of the HEB mixer. However, with the use of microwave injection, there is no need to wait for the mixer to reach thermal equilibrium, so characterisation can be done in less time. Also, the liquid helium consumption for our wet cryostat is also reduced. We have demonstrated that the signalto-noise ratio of the FTS measurements can be improved with microwave injection.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	725
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	Author	Burke, P. J.; Schoelkopf, R. J.; Prober, D. E.; Skalare, A.; Karasik, B. S.; Gaidis, M. C.; McGrath, W. R.; Bumble, B.; Leduc, H. G.
	Title	Spectrum of thermal fluctuation noise in diffusion and phonon cooled hot-electron mixers			Type	Journal Article
	Year	1998	Publication	Applied Physics Letters	Abbreviated Journal	Appl. Phys. Lett.
	Volume	72	Issue	12	Pages	1516-1518
	Keywords	HEB mixer; thermal fluctuation noise; TFN
	Abstract	A systematic study of the intermediate frequency noise bandwidth of Nb thin-film superconducting hot-electron bolometers is presented. We have measured the spectrum of the output noise as well as the conversion efficiency over a very broad intermediate frequency range (from 0.1 to 7.5 GHz) for devices varying in length from 0.08 μm to 3 μm. Local oscillator and rf signals from 8 to 40 GHz were used. For a device of a given length, the spectrum of the output noise and the conversion efficiency behave similarly for intermediate frequencies less than the gain bandwidth, in accordance with a simple thermal model for both the mixing and thermal fluctuation noise. For higher intermediate frequencies the conversion efficiency decreases; in contrast, the noise decreases but has a second contribution which dominates at higher frequency. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, between 120 and 530 K (double side band).
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	RPLAB @ gujma @			Serial	760
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	Author	Shurakov, Alexander; Tong, Edward; Blundell, Raymond; Gol'tsman, Gregory
	Title	Microwave stabilization of HEB mixer by a microchip controller			Type	Conference Article
	Year	2012	Publication	IEEE MTT-S international microwave symposium digest	Abbreviated Journal
	Volume		Issue		Pages	1-3
	Keywords	HEB mixer stability, microwave injection, Allan variance, Allan time
	Abstract	The stability of a Hot Electron Bolometer (HEB) mixer can be improved by the use of microwave injection. In this article we report a refinement of this approach. We introduce a microchip controller to facilitate the implementation of the stabilization scheme, and demonstrate that the feedback loop effectively suppresses drifts in the HEB bias current, leading to an improvement in the receiver stability. The measured Allan time of the mixer's IF output power is increased to > 10 s.
	Address	Montreal, QC, Canada
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
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	Notes				Approved	no
	Call Number				Serial	857
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	Author	Khosropanah, P.; Merkel, H.; Yngvesson, S.; Adam, A.; Cherednichenko, S.; Kollberg, E.
	Title	A distributed device model for phonon-cooled HEB mixers predicting IV characteristics, gain, noise and IF bandwidth			Type	Conference Article
	Year	2000	Publication	Proc. 11^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal
	Volume		Issue		Pages	474-488
	Keywords	HEB mixer numerical model, diffusion cooling channel, diffusion channel, distributed HEB model, distributed model
	Abstract	A distributed model for phonon-cooled superconductor hot electron bolometer (HEB) mixers is given, which is based on solving the one-dimensional heat balance equation for the electron temperature profile along the superconductor strip. In this model it is assumed that the LO power is absorbed uniformly along the bridge but the DC power absorption depends on the local resistivity and is thus not uniform. The electron temperature dependence of the resistivity is assumed to be continuous and has a Fermi form. These assumptions are used in setting up the non-linear heat balance equation, which is solved numerically for the electron temperature profile along the bolometer strip. Based on this profile the resistance of the device and the IV curves are calculated. The IV curves are in excellent agreement with measurement results. Using a small signal model the conversion gain of the mixer is obtained. The expressions for Johnson noise and thermal fluctuation noise are derived. The calculated results are in close agreement with measurements, provided that one of the parameters used is adjusted.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	University of Michigan, Ann Arbor, MI USA	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	893
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	Author	Ynvesson, K. Sigfrid; Kollberg, Erik L.
	Title	Optimum receiver noise temperature for NbN HEB mixers according to standard model			Type	Conference Article
	Year	1999	Publication	Proc. 10^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal
	Volume		Issue		Pages	566-582
	Keywords	HEB mixer model, standard model, electro-thermal feedback, self-heating parameter, heating efficiency
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	895
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	Author	Pütz, P.; Honingh, C. E.; Jacobs, K.; Justen, M.; Schultz, M.; Stutzki, J.
	Title	Terahertz hot electron bolometer waveguide mixers for GREAT			Type	Journal Article
	Year	2012	Publication	Astron. Astrophys.	Abbreviated Journal	A&A
	Volume	542	Issue		Pages	L2
	Keywords	HEB mixer, applications
	Abstract	Context. Supplementing the publications based on the first-light observations with the German REceiver for Astronomy at Terahertz frequencies (GREAT) on SOFIA, we present background information on the underlying heterodyne detector technology. This Letter complements the GREAT instrument Letter and focuses on the mixers itself. Aims. We describe the superconducting hot electron bolometer (HEB) detectors that are used as frequency mixers in the L1 (1400 GHz), L2 (1900 GHz), and M (2500 GHz) channels of GREAT. Measured performance of the detectors is presented and background information on their operation in GREAT is given. Methods. Our mixer units are waveguide-based and couple to free-space radiation via a feedhorn antenna. The HEB mixers are designed, fabricated, characterized, and flight-qualified in-house. We are able to use the full intermediate frequency bandwidth of the mixers using silicon-germanium multi-octave cryogenic low-noise amplifiers with very low input return loss. Results. Superconducting HEB mixers have proven to be practical and sensitive detectors for high-resolution THz frequency spectroscopy on SOFIA. We show that our niobium-titanium-nitride (NbTiN) material HEBs on silicon nitride (SiN) membrane substrates have an intermediate frequency (IF) noise roll-off frequency above 2.8 GHz, which does not limit the current receiver IF bandwidth. Our mixer technology development efforts culminate in the first successful operation of a waveguide-based HEB mixer at 2.5 THz and deployment for radioastronomy. A significant contribution to the success of GREAT is made by technological development, thorough characterization and performance optimization of the mixer and its IF interface for receiver operation on SOFIA. In particular, the development of an optimized mixer IF interface contributes to the low passband ripple and excellent stability, which GREAT demonstrated during its initial successful astronomical observation runs.
	Address
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	Notes				Approved	no
	Call Number				Serial	907
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	Author	Cherednichenko, Sergey; Drakinskiy, Vladimir; Berg, Therese; Khosropanah, Pourya; Kollberg, Erik
	Title	Hot-electron bolometer terahertz mixers for the Herschel Space Observatory			Type	Journal Article
	Year	2008	Publication	Review of Scientific Instruments	Abbreviated Journal	Rev. Sci. Instrum.
	Volume	79	Issue		Pages	034501
	Keywords	HEB mixer, HEB detector, HEB direct detector, applications
	Abstract	We report on low noise terahertz mixers(1.4–1.9THz) developed for the heterodyne spectrometer onboard the Herschel Space Observatory. The mixers employ double slot antenna integrated superconducting hot-electron bolometers (HEBs) made of thin NbN films. The mixer performance was characterized in terms of detection sensitivity across the entire rf band by using a Fourier transform spectrometer (from 0.5to2.5THz, with 30GHz resolution) and also by measuring the mixernoise temperature at a limited number of discrete frequencies. The lowest mixernoise temperature recorded was 750K [double sideband (DSB)] at 1.6THz and 950KDSB at 1.9THz local oscillator (LO) frequencies. Averaged across the intermediate frequency band of 2.4–4.8GHz, the mixernoise temperature was 1100KDSB at 1.6THz and 1450KDSB at 1.9THz LO frequencies. The HEB heterodyne receiver stability has been analyzed and compared to the HEB stability in the direct detection mode. The optimal local oscillator power was determined and found to be in a 200–500nW range.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	908
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	Author	Khosropanah, Pourya
	Title	NbN and NbTiN hot electron bolometer THz mixers			Type	Book Whole
	Year	2003	Publication	Chalmers University of Technology	Abbreviated Journal
	Volume		Issue		Pages
	Keywords	HEB mixer, hot electron bolometer mixer, NbN, NbTiN, superconducting detector, heterodyne receiver, THz mixer, submillimeter mixer, quasioptical receiver, double slot antenna, twin slot antenna, spiral antenna, receiver noise, FTS, Fourier Transform Spectrometer
	Abstract	The thesis reports the development of Hot Electron Bolometer (HEB) mixers for radio astronomy heterodyne receivers in THz frequency range. Part of this work is the fabrication of HEB devices, which are based on NbN or NbTiN superconducting thin films (â‰<a4>5 nm). They are integrated with wideband spiral or double-slot planar antennas. The mixer chips are incorporated into a quasi-optical receiver. The experimental part of this work focuses on the characterization of the receiver as a whole, and the HEB mixers as a part. Double side band receiver noise temperature and the IF bandwidth are reported for frequencies from 0.7 THz up to 2.6 THz. The spectrum of the direct response of HEB integrated with dierent antennas are measured using Fourier Transform Spectrometer (FTS). The effect of the bolometer size on total receiver performance and the LO power requirements is also discussed. A high-yield and reliable process for fabrication of NbN HEB mixers have been achieved. Over 100 devices with different bolometer geometry, film property and also different antennas have been fabricated and measured. The measured data enables us to discuss the impact of different parameters to the receiver overall performance. This work has provided NbN HEB mixers to the following receivers: TREND (Terahertz REceiver with NbN HEB Device) operating at 1.25-1.5 THz, installed in AST/RO Submillimeter Wave Telescope, Amundsen/Scott South Pole Station, in 2002-2003. Band 6-low (1.410-1.700 THz) and 6-high (1.700-1.920 THz) of the HIFI (Heterodyne Instrument for Far Infra-red) in the Herschel Space Observatory, due to launch in 2007 by ESA (European Space Agency). Besides, there has been continuous efforts to develop better models to explain the mixer performance more accurately. They are based on two temperature model for electrons and phonons and solving one-dimensional heat balance equations along the bolometer. The principles of these models are illustrated and the calculated results are compared with measured data.
	Address
	Corporate Author				Thesis	Ph.D. thesis
	Publisher	Chalmers University of Technology	Place of Publication	Göteborg	Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
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	Notes				Approved	no
	Call Number				Serial	910
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	Author	Yagoubov, P.; Kroug, M.; Merkel, H.; Kollberg, E.; Gol'tsman, G.; Svechnikov, S.; Gershenzon, E.
	Title	Noise temperature and local oscillator power requirement of NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies			Type	Journal Article
	Year	1998	Publication	Appl. Phys. Lett.	Abbreviated Journal	Appl. Phys. Lett.
	Volume	73	Issue	19	Pages	2814-2816
	Keywords	NbN HEB mixers, noise temperature, local oscillator power
	Abstract	In this letter, the noise performance of NbN-based phonon-cooled hot electron bolometric quasioptical mixers is investigated in the 0.55–1.1 THz frequency range. The best results of the double-sideband <cd><2018>DSB<cd><2019> noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz, and 1250 K at 1.1 THz. The water vapor in the signal path causes significant contribution to the measured receiver noise temperature around 1.1 THz. The devices are made from 3-nm-thick NbN film on high-resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are typically 0.2Ï«2 um. The amount of local oscillator power absorbed in the bolometer is less than 100 nW.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
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	Notes				Approved	no
	Call Number				Serial	911
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	Author	Klapwijk, T. M.; Barends, R.; Gao, J. R.; Hajenius, M.; Baselmans, J. J. A.
	Title	Improved superconducting hot-electron bolometer devices for the THz range			Type	Conference Article
	Year	2004	Publication	Proc. SPIE	Abbreviated Journal	Proc. SPIE
	Volume	5498	Issue		Pages	129-139
	Keywords	HEB mixer distributed model, numerical model
	Abstract	Improved and reproducible heterodyne mixing (noise temperatures of 950 K at 2.5 THz) has been realized with NbN based hot-electron superconducting devices with low contact resistances. A distributed temperature numerical model of the NbN bridge, based on a local electron and a phonon temperature, has been used to understand the physical conditions during the mixing process. We find that the mixing is predominantly due to the exponential rise of the local resistivity as a function of electron temperature.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
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	Notes	Invited talk, Recommended by Klapwijk			Approved	no
	Call Number				Serial	912
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	Author	Phillips, T. G.; Jefferts, K. B.
	Title	A low temperature bolometer heterodyne receiver for Millimeter wave astronomy			Type	Journal Article
	Year	1973	Publication	Rev. Sci. Instrum.	Abbreviated Journal	Rev. Sci. Instrum.
	Volume	44	Issue	8	Pages	1009-1014
	Keywords	InSb HEB mixer
	Abstract	Liquid helium cooled InSb hot electronbolometers are used in a balanced mixer configuration as detectors for an imagelessmicrowave receiver. The system is designed for mounting at the prime focus of the National Radio Astronomy Observatory (NRAO) 11 m antenna at Kitt Peak, Arizona, and is suitable for the study of rotational line spectra of interstellar gas molecules. Currently the operating frequency is in the 90–140 GHz band where the double sideband system noise temperature is 250 K.
	Address
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	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
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	Notes	Recommended by Klapwijk			Approved	no
	Call Number				Serial	927
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	Author	Miao, W.; Zhang, W.; Zhong, J. Q.; Shi, S. C.; Delorme, Y.; Lefevre, R.; Feret, A; Vacelet, T
	Title	Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges			Type	Journal Article
	Year	2014	Publication	Appl. Phys. Lett.	Abbreviated Journal	<ef><bf><bc>Appl. Phys. Lett.
	Volume	104	Issue		Pages	052605(1-4)
	Keywords	NbN HEB mixers, local oscillator power, RF nonuniform absorption
	Abstract	We interpret the experimental observation of a frequency-dependence of superconducting hot electron bolometer (HEB) mixers by taking into account the non-uniform absorption of the terahertz radiation on the superconducting HEB microbridge. The radiation absorption is assumed to be proportional to the local surface resistance of the HEB microbridge, which is computed using the Mattis-Bardeen theory. With this assumption the dc and mixing characteristics of a superconducting niobium-nitride (NbN) HEB device have been modeled at frequencies below and above the equilibrium gap frequency of the NbN film.
	Address
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	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
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	Notes				Approved	no
	Call Number				Serial	935
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	Author	Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Golts'man, G.; Gershenzon, E.; Voronov B.
	Title	Superconductive NbN hot-electron bolometric mixer performance at 250 GHz			Type	Conference Article
	Year	1996	Publication	Proc. 7^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 7^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	331-336
	Keywords	NbN HEB mixers
	Abstract	Thin film NbN (<40 A) strips are used as waveguide mixer elements. The electron cooling mechanism for the geometry is the electron-phonon interaction. We report a receiver noise temperature of 750 K at 244 GHz, with / IF = 1.5 GHz, Af= 500 MHz, and Tphysical = 4 K. The instantaneous bandwidth for this mixer is 1.6 GHz. The local oscillator (LO) power is 0.5 1.tW with 3 dB-uncertainty. The mixer is linear to 1 dB up to an input power level 6 dB below the LO power. We report the first detection of a molecular line emission using this class of mixer, and that the receiver noise temperature determined from Y-factor measurements reflects the true heterodyne sensitivity.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	945
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	Author	Lobanov, Y.; Shcherbatenko, M.; Finkel, M.; Maslennikov, S.; Semenov, A.; Voronov, B. M.; Rodin, A. V.; Klapwijk, T. M.; Gol'tsman, G. N.
	Title	NbN hot-electron-bolometer mixer for operation in the near-IR frequency range			Type	Journal Article
	Year	2015	Publication	IEEE Trans. Appl. Supercond.	Abbreviated Journal	IEEE Trans. Appl. Supercond.
	Volume	25	Issue	3	Pages	2300704 (1 to 4)
	Keywords	HEB mixer, IR, optical antenna
	Abstract	Traditionally, hot-electron-bolometer (HEB) mixers are employed for THz and “super-THz” heterodyne detection. To explore the near-IR spectral range, we propose a fiber-coupled NbN film based HEB mixer. To enhance the incident-light absorption, a quasi-antenna consisting of a set of parallel stripes of gold is used. To study the antenna effect on the mixer performance, we have experimentally studied a set of devices with different size of the Au stripe and spacing between the neighboring stripes. With use of the well-known isotherm technique we have estimated the absorption efficiency of the mixer, and the maximum efficiency has been observed for devices with the smallest pitch of the alternating NbN and NbN-Au stripes. Also, a proper alignment of the incident Eâƒ<2014>-field with respect to the stripes allows us to improve the coupling further. Studying IV-characteristics of the mixer under differently-aligned Eâƒ<2014>-field of the incident radiation, we have noticed a difference in their shape. This observation suggests that a difference exists in the way the two waves with orthogonal polarizations parallel and perpendicular Eâƒ<2014>-field to the stripes heat the electrons in the HEB mixer. The latter results in a variation in the electron temperature distribution over the HEB device irradiated by the two waves.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	952
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	Author	Maslennikov, S.
	Title	RF heating efficiency of the terahertz superconducting hot-electron bolometer			Type	Journal Article
	Year	2014	Publication	arXiv	Abbreviated Journal	arXiv
	Volume	1404.5276	Issue		Pages	1-4
	Keywords	superconducting hot-electron bolometer mixer, HEB, NbN, distributed model, HEB model, HEB mixer model, heat balance equa-tions, conversion gain, RF heating efficiency, noise temperature, simulation, Euler method
	Abstract	We report results of the numerical solution by the Euler method of the system of heat balance equations written in recurrent form for the superconducting hot-electron bolometer (HEB) embedded in an electrical circuit. By taking into account the dependence of the HEB resistance on the transport current we have been able to calculate rigorously the RF heating efficiency, absorbed local oscillator (LO) power and conversion gain of the HEB mixer. We show that the calculated conversion gai nis in excellent agreement with the experimental results, and that the substitution of the calculated RF heating efficiency and absorbed LO power into the expressions for the conversion gain and noise temperature given by the analytical small-signal model of the HEB yields excellent agreement with the corresponding measured values
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	Notes				Approved	no
	Call Number	RPLAB @ atomics90 @			Serial	954
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	Author	Cherednichenko, S.; Yagoubov, P.; Il'in, K.; Gol'tsman, G.; Gershenzon, E.
	Title	Large bandwidth of NbN phonon-cooled hot-electron bolometer mixers			Type	Conference Article
	Year	1997	Publication	Proc. 27th Eur. Microwave Conf.	Abbreviated Journal
	Volume	2	Issue		Pages	972-977
	Keywords	HEB mixer, fabrication process
	Abstract	The bandwidth of NbN phonon-cooled hot electron bolometer mixers has been systematically investigated with respect to the film thickness and film quality variation. The films, 2.5 to 10 nm thick, were fabricated on sapphire substrates using DC reactive magnetron sputtering. All devices consisted of several parallel strips, each 1 um wide and 2 um long, placed between Ti-Au contact pads. To measure the gain bandwidth we used two identical BWOs operating in the 120-140 GHz frequency range, one functioning as a local oscillator and the other as a signal source. The majority of the measurements were made at an ambient temperature of 4.2 K with optimal LO and DC bias. The maximum 3 dB bandwidth (about 4 GHz) was achieved for the devices made of films which were 2.5-3.5 nm thick, had a high critical temperature, and high critical current density. A theoretical analysis of bandwidth for these mixers based on the two-temperature model gives a good description of the experimental results if one assumes that the electron temperature is equal to the critical temperature.
	Address	Jerusalem, Israel
	Corporate Author				Thesis
	Publisher	IEEE	Place of Publication		Editor
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	Area		Expedition		Conference	27th Eur. Microwave Conf.
	Notes				Approved	no
	Call Number				Serial	1075
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	Author	Benz, A. O.; Bruderer, S.; van Dishoeck, E. F.; Stäuber, P.; Wampfler, S. F.; Melchior, M.; Dedes, C.; Wyrowski, F.; Doty, S. D.; van der Tak, F.; Bächtold, W.; Csillaghy, A.; Megej, A.; Monstein, C.; Soldati, M.; Bachiller, R.; Baudry, A.; Benedettini, M.; Bergin, E.; Bjerkeli, P.; Blake, G. A.; Bontemps, S.; Braine, J.; Caselli, P.; Cernicharo, J.; Codella, C.; Daniel, F.; di Giorgio, A. M.; Dieleman, P.; Dominik, C.; Encrenaz, P.; Fich, M.; Fuente, A.; Giannini, T.; Goicoechea, J. R.; de Graauw, Th.; Helmich, F.; Herczeg, G. J.; Herpin, F.; Hogerheijde, M. R.; Jacq, T.; Jellema, W.; Johnstone, D.; Jørgensen, J. K.; Kristensen, L. E.; Larsson, B.; Lis, D.; Liseau, R.; Marseille, M.; McCoey, C.; Melnick, G.; Neufeld, D.; Nisini, B.; Olberg, M.; Ossenkopf, V.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago-García, J.; Saraceno, P.; Schieder, R.; Shipman, R.; Stutzki, J.; Tafalla, M.; Tielens, A. G. G. M.; van Kempen, T. A.; Visser, R.; Yıldız, U. A.
	Title	Hydrides in young stellar objects: Radiation tracers in a protostar-disk-outflow system			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L35 (1 to 5)
	Keywords	HEB mixer applications, HIFI, Herschel
	Abstract	Context. Hydrides of the most abundant heavier elements are fundamental molecules in cosmic chemistry. Some of them trace gas irradiated by UV or X-rays. Aims. We explore the abundances of major hydrides in W3 IRS5, a prototypical region of high-mass star formation. Methods. W3 IRS5 was observed by HIFI on the Herschel Space Observatory with deep integration (2500 s) in 8 spectral regions. Results. The target lines including CH, NH, H3O+, and the new molecules SH+, H2O+, and OH+ are detected. The H2O+ and OH+ J = 1–0 lines are found mostly in absorption, but also appear to exhibit weak emission (P-Cyg-like). Emission requires high density, thus originates most likely near the protostar. This is corroborated by the absence of line shifts relative to the young stellar object (YSO). In addition, H2O+ and OH+ also contain strong absorption components at a velocity shifted relative to W3 IRS5, which are attributed to foreground clouds. Conclusions. The molecular column densities derived from observations correlate well with the predictions of a model that assumes the main emission region is in outflow walls, heated and irradiated by protostellar UV radiation.
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	Notes				Approved	no
	Call Number				Serial	1082
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	Author	Bujarrabal, V.; Alcolea, J.; Soria-Ruiz, R.; Planesas, P.; Teyssier, D.; Marston, A. P.; Cernicharo, J.; Decin, L.; Dominik, C.; Justtanont, K.; de Koter, A.; Melnick, G.; Menten, K. M.; Neufeld, D. A.; Olofsson, H.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.; Quintana-Lacaci, G.; Güsten, R.; Gallego, J. D.; Díez-González, M. C.; Barcia, A.; López-Fernández, I.; Wildeman, K.; Tielens, A. G. G. M.; Jacobs, K.
	Title	Herschel/HIFI observations of high-J CO transitions in the protoplanetary nebula CRL 618			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L3 (1 to 5)
	Keywords	HEB mixer applications, HIFI, Herschel
	Abstract	Aims. We aim to study the physical conditions, particularly the excitation state, of the intermediate-temperature gas components in the protoplanetary nebula CRL 618. These components are particularly important for understanding the evolution of the nebula. Methods. We performed Herschel/HIFI observations of several CO lines in the far-infrared/sub-mm in the protoplanetary nebula CRL 618. The high spectral resolution provided by HIFI allows measurement of the line profiles. Since the dynamics and structure of the nebula is well known from mm-wave interferometric maps, it is possible to identify the contributions of the different nebular components (fast bipolar outflows, double shells, compact slow shell) to the line profiles. The observation of these relatively high-energy transitions allows an accurate study of the excitation conditions in these components, particularly in the warm ones, which cannot be properly studied from the low-energy lines. Results. The 12CO J = 16–15, 10–9, and 6–5 lines are easily detected in this source. Both 13CO J = 10–9 and 6–5 are also detected. Wide profiles showing spectacular line wings have been found, particularly in 12CO J = 16–15. Other lines observed simultaneously with CO are also shown. Our analysis of the CO high-J transitions, when compared with the existing models, confirms the very low expansion velocity of the central, dense component, which probably indicates that the shells ejected during the last AGB phases were driven by radiation pressure under a regime of maximum transfer of momentum. No contribution of the diffuse halo found from mm-wave data is identified in our spectra, because of its low temperature. We find that the fast bipolar outflow is quite hot, much hotter than previously estimated; for instance, gas flowing at 100 km s-1 must have a temperature higher than ~200 K. Probably, this very fast outflow, with a kinematic age <100 yr, has been accelerated by a shock and has not yet cooled down. The double empty shell found from mm-wave mapping must also be relatively hot, in agreement with the previous estimate.
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	Notes				Approved	no
	Call Number				Serial	1084
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	Author	Cavalié, T.; Feuchtgruber, H.; Lellouch, E.; de Val-Borro, M.; Jarchow, C.; Moreno, R.; Hartogh, P.; Orton, G.; Greathouse, T. K.; Billebaud, F.; Dobrijevic, M.; Lara, L. M.; González, A.; Sagawa, H.
	Title	Spatial distribution of water in the stratosphere of Jupiter from Herschel HIFI and PACS observations			Type	Journal Article
	Year	2013	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	553	Issue		Pages	A21 (1 to 16)
	Keywords	HEB mixer applications, HIFI, Herschel
	Abstract	Context. In the past 15 years, several studies suggested that water in the stratosphere of Jupiter originated from the Shoemaker-Levy 9 (SL9) comet impacts in July 1994, but a direct proof was missing. Only a very sensitive instrument observing with high spectral/spatial resolution can help to solve this problem. This is the case of the Herschel Space Observatory, which is the first telescope capable of mapping water in Jupiter's stratosphere. Aims. We observed the spatial distribution of the water emission in Jupiter's stratosphere with the Heterodyne Instrument for the Far Infrared (HIFI) and the Photodetector Array Camera and Spectrometer (PACS) onboard Herschel to constrain its origin. In parallel, we monitored Jupiter's stratospheric temperature with the NASA Infrared Telescope Facility (IRTF) to separate temperature from water variability. Methods. We obtained a 25-point map of the 1669.9 GHz water line with HIFI in July 2010 and several maps with PACS in October 2009 and December 2010. The 2010 PACS map is a 400-point raster of the water 66.4 μm emission. Additionally, we mapped the methane Î½4 band emission to constrain the stratospheric temperature in Jupiter in the same periods with the IRTF. Results. Water is found to be restricted to pressures lower than 2 mbar. Its column density decreases by a factor of 2–3 between southern and northern latitudes, consistently between the HIFI and the PACS 66.4 μm maps. We infer that an emission maximum seen around 15 °S is caused by a warm stratospheric belt detected in the IRTF data. Conclusions. Latitudinal temperature variability cannot explain the global north-south asymmetry in the water maps. From the latitudinal and vertical distributions of water in Jupiter's stratosphere, we rule out interplanetary dust particles as its main source. Furthermore, we demonstrate that Jupiter's stratospheric water was delivered by the SL9 comet and that more than 95% of the observed water comes from the comet according to our models.
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	Notes				Approved	no
	Call Number				Serial	1085
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	Author	Chavarr'ıa, L.; Herpin, F.; Jacq, T.; Braine, J.; Bontemps, S.; Baudry, A.; Marseille, M.; van der Tak, F.; Pietropaoli, B.; Wyrowski, F.; Shipman, R.; Frieswijk, W.; van Dishoeck, E. F.; Cernicharo, J.; Bachiller, R.; Benedettini, M.; Benz, A. O.; Bergin, E.; Bjerkeli, P.; Blake, G. A.; Bruderer, S.; Caselli, P.; Codella, C.; Daniel, F.; di Giorgio, A. M.; Dominik, C.; Doty, S. D.; Encrenaz, P.; Fich, M.; Fuente, A.; Giannini, T.; Goicoechea, J. R.; de Graauw, T.; Hartogh, P.; Helmich, F.; Herczeg, G. J.; Hogerheijde, M. R.; Johnstone, D.; Jørgensen, J. K.; Kristensen, L. E.; Larsson, B.; Lis, D.; Liseau, R.; McCoey, C.; Melnick, G.; Nisini, B.; Olberg, M.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago-Garc'ıa, J.; Saraceno, P.; Stutzki, J.; Szczerba, R.; Tafalla, M.; Tielens, A.; van Kempen, T. A.; Visser, R.; Wampfler, S. F.; Willem, J.; Yıldız, U. A.
	Title	Water in massive star-forming regions: HIFI observations of W3 IRS5			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L37 (1 to 5)
	Keywords	HEB mixer applications, HIFI, Herschel, stars: formation, stars: massive, ISM: molecules, ISM: abundances, dust, extinction, radio lines: ISM
	Abstract	We present Herschel observations of the water molecule in the massive star-forming region W3 IRS5. The o-H217O 110-101, p-H218O 111-000, p-H2O 202-111, p-H2O 111-000, o-H2O 221-212, and o-H2O 212-101 lines, covering a frequency range from 552 up to 1669 GHz, have been detected at high spectral resolution with HIFI. The water lines in W3 IRS5 show well-defined high-velocity wings that indicate a clear contribution by outflows. Moreover, the systematically blue-shifted absorption in the H2O lines suggests expansion, presumably driven by the outflow. No infall signatures are detected. The p-H2O 111-000 and o-H2O 212-101 lines show absorption from the cold material (T ~ 10 K) in which the high-mass protostellar envelope is embedded. One-dimensional radiative transfer models are used to estimate water abundances and to further study the kinematics of the region. We show that the emission in the rare isotopologues comes directly from the inner parts of the envelope (T â‰<b3> 100 K) where water ices in the dust mantles evaporate and the gas-phase abundance increases. The resulting jump in the water abundance (with a constant inner abundance of 10-4) is needed to reproduce the o-H217O 110-101 and p-H218O 111-000 spectra in our models. We estimate water abundances of 10-8 to 10-9 in the outer parts of the envelope (T â‰<b2> 100 K). The possibility of two protostellar objects contributing to the emission is discussed.
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	Call Number	Chav13HEBapplHIFIb			Serial	1086
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	Author	Crockett, N. R.; Bergin, E. A.; Wang, S.; Lis, D. C.; Bell, T. A.; Blake, G. A.; Boogert, A.; Bumble, B.; Cabrit, S.; Caux, E.; Ceccarelli, C.; Cernicharo, J.; Comito, C.; Daniel, F.; Dubernet, M.-L.; Emprechtinger, M.; Encrenaz, P.; Falgarone, E.; Gerin, M.; Giesen, T. F.; Goicoechea, J. R.; Goldsmith, P. F.; Gupta, H.; Güsten, R.; Hartogh, P.; Helmich, F.; Herbst, E.; Honingh, N.; Joblin, C.; Johnstone, D.; Karpov, A.; Kawamura, J. H.; Kooi, J.; Krieg, J.-M.; Langer, W. D.; Latter, W. D.; Lord, S. D.; Maret, S.; Martin, P. G.; Melnick, G. J.; Menten, K. M.; Morris, P.; Müller, H. S. P.; Murphy, J. A.; Neufeld, D. A.; Ossenkopf, V.; Pearson, J. C.; Pérault, M.; Phillips, T. G.; Plume, R.; Qin, S.-L.; Roelfsema, P.; Schieder, R.; Schilke, P.; Schlemmer, S.; Stutzki, J.; van der Tak, F. F. S.; Tielens, A.; Trappe, N.; Vastel, C.; Yorke, H. W.; Yu, S.; Zmuidzinas, J.
	Title	Herschel observations of EXtra-Ordinary Sources (HEXOS): The Terahertz spectrum of Orion KL seen at high spectral resolution			Type	Journal Article
	Year	2010	Publication	Annual Rev. Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L21 (1 to 5)
	Keywords	HEB mixer applications, HIFI, Herschel
	Abstract	We present the first high spectral resolution observations of Orion KL in the frequency ranges 1573.4–1702.8 GHz (band 6b) and 1788.4–1906.8 GHz (band 7b) obtained using the HIFI instrument on board the Herschel Space Observatory. We characterize the main emission lines found in the spectrum, which primarily arise from a range of components associated with Orion KL including the hot core, but also see widespread emission from components associated with molecular outflows traced by H2O, SO2, and OH. We find that the density of observed emission lines is significantly diminished in these bands compared to lower frequency Herschel/HIFI bands.
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	Notes				Approved	no
	Call Number				Serial	1087
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	Author	Hartogh, P.; Crovisier, J.; de Val-Borro, M.; Bockelée-Morvan, D.; Biver, N.; Lis, D. C.; Moreno, R.; Jarchow, C.; Rengel, M.; Emprechtinger, M.; Szutowicz, S.; Banaszkiewicz, M.; Bensch, F.; Blecka, M. I.; Cavalié, T.; Encrenaz, T.; Jehin, E.; Küppers, M.; Lara, L.-M.; Lellouch, E.; Swinyard, B. M.; Vandenbussche, B.; Bergin, E. A.; Blake, G. A.; Blommaert, J. A. D. L.; Cernicharo, J.; Decin, L.; Encrenaz, P.; de Graauw, T.; Hutsemekers, D.; Kidger, M.; Manfroid, J.; Medvedev, A. S.; Naylor, D. A.; Schieder, R.; Thomas, N.; Waelkens, C.; Roelfsema, P. R.; Dieleman, P.; Güsten, R.; Klein, T.; Kasemann, C.; Caris, M.; Olberg, M.; Benz, A. O.
	Title	HIFI observations of water in the atmosphere of comet C/2008 Q3 (Garradd)			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	518	Issue		Pages	L150 (1 to 5)
	Keywords	HEB mixer applications, HIFI, Herschel, comets: individual: C/2008 Q3 / radio lines: general / submillimeter: general / techniques: spectroscopic
	Abstract	High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres. We present observations of several rotational ortho- and para-water transitions in comet C/2008 Q3 (Garradd) performed with HIFI on Herschel. These observations have provided the first detection of the 212–101 (1669 GHz) ortho and 111–000 (1113 GHz) para transitions of water in a cometary spectrum. In addition, the ground-state transition 110–101 at 557 GHz is detected and mapped. By detecting several water lines quasi-simultaneously and mapping their emission we can constrain the excitation parameters in the coma. Synthetic line profiles are computed using excitation models which include excitation by collisions, solar infrared radiation, and radiation trapping. We obtain the gas kinetic temperature, constrain the electron density profile, and estimate the coma expansion velocity by analyzing the map and line shapes. We derive water production rates of 1.7–2.8 × 1028 s-1 over the range rh = 1.83–1.85 AU.
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	Notes				Approved	no
	Call Number				Serial	1088
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	Author	Decin, L.; Justtanont, K.; De Beck, E.; Lombaert, R.; de Koter, A.; Waters, L. B. F. M.; Marston, A. P.; Teyssier, D.; Schöier, F. L.; Bujarrabal, V.; Alcolea, J.; Cernicharo, J.; Dominik, C.; Melnick, G.; Menten, K.; Neufeld, D. A.; Olofsson, H.; Planesas, P.; Schmidt, M.; Szczerba, R.; de Graauw, T.; Helmich, F.; Roelfsema, P.; Dieleman, P.; Morris, P.; Gallego, J. D.; Díez-González, M. C.; Caux, E.
	Title	Water content and wind acceleration in the envelope around the oxygen-rich AGB star IK Tauri as seen by Herschel/HIFI			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L4
	Keywords	HEB mixer applications, HIFI, Herschel, line: profiles / radiative transfer / instrumentation: spectrographs / stars: AGB and post-AGB / circumstellar matter / submillimeter: stars
	Abstract	During their asymptotic giant branch evolution, low-mass stars lose a significant fraction of their mass through an intense wind, enriching the interstellar medium with products of nucleosynthesis. We observed the nearby oxygen-rich asymptotic giant branch star IK Tau using the high-resolution HIFI spectrometer onboard Herschel. We report on the first detection of H216O and the rarer isotopologues H217O and H218O in both the ortho and para states. We deduce a total water content (relative to molecular hydrogen) of $6.6 \times 10^{-5}$, and an ortho-to-para ratio of 3:1. These results are consistent with the formation of H2O in thermodynamical chemical equilibrium at photospheric temperatures, and does not require pulsationally induced non-equilibrium chemistry, vaporization of icy bodies or grain surface reactions. High-excitation lines of 12CO, 13CO, 28SiO, 29SiO, 30SiO, HCN, and SO have also been detected. From the observed line widths, the acceleration region in the inner wind zone can be characterized, and we show that the wind acceleration is slower than hitherto anticipated.
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	Notes				Approved	no
	Call Number				Serial	1090
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	Author	Dedes, C.; Röllig, M.; Mookerjea, B.; Okada, Y.; Ossenkopf, V.; Bruderer, S.; Benz, A. O.; Melchior, M.; Kramer, C.; Gerin, M.; Güsten, R.; Akyilmaz, M.; Berne, O.; Boulanger, F.; De Lange, G.; Dubbeldam, L.; France, K.; Fuente, A.; Goicoechea, J. R.; Harris, A.; Huisman, R.; Jellema, W.; Joblin, C.; Klein, T.; Le Petit, F.; Lord, S.; Martin, P.; Martin-Pintado, J.; Neufeld, D. A.; Philipp, S.; Phillips, T.; Pilleri, P.; Rizzo, J. R.; Salez, M.; Schieder, R.; Simon, R.; Siebertz, O.; Stutzki, J.; van der Tak, F.; Teyssier, D.; Yorke, H.
	Title	The origin of the [C II] emission in the S140 photon-dominated regions. New insights from HIFI			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L24
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: structure / ISM: kinematics and dynamics / ISM: molecules / photon-dominated region (PDR) / submillimeter: general
	Abstract	Using Herschel's HIFI instrument, we observe C ii along a cut through S140, as well as high-J transitions of CO and HCO+ at two positions on the cut, corresponding to the externally irradiated ionization front and the embedded massive star-forming core IRS1. The HIFI data were combined with available ground-based observations and modeled using the KOSMA-Ï„ model for photon-dominated regions (PDRs). We derive the physical conditions in S140 and in particular the origin of C ii emission around IRS1. We identify three distinct regions of C ii emission from the cut, one close to the embedded source IRS1, one associated with the ionization front, and one further into the cloud. The line emission can be understood in terms of a clumpy model of PDRs. At the position of IRS1, we identify at least two distinct components contributing to the [C ii] emission, one of them a small, hot component, which can possibly be identified with the irradiated outflow walls. This is consistent with the C ii peak at IRS1 coinciding with shocked H2 emission at the edges of the outflow cavity. We note that previously available observations of IRS1 can be reproduced well by a single-component KOSMA-Ï„ model. Thus, it is HIFI's unprecedented spatial and spectral resolution, as well as its sensitivity that has allowed us to uncover an additional hot gas component in the S140 region.
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	Notes				Approved	no
	Call Number				Serial	1091
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	Author	De Luca, M.; Gupta, H.; Neufeld, D.; Gerin, M.; Teyssier, D.; Drouin, B. J.; Pearson, J. C.; Lis, D. C.; Monje, R.; Phillips, T. G.; Goicoechea, J. R.; Godard, B.; Falgarone, E.; Coutens, A.; Bell, T. A.
	Title	Herschel/HIFI discovery of HCL+ in the interstellar medium			Type	Journal Article
	Year	2012	Publication	Astrophys. J. Lett.	Abbreviated Journal
	Volume	751	Issue	2	Pages	L37
	Keywords	HEB mixer applications, HIFI, Herschel
	Abstract	The radical ion HCl+, a key intermediate in the chlorine chemistry of the interstellar gas, has been identified for the first time in the interstellar medium with the Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared. The ground-state rotational transition of H35Cl+, 2Î 3/2 J = 5/2-3/2, showing Î›-doubling and hyperfine structure, is detected in absorption toward the Galactic star-forming regions W31C (G10.6-0.4) and W49N. The complex interstellar absorption features are modeled by convolving in velocity space the opacity profiles of other molecular tracers toward the same sources with the fine and hyperfine structure of HCl+. This structure is derived from a combined analysis of optical data from the literature and new laboratory measurements of pure rotational transitions, reported in the accompanying Letter by Gupta et al. The models reproduce well the interstellar absorption, and the frequencies inferred from the astronomical observations are in exact agreement with those calculated using spectroscopic constants derived from the laboratory data. The detection of H37Cl+ toward W31C, with a column density consistent with the expected 35Cl/37Cl isotopic ratio, provides additional evidence for the identification. A comparison with the chemically related molecules HCl and H2Cl+ yields an abundance ratio of unity with both species (HCl+ : H2Cl+ : HCl ~ 1). These observations also yield the unexpected result that HCl+ accounts for 3%-5% of the gas-phase chlorine toward W49N and W31C, values several times larger than the maximum fraction (~1%) predicted by chemical models.
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	Notes				Approved	no
	Call Number				Serial	1092
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	Author	Hartogh, P.; Jarchow, C.; Lellouch, E.; de Val-Borro, M.; Rengel, M.; Moreno, R.; Medvedev, A. S.; Sagawa, H.; Swinyard, B. M.; Cavalié, T.; Lis, D. C.; BłÄ™cka, M. I.; Banaszkiewicz, M.; Bockelée-Morvan, D.; Crovisier, J.; Encrenaz, T.; Küppers, M.; Lara, L.-M.; Szutowicz, S.; Vandenbussche, B.; Bensch, F.; Bergin, E. A.; Billebaud, F.; Biver, N.; Blake, G. A.; Blommaert, J. A. D. L.; Cernicharo, J.; Decin, L.; Encrenaz, P.; Feuchtgruber, H.; Fulton, T.; de Graauw, T.; Jehin, E.; Kidger, M.; Lorente, R.; Naylor, D. A.; Portyankina, G.; Sánchez-Portal, M.; Schieder, R.; Sidher, S.; Thomas, N.; Verdugo, E.; Waelkens, C.; Whyborn, N.; Teyssier, D.; Helmich, F.; Roelfsema, P.; Stutzki, J.; LeDuc, H. G.; Stern, J. A.
	Title	Herschel/HIFI observations of Mars: First detection of O₂ at submillimetre wavelengths and upper limits on HCl and H₂O₂			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L49
	Keywords	HEB mixer applications, HIFI, Herschel, planets and satellites: atmospheres / radiative transfer / submillimeter: general / molecular processes
	Abstract	We report on an initial analysis of Herschel/HIFI observations of hydrogen chloride (HCl), hydrogen peroxide (H2O2), and molecular oxygen (O2) in the Martian atmosphere performed on 13 and 16 April 2010 (Ls ~ 77°). We derived a constant volume mixing ratio of 1400 ± 120 ppm for O2 and determined upper limits of 200 ppt for HCl and 2 ppb for H2O2. Radiative transfer model calculations indicate that the vertical profile of O2 may not be constant. Photochemical models determine the lowest values of H2O2 to be around Ls ~ 75° but overestimate the volume mixing ratio compared to our measurements.
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	Notes				Approved	no
	Call Number				Serial	1093
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	Author	Maret, S.; Bacmann, A.; Bottinelli, S.; Parise, B.; Caux, E.; Faure, A.; Bergin, E. A.; Blake, G. A.; Castets, A.; Ceccarelli, C.; Cernicharo, J.; Coutens, A.; Crimier, N.; Demyk, K.; Dominik, C.; Gerin, M.; Hennebelle, P.; Henning, T.; Kahane, C.; Klotz, A.; Melnick, G.; Pagani, L.; Schilke, P.; Vastel, C.; Wakelam, V.; Walters, A.; Baudry, A.; Bell, T.; Benedettini, M.; Boogert, A.; Cabrit, S.; Caselli, P.; Codella, C.; Comito, C.; Encrenaz, P.; Falgarone, E.; Fuente, A.; Goldsmith, P. F.; Helmich, F.; Herbst, E.; Jacq, T.; Kama, M.; Langer, W.; Lefloch, B.; Lis, D.; Lord, S.; Lorenzani, A.; Neufeld, D.; Nisini, B.; Pacheco, S.; Phillips, T.; Salez, M.; Saraceno, P.; Schuster, K.; Tielens, X.; van der Tak, F.; van der Wiel, M. H. D.; Viti, S.; Wyrowski, F.; Yorke, H.
	Title	Nitrogen hydrides in the cold envelope of IRAS 16293-2422			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L52
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: abundances / ISM: general / astrochemistry
	Abstract	Nitrogen is the fifth most abundant element in the Universe, yet the gas-phase chemistry of N-bearing species remains poorly understood. Nitrogen hydrides are key molecules of nitrogen chemistry. Their abundance ratios place strong constraints on the production pathways and reaction rates of nitrogen-bearing molecules. We observed the class 0 protostar IRAS 16293-2422 with the heterodyne instrument HIFI, covering most of the frequency range from 0.48 to 1.78 THz at high spectral resolution. The hyperfine structure of the amidogen radical o-NH2 is resolved and seen in absorption against the continuum of the protostar. Several transitions of ammonia from 1.2 to 1.8 THz are also seen in absorption. These lines trace the low-density envelope of the protostar. Column densities and abundances are estimated for each hydride. We find that NH:NH2:NH3 â‰<2c6> 5:1:300. Dark clouds chemical models predict steady-state abundances of NH2 and NH3 in reasonable agreement with the present observations, whilst that of NH is underpredicted by more than one order of magnitude, even using updated kinetic rates. Additional modelling of the nitrogen gas-phase chemistry in dark-cloud conditions is necessary before having recourse to heterogen processes.
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	Notes				Approved	no
	Call Number				Serial	1094
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	Author	Joblin, C.; Pilleri, P.; Montillaud, J.; Fuente, A.; Gerin, M.; Berné, O.; Ossenkopf, V.; Le Bourlot, J.; Teyssier, D.; Goicoechea, J. R.; Le Petit, F.; Röllig, M.; Akyilmaz, M.; Benz, A. O.; Boulanger, F.; Bruderer, S.; Dedes, C.; France, K.; Güsten, R.; Harris, A.; Klein, T.; Kramer, C.; Lord, S. D.; Martin, P. G.; Martin-Pintado, J.; Mookerjea, B.; Okada, Y.; Phillips, T. G.; Rizzo, J. R.; Simon, R.; Stutzki, J.; van der Tak, F.; Yorke, H. W.; Steinmetz, E.; Jarchow, C.; Hartogh, P.; Honingh, C. E.; Siebertz, O.; Caux, E.; Colin, B.
	Title	Gas morphology and energetics at the surface of PDRs: New insights with Herschel observations of NGC 7023			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L25
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: structure / ISM: kinematics and dynamics / ISM: molecules / submillimeter: ISM
	Abstract	Context. We investigate the physics and chemistry of the gas and dust in dense photon-dominated regions (PDRs), along with their dependence on the illuminating UV field. Aims. Using Herschel/HIFI observations, we study the gas energetics in NGC 7023 in relation to the morphology of this nebula. NGC 7023 is the prototype of a PDR illuminated by a B2V star and is one of the key targets of Herschel. Methods. Our approach consists in determining the energetics of the region by combining the information carried by the mid-IR spectrum (extinction by classical grains, emission from very small dust particles) with that of the main gas coolant lines. In this letter, we discuss more specifically the intensity and line profile of the 158 μm (1901 GHz) [C ii] line measured by HIFI and provide information on the emitting gas. Results. We show that both the [C ii] emission and the mid-IR emission from polycyclic aromatic hydrocarbons (PAHs) arise from the regions located in the transition zone between atomic and molecular gas. Using the Meudon PDR code and a simple transfer model, we find good agreement between the calculated and observed [C ii] intensities. Conclusions. HIFI observations of NGC 7023 provide the opportunity to constrain the energetics at the surface of PDRs. Future work will include analysis of the main coolant line [O i] and use of a new PDR model that includes PAH-related species.
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	Notes				Approved	no
	Call Number				Serial	1095
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	Author	Justtanont, K.; Decin, L.; Schöier, F. L.; Maercker, M.; Olofsson, H.; Bujarrabal, V.; Marston, A. P.; Teyssier, D.; Alcolea, J.; Cernicharo, J.; Dominik, C.; de Koter, A.; Melnick, G.; Menten, K.; Neufeld, D.; Planesas, P.; Schmidt, M.; Szczerba, R.; Waters, R.; de Graauw, Th.; Whyborn, N.; Finn, T.; Helmich, F.; Siebertz, O.; Schmülling, F.; Ossenkopf, V.; Lai, R.
	Title	A HIFI preview of warm molecular gas around Ï‡ Cygni: first detection of H2O emission toward an S-type AGB star			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L6
	Keywords	HEB mixer applications, HIFI, Herschel, stars: AGB and post-AGB / circumstellar matter / stars: kinematics and dynamics / stars: individual: Ï‡ Cyg / stars: late-type / stars: mass-loss
	Abstract	Aims. A set of new, sensitive, and spectrally resolved, sub-millimeter line observations are used to probe the warm circumstellar gas around the S-type AGB star Ï‡ Cyg. The observed lines involve high rotational quantum numbers, which, combined with previously obtained lower-frequency data, make it possible to study in detail the chemical and physical properties of, essentially, the entire circumstellar envelope of Ï‡ Cyg. Methods. The data were obtained using the HIFI instrument aboard Herschel, whose high spectral resolution provides valuable information about the line profiles. Detailed, non-LTE, radiative transfer modelling, including dust radiative transfer coupled with a dynamical model, has been performed to derive the temperature, density, and velocity structure of the circumstellar envelope. Results. We report the first detection of circumstellar H2O rotational emission lines in an S-star. Using the high-J CO lines to derive the parameters for the circumstellar envelope, we modelled both the ortho- and para-H2O lines. Our modelling results are consistent with the velocity structure expected for a dust-driven wind. The derived total H2O abundance (relative to H2) is (1.1±0.2) × 10-5, much lower than that in O-rich stars. The derived ortho-to-para ratio of 2.1±0.6 is close to the high-temperature equilibrium limit, consistent with H2O being formed in the photosphere.
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	Notes				Approved	no
	Call Number				Serial	1096
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	Author	Loenen, A. F.; van der Werf, P. P.; Güsten, R.; Meijerink, R.; Israel, F. P.; Requena-Torres, M. A.; García-Burillo, S.; Harris, A. I.; Klein, T.; Kramer, C.; Lord, S.; Martín-Pintado, J.; Röllig, M.; Stutzki, J.; Szczerba, R.; WeiÃŸ, A.; Philipp-May, S.; Yorke, H.; Caux, E.; Delforge, B.; Helmich, F.; Lorenzani, A.; Morris, P.; Philips, T. G.; Risacher, C.; Tielens, A. G. G. M.
	Title	Excitation of the molecular gas in the nuclear region of M 82			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L2
	Keywords	HEB mixer applications, HIFI, Herschel, galaxies: individual: M 82 / submillimeter: ISM / ISM: molecules / galaxies: ISM / galaxies: starburst
	Abstract	We present high-resolution HIFI spectroscopy of the nucleus of the archetypical starburst galaxy M 82. Six 12COâ€€lines, 2 13COâ€€lines and 4 fine-structure lines have been detected. Besides showing the effects of the overall velocity structure of the nuclear region, the line profiles also indicate the presence of multiple components with different optical depths, temperatures, and densities in the observing beam. The data have been interpreted using a grid of PDR models. It is found that the majority of the molecular gas is in low density (n = 103.5 cm-3) clouds, with column densities of NH = 1021.5 cm-2 and a relatively low UV radiation field (G0 = 102). The remaining gas is predominantly found in clouds with higher densities (n = 105 cm-3) and radiation fields (G0 = 102.75), but somewhat lower column densities (NH = 1021.2 cm-2). The highest J CO lines are dominated by a small (1% relative surface filling) component, with an even higher density (n = 106 cm-3) and UV field (G0 = 103.25). These results show the strength of multi-component modelling for interpretating the integrated properties of galaxies.
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	Notes				Approved	no
	Call Number				Serial	1097
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	Author	Melnick, G. J.; Tolls, V.; Neufeld, D. A.; Bergin, E. A.; Phillips, T. G.; Wang, S.; Crockett, N. R.; Bell, T. A.; Blake, G. A.; Cabrit, S.; Caux, E.; Ceccarelli, C.; Cernicharo, J.; Comito, C.; Daniel, F.; Dubernet, M.-L.; Emprechtinger, M.; Encrenaz, P.; Falgarone, E.; Gerin, M.; Giesen, T. F.; Goicoechea, J. R.; Goldsmith, P. F.; Herbst, E.; Joblin, C.; Johnstone, D.; Langer, W. D.; Latter, W. D.; Lis, D. C.; Lord, S. D.; Maret, S.; Martin, P. G.; Menten, K. M.; Morris, P.; Müller, H. S. P.; Murphy, J. A.; Ossenkopf, V.; Pagani, L.; Pearson, J. C.; Pérault, M.; Plume, R.; Qin, S.-L.; Salez, M.; Schilke, P.; Schlemmer, S.; Stutzki, J.; Trappe, N.; van der Tak, F. F. S.; Vastel, C.; Yorke, H. W.; Yu, S.; Zmuidzinas, J.
	Title	Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H₂O and its isotopologues towards Orion KL			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L27
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: abundances / ISM: molecules
	Abstract	We report the detection of more than 48 velocity-resolved ground rotational state transitions of H216O, H218O, and H217O – most for the first time – in both emission and absorption toward Orion KL using Herschel/HIFI. We show that a simple fit, constrained to match the known emission and absorption components along the line of sight, is in excellent agreement with the spectral profiles of all the water lines. Using the measured H218O line fluxes, which are less affected by line opacity than their H216O counterparts, and an escape probability method, the column densities of H218O associated with each emission component are derived. We infer total water abundances of 7.4 × 10-5, 1.0 × 10-5, and 1.6 × 10-5 for the plateau, hot core, and extended warm gas, respectively. In the case of the plateau, this value is consistent with previous measures of the Orion-KL water abundance as well as those of other molecular outflows. In the case of the hot core and extended warm gas, these values are somewhat higher than water abundances derived for other quiescent clouds, suggesting that these regions are likely experiencing enhanced water-ice sublimation from (and reduced freeze-out onto) grain surfaces due to the warmer dust in these sources.
	Address
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	Publisher		Place of Publication		Editor
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	Notes				Approved	no
	Call Number				Serial	1098
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	Author	Mookerjea, B.; Giesen, T.; Stutzki, J.; Cernicharo, J.; Goicoechea, J. R.; De Luca, M.; Bell, T. A.; Gupta, H.; Gerin, M.; Persson, C. M.; Sonnentrucker, P.; Makai, Z.; Black, J.; Boulanger, F.; Coutens, A.; Dartois, E.; Encrenaz, P.; Falgarone, E.; Geballe, T.; Godard, B.; Goldsmith, P. F.; Gry, C.; Hennebelle, P.; Herbst, E.; Hily-Blant, P.; Joblin, C.; Ka<c5><ba>mierczak, M.; Kołos, R.; Krełowski, J.; Lis, D. C.; Martin-Pintado, J.; Menten, K. M.; Monje, R.; Pearson, J. C.; Perault, M.; Phillips, T. G.; Plume, R.; Salez, M.; Schlemmer, S.; Schmidt, M.; Teyssier, D.; Vastel, C.; Yu, S.; Dieleman, P.; Güsten, R.; Honingh, C. E.; Morris, P.; Roelfsema, P.; Schieder, R.; Tielens, A. G. G. M.; Zmuidzinas, J.
	Title	Excitation and abundance of C3 in star forming cores. Herschel/HIFI observations of the sight-lines to W31C and W49N			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L13
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: lines and bands / ISM: molecules / radiative transfer / ISM: individual objects: W49N / ISM: individual objects: W31C
	Abstract	We present spectrally resolved observations of triatomic carbon (C3) in several ro-vibrational transitions between the vibrational ground state and the low-energy Î½2 bending mode at frequencies between 1654–1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C3 absorption due to diffuse foreground clouds. From the column densities of the rotational levels in the vibrational ground state probed by the absorption we derive a rotation temperature (Trot) of ~50-70 K, which is a good measure of the kinetic temperature of the absorbing gas, as radiative transitions within the vibrational ground state are forbidden. It is also in good agreement with the dust temperatures for W31C and W49N. Applying the partition function correction based on the derived Trot, we get column densities N(C3) ~ 7–9 × 1014 cm-2 and abundance x(C3) ~ 10-8 with respect to H2. For W31C, using a radiative transfer model including far-infrared pumping by the dust continuum and a temperature gradient within the source along the line of sight we find that a model with x(C3) = 10-8, Tkin = 30–50 K, N(C3) = 1.5 × 1015 cm-2 fits the observations reasonably well and provides parameters in very good agreement with the simple excitation analysis.
	Address
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	Notes				Approved	no
	Call Number				Serial	1099
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	Author	Pineda, J. L.; Langer, W. D.; Velusamy, T.; Goldsmith, P. F.
	Title	A Herschel [C ii] Galactic plane survey. I. The global distribution of ISM gas components			Type	Journal Article
	Year	2013	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	554	Issue		Pages	A103
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: general / stars: formation / evolution / ISM: clouds / ISM: structure / submillimeter: ISM
	Abstract	Context. The [C ii] 158 μm line is an important tool for understanding the life cycle of interstellar matter. Ionized carbon is present in a variety of phases of the interstellar medium (ISM), including the diffuse ionized medium, warm and cold atomic clouds, clouds in transition from atomic to molecular, and dense and warm photon dominated regions. Aims. Velocity-resolved observations of [C ii] are the most powerful technique available to disentangle the emission produced by these components. These observations can also be used to trace CO-dark H2 gas and determine the total mass of the ISM. Methods. The Galactic Observations of Terahertz C+ (GOT C+) project surveys the [C ii] 158 μm line over the entire Galactic disk with velocity-resolved observations using the Herschel/HIFI instrument. We present the first longitude-velocity maps of the [C ii] emission for Galactic latitudes b = 0°, ±0.5°, and ±1.0°. We combine these maps with those of H i, 12CO, and 13CO to separate the different phases of the ISM and study their properties and distribution in the Galactic plane. Results. [C ii] emission is mostly associated with spiral arms, mainly emerging from Galactocentric distances between 4 and 10 kpc. It traces the envelopes of evolved clouds as well as clouds that are in the transition between atomic and molecular. We estimate that most of the observed [C ii] emission is produced by dense photon dominated regions (~47%), with smaller contributions from CO-dark H2 gas (~28%), cold atomic gas (~21%), and ionized gas (~4%). Atomic gas inside the Solar radius is mostly in the form of cold neutral medium (CNM), while the warm neutral medium gas dominates the outer galaxy. The average fraction of CNM relative to total atomic gas is ~43%. We find that the warm and diffuse CO-dark H2 is distributed over a larger range of Galactocentric distances (4–11 kpc) than the cold and dense H2 gas traced by 12CO and 13CO (4–8 kpc). The fraction of CO-dark H2 to total H2 increases with Galactocentric distance, ranging from ~20% at 4 kpc to ~80% at 10 kpc. On average, CO-dark H2 accounts for ~30% of the molecular mass of the Milky Way. When the CO-dark H2 component is included, the radial distribution of the CO-to-H2 conversion factor is steeper than that when only molecular gas traced by CO is considered. Most of the observed [C ii] emission emerging from dense photon dominated regions is associated with modest far-ultraviolet fields in the range Ï‡0 â‰<192> 1 – 30.
	Address
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	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
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	Notes				Approved	no
	Call Number				Serial	1100
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	Author	Pineda, J. L.; Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Li, D.; Yorke, H. W.
	Title	A sample of [C II] clouds tracing dense clouds in weak FUV fields observed by Herschel			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L19
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: structure / photon-dominated region / ISM: supernova remnants / evolution
	Abstract	The [C ii] fine-structure line at 158 μm is an excellent tracer of the warm diffuse gas in the ISM and the interfaces between molecular clouds and their surrounding atomic and ionized envelopes. Here we present the initial results from Galactic observations of terahertz C+ (GOT C+), a Herschel key project devoted to studying the [C ii] emission in the Galactic plane using the HIFI instrument. We used the [C ii] emission, together with observations of CO, as a probe to understand the effects of newly formed stars on their interstellar environment and characterize the physical and chemical state of the star-forming gas. We collected data along 16 lines-of-sight passing near star-forming regions in the inner Galaxy near longitudes 330° and 20°. We identified fifty-eight [C ii] components that are associated with high-column density molecular clouds as traced by 13CO emission. We combined [C ii], 12CO, and 13CO observations to derive the physical conditions of the [C ii]-emitting regions in our sample of high-column density clouds based on comparing results from a grid of photon dominated region (PDR) models. From this unbiased sample, our results suggest that most of the [C ii] emission originates in clouds with H2 volume densities between 103.5 and 105.5 cm-3 and weak FUV strength (Ï‡0 = 1–10). We find two regions where our analysis suggest high densities >105 cm-3 and strong FUV fields (Ï‡0 = 104–106), likely associated with massive star formation. We suggest that [C ii] emission in conjunction with CO isotopes is a good tool for differentiating regions of massive star formation (high densities/strong FUV fields) and regions that are distant from massive stars (lower densities/weaker FUV fields) along the line-of-sight.
	Address
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	Notes				Approved	no
	Call Number				Serial	1101
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	Author	Velusamy, T.; Langer, W. D.; Pineda, J. L.; Goldsmith, P. F.; Li, D.; Yorke, H. W.
	Title	[CII] observations of H₂ molecular layers in transition clouds			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L18
	Keywords	HEB mixer applications, HIFI, Herschel, ISM: structure / ISM: molecules / ISM: atoms / submillimeter: ISM
	Abstract	We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 μm (1.9 THz) towards Galactic longitudes near 340° (5 LOSs) & 20° (11 LOSs) as part of the HIFI tests and GOT C+ survey. Out of the total 146 [CII] velocity components detected by profile fitting we identify 53 as diffuse molecular clouds with associated 12CO emission but without 13CO emission and characterized by AV < 5 mag. We estimate the fraction of the [CII] emission in the diffuse HI layer in each cloud and then determine the [CII] emitted from the molecular layers in the cloud. We show that the excess [CII] intensities detected in a few clouds is indicative of a thick H2 layer around the CO core. The wide range of clouds in our sample with thin to thick H2 layers suggests that these are at various evolutionary states characterized by the formation of H2 and CO layers from HI and C+, respectively. In about 30% of the clouds the H2 column densities (â€œdark gasâ€) traced by the [CII] is 50% or more than that traced by 12CO emission. On the average ~25% of the total H2 in these clouds is in an H2 layer which is not traced by CO. We use the HI, [CII], and 12CO intensities in each cloud along with simple chemical models to obtain constraints on the FUV fields and cosmic ray ionization rates.
	Address
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	Notes				Approved	no
	Call Number				Serial	1102
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	Author	Wampfler, S. F.; Herczeg, G. J.; Bruderer, S.; Benz, A. O.; van Dishoeck, E. F.; Kristensen, L. E.; Visser, R.; Doty, S. D.; Melchior, M.; van Kempen, T. A.; Yıldız, U. A.; Dedes, C.; Goicoechea, J. R.; Baudry, A.; Melnick, G.; Bachiller, R.; Benedettini, M.; Bergin, E.; Bjerkeli, P.; Blake, G. A.; Bontemps, S.; Braine, J.; Caselli, P.; Cernicharo, J.; Codella, C.; Daniel, F.; di Giorgio, A. M.; Dominik, C.; Encrenaz, P.; Fich, M.; Fuente, A.; Giannini, T.; de Graauw, Th.; Helmich, F.; Herpin, F.; Hogerheijde, M. R.; Jacq, T.; Johnstone, D.; Jørgensen, J. K.; Larsson, B.; Lis, D.; Liseau, R.; Marseille, M.; Mc Coey, C.; Neufeld, D.; Nisini, B.; Olberg, M.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago-García, J.; Saraceno, P.; Shipman, R.; Tafalla, M.; van der Tak, F. F. S.; Wyrowski, F.; Roelfsema, P.; Jellema, W.; Dieleman, P.; Caux, E.; Stutzki, J.
	Title	Herschel observations of the hydroxyl radical (OH) in young stellar objects			Type	Journal Article
	Year	2010	Publication	Astron. Astrophys.	Abbreviated Journal
	Volume	521	Issue		Pages	L36
	Keywords	HEB mixer applications, HIFI, Herschel, astrochemistry / stars: formation / ISM: molecules / ISM: jets and outflows / ISM: individual objects: HH 46
	Abstract	Aims. â€œWater In Star-forming regions with Herschelâ€ (WISH) is a Herschel key program investigating the water chemistry in young stellar objects (YSOs) during protostellar evolution. Hydroxyl (OH) is one of the reactants in the chemical network most closely linked to the formation and destruction of H2O. High-temperature (T 250 K) chemistry connects OH and H2O through the OH + H2 H2O + H reactions. Formation of H2O from OH is efficient in the high-temperature regime found in shocks and the innermost part of protostellar envelopes. Moreover, in the presence of UV photons, OH can be produced from the photo-dissociation of H2O through H2O + γUV OH + H. Methods. High-resolution spectroscopy of the 163.12 μm triplet of OH towards HH 46 and NGC 1333 IRAS 2A was carried out with the Heterodyne Instrument for the Far Infrared (HIFI) on board the Herschel Space Observatory. The low- and intermediate-mass protostars HH 46, TMR 1, IRAS 15398-3359, DK Cha, NGC 7129 FIRS 2, and NGC 1333 IRAS 2A were observed with the Photodetector Array Camera and Spectrometer (PACS) on Herschel in four transitions of OH and two [O i] lines. Results. The OH transitions at 79, 84, 119, and 163 μm and [O i] emission at 63 and 145μm were detected with PACS towards the class I low-mass YSOs as well as the intermediate-mass and class I Herbig Ae sources. No OH emission was detected from the class 0 YSO NGC 1333 IRAS 2A, though the 119 μm was detected in absorption. With HIFI, the 163.12 μm was not detected from HH 46 and only tentatively detected from NGC 1333 IRAS 2A. The combination of the PACS and HIFI results for HH 46 constrains the line width (FWHM 11 km s-1) and indicates that the OH emission likely originates from shocked gas. This scenario is supported by trends of the OH flux increasing with the [O i] flux and the bolometric luminosity, as found in our sample. Similar OH line ratios for most sources suggest that OH has comparable excitation temperatures despite the different physical properties of the sources.
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	Call Number				Serial	1103
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	Author	Shcherbatenko, M.; Tretyakov, I.; Lobanov, Yu.; Maslennikov, S. N.; Kaurova, N.; Finkel, M.; Voronov, B.; Goltsman, G.; Klapwijk, T. M.
	Title	Nonequilibrium interpretation of DC properties of NbN superconducting hot electron bolometers			Type	Journal Article
	Year	2016	Publication	Appl. Phys. Lett.	Abbreviated Journal
	Volume	109	Issue	13	Pages	132602
	Keywords	HEB mixer, contacts
	Abstract	We present a physically consistent interpretation of the dc electrical properties of niobiumnitride (NbN)-based superconducting hot-electron bolometer mixers, using concepts of nonequilibrium superconductivity. Through this, we clarify what physical information can be extracted from the resistive transition and the dc current-voltage characteristics, measured at suitably chosen temperatures, and relevant for device characterization and optimization. We point out that the intrinsic spatial variation of the electronic properties of disordered superconductors, such as NbN, leads to a variation from device to device.
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	Notes				Approved	no
	Call Number				Serial	1107
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	Author	Semenov, A.; Richter, H.; Hübers, H.-W.; Petrenko, D.; Tretyakov, I.; Ryabchun, S.; Finkel, M.; Kaurova, N.; Gol’tsman, G.; Risacher, C.; Ricken, O.; Güsten, R.
	Title	Optimization of the intermediate frequency bandwidth in the THz HEB mixers			Type	Abstract
	Year	2014	Publication	Proc. 25^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 25^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	54
	Keywords	NbN HEB mixer
	Abstract	We report on the studies of the intermediate frequency (IF) bandwidth of quasi-optically coupled NbN hot-electron bolometer (HEB) mixers which are aimed at the optimization of the mixer performance at terahertz frequencies. Extension of the IF bandwidth due to the contribution of electron diffusion to the heat removal from NbN microbolometers has been already demonstrated for NbN HEBs at subterahertz frequencies. However, reducing the size of the microbolometer causes degradation of the noise temperature. Using in-situ multilayer manufacturing process we succeeded to improve the transparency of the contacts for electrons which go away from microbolometer to the metallic antenna. The improved transparency and hence coupling efficiency counterbalances the noise temperature degradation. HEB mixers were tested in a laboratory heterodyne receiver with a narrow-band cold filter which allowed us to eliminate direct detection. We used a local oscillator with a quantum cascade laser (QCL) at a frequency of 4.745 THz [1] which was developed for the H-Channel of the German Receiver for Astronomy at Terahertz frequencies (GREAT). Both the noise and gain bandwidth were measured in the IF range from 0.5 to 8 GHz using the hot-cold technique and preliminary calibrated IF analyzer with a tunable microwave filter. For optimized HEB geometry we found the noise bandwidth as large as 7 GHz. We compare our results with the conventional and the hot-spot mixer models and show that further extension of the IF bandwidth should be possible via improving the sharpness of the superconducting transition. The cross characterization of the HEB mixer was performed in the test bed of GREAT at the Max-Planck-Institut für Radioastronomie with the same QCL LO and delivered results which were consistent with the laboratory studies.
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	Call Number				Serial	1359
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	Author	Shcherbatenko, Michael; Lobanov, Yury; Benderov, Oleg; Shurakov, Alexander; Ignatov, Anton; Titova, Nadezhda; Finkel, Matvey; Maslennikov, Sergey; Kaurova, Natalya; Voronov, Boris M.; Rodin, Alexander; Klapwijk, Teunis M.; Gol'tsman, Gregory N.
	Title	Antenna-coupled 30 THz hot electron bolometer mixers			Type	Conference Article
	Year	2015	Publication	Proc. 26^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 26^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	27
	Keywords	HEB mixer, IR, mid-IR, 30 THz, antenna-coupled
	Abstract	We report on design and characterization of a superconducting Hot Electron Bolometer Mixer integrated with a logarithmic spiral antenna for mid-IR range observations. The antenna parameters have been adjusted to achieve the ultimate performance at 10 µm (30 THz) range where O3, NH3, CO2, CH4, N2O,…. lines in the Earth’s atmosphere, in planetary atmospheres and in the interstellar space can be observed. The HEB mixer is made of a thin NbN film deposited onto a GaAs substrate. To couple the radiation we rely on the quasioptical approach: the device is glued to a semi-spherical germanium lens with diameter~ 3 mm. A wet cryostat equipped with a germanium window and narrow band-pass filter is used to characterize the antenna and estimate the mixer performance.
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	Notes				Approved	no
	Call Number				Serial	1157
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	Author	Tretyakov, I.; Maslennikov, S.; Semenov, A.; Safir, O.; Finkel, M.; Ryabchun, S.; Kaurova, N.; Voronov, B.; Goltsman, G.; Klapwijk, T. M.
	Title	Impact of operating conditions on noise and gain bandwidth of NbN HEB mixers			Type	Conference Article
	Year	2015	Publication	Proc. 26^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 26^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	39
	Keywords	NbN HEB mixers
	Abstract	Hot-electron bolometer mixers (HEB’s) are the most promising devices as mixing element for terahertz spectroscopy and astronomy at frequencies beyond 1.4 THz. They have a low noise temperature and low demands on local oscillator (LO) power. 1,2 An important limitation is the IF bandwidth, of the order of a few GHz, and which in principle depends on energy relaxation due to electron- phonon processes and on diffusion-cooling. It has been proposed by Prober that a reduction in length of the HEB would lead to an increased bandwidth. 3 This appeared to be achieved by Tretyakov et al by measuring the gain bandwidth close to the critical temperature of the NbN. 2 Unfortunately, the noise bandwidth of similar devices operated at temperatures around 4.2 K appear not depend on the length. The fundamental problem to be addressed is the position-dependent superconducting state of the HEB- devices under operating conditions, which determines the conditions for the cooling of the hot quasiparticles. Some progress has been made by Barends et al in a semi-empirical model to describe the I,V curves under operating conditions at a bath temperature around 4.2 K. 4 In more recent work Vercruyssen et al have analyzed the I,V curve, without any LO-equivalent bias, of a model NSN system. 5 This work suggests that the most appropriate model for an HEB under operating conditions is that of a potential-well in the superconducting gap in the center of the NbN, analogous the bimodal superconducting state described by Vercruyssen et al. Hot quasiparticles in the well can not diffuse out and can only cool by electron-phonon processes, those with higher energies than the heights of the walls of the well can diffuse out. Using this working hypothesis we have carried out experiments on a sub-micrometer NbN bridge connected to a gold (Au) planar spiral antenna. An in situ process is used to deposit Au on NbN. The Au is removed in the center to define the uncovered NbN, which will act as the superconducting mixer itself. The antenna is deposited on the remaining Au layer on the NbN. The Au contacts suppress the energy gap of the NbN film located underneath the gold layer 7,8 . The measured resistive transition is shown in Fig.1. It clearly shows a T c of the bilayer at 6.2 K and the resistive transition of the NbN itself around 9 K. In addition we show the measured noise bandwidth (red squares) for different bath temperatures. Clearly the noise bandwidth increases strongly by increasing the bath temperature from 5 K to 8 K, up to 13 GHz. We interpret this pattern as evidence for improved out-diffusion of hot electrons due to normal banks and a shallow superconducting potential well compared to k B T. As expected the noise temperature in this regime is much bigger than when biased at 4.2 K. R EFERENCES 1 W. Zhang, P. Khosropanah, J. R. Gao, E. L. Kollberg, K. S. Yngvesson, T. Bansal, R. Barends, and T. M. Klapwijk Appl. Phys. Lett. 96, 111113, (2010). 2 Ivan Tretyakov, Sergey Ryabchun, Matvey Finkel, Anna Maslennikova, Natalia Kaurova, Anastasia Lobastova, Boris Voronov, and Gregory Gol’tsman Appl. Phys. Lett. 98, 033507 (2011). 3 D. E. Prober, Appl. Phys. Lett. 62, 2119 (1992). 4 R. Barends, M. Hajenius, J. R. Gao, and T. M. Klapwijk, Appl. Phys. Lett. 87, 263506 (2005). 5 N. Vercruyssen, T. G. A. Verhagen, M. G. Flokstra, J. P. Pekola, and T. M. Klapwijk Physical Review B 85, 224503 (2012).
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	Notes				Approved	no
	Call Number				Serial	1159
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	Author	Seliverstov, Sergey V.; Rusova, Anastasia A.; Kaurova, Natalya S.; Voronov, Boris M.; Goltsman, Gregory N.
	Title	AC-biased superconducting NbN hot-electron bolometer for frequency-domain multiplexing			Type	Conference Article
	Year	2017	Publication	Proc. 28^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 28^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	120-122
	Keywords	NbN HEB mixer
	Abstract	We present the results of characterization of fast and sensitive superconducting antenna-coupled THz direct detector based on NbN hot-electron bolometer (HEB) with AC-bias. We discuss the possibility of implementation of the AC-bias for design the readout system from the multi-element arrays of HEBs using standard technique of frequency-domain multiplexing. We demonstrate experimentally that this approach does not lead to significant deterioration of the HEB sensitivity compared with the value obtained for the same detector with DC- bias. Results of a numerical calculations of the HEB responsivity at AC-bias are in a good agreement with the experiment.
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	Notes				Approved	no
	Call Number				Serial	1174
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	Author	Antipov, S.; Trifonov, A.; Krause, S.; Meledin, D.; Desmaris, V.; Belitsky, V.; Gol’tsman, G.
	Title	Gain bandwidth of NbN HEB mixers on GaN buffer layer operating at 2 THz local oscillator frequency			Type	Conference Article
	Year	2017	Publication	Proc. 28^th Int. Symp. Space Terahertz Technol.	Abbreviated Journal	Proc. 28^th Int. Symp. Space Terahertz Technol.
	Volume		Issue		Pages	147-148
	Keywords	NbN HEB mixers, GaN buffer-layer, IF bandwidth
	Abstract	In this paper, we present IF bandwidth measurement results of NbN HEB mixers, which are employing NbN thin films grown on a GaN buffer-layer. The HEB mixers were operated in the heterodyne regime at a bath temperature of approximately 4.5 K and with a local oscillator operating at a frequency of 2 THz. A quantum cascade laser served as the local oscillator and a reference synthesizer based on a BWO generator (130-160 GHz) and a semiconductor superlattice (SSL) frequency multiplier was used as a signal source. By changing the LO frequency it was possible to record the IF response or gain bandwidth of the HEB with a spectrum analyzer at the operation point, which yielded lowest noise temperature. The gain bandwidth that was recorded in the heterodyne regime at 2 THz amounts to approximately 5 GHz and coincides well with a measurement that has been performed at elevated bath temperatures and lower LO frequency of 140 GHz. These findings strongly support that by using a GaN buffer-layer the phonon escape time of NbN HEBs can be significantly lower as compared to e.g. Si substrate, thus, providing higher gain bandwidth.
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	Notes				Approved	no
	Call Number				Serial	1175
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