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Author Blundell, R.; Kawamura, J. H.; Tong, C. E.; Papa, D. C.; Hunter, T. R.; Gol’tsman, G. N.; Cherednichenko, S. I.; Voronov, B. M.; Gershenzon, E. M. url  doi
isbn  openurl
  Title A hot-electron bolometer mixer receiver for the 680-830 GHz frequency range Type Conference Article
  Year 1998 Publication Proc. 6-th Int. Conf. Terahertz Electron. Abbreviated Journal Proc. 6-th Int. Conf. Terahertz Electron.  
  Volume Issue Pages (down) 18-20  
  Keywords NbN HEB mixers  
  Abstract We describe a heterodyne receiver designed to operate in the partially transparent atmospheric windows centered on 680 and 830 GHz. The receiver incorporates a niobium nitride thin film, cooled to 4.2 K, as the phonon-cooled hot-electron mixer element. The double sideband receiver noise, measured over the frequency range 680-830 GHz, is typically 700-1300 K. The instantaneous output bandwidth of the receiver is 600 MHz. This receiver has recently been used at the SubMillimeter Telescope, jointly operated by the Steward Observatory and the Max Planck Institute for Radioastronomy, for observations of the neutral carbon and CO spectral lines at 810 GHz and at 806 and 691 GHz respectively. Laboratory measurements on a second mixer in the same test receiver have yielded extended high frequency performance to 1 THz.  
  Address Leeds, UK  
  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 0-7803-4903-2 Medium  
  Area Expedition Conference IEEE Sixth International Conference on Terahertz Electronics Proceedings. THZ 98. (Cat. No.98EX171)  
  Notes Approved no  
  Call Number Serial 1581  
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Author Baselmans, J. J. A.; Hajenius, M.; Gao, J. R.; Baryshev, A.; Kooi, J.; Klapwijk, T. M.; de Korte, P. A. J.; Voronov, B.; Gol’tsman, G. url  openurl
  Title Hot electron bolometer mixers with improved interfaces: sensitivity, LO power and stability Type Conference Article
  Year 2004 Publication Proc. 15th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 15th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages (down) 17-24  
  Keywords NbN HEB mixers  
  Abstract We study twin slot antenna coupled NbN hot electron bolometer mixers with an improved contact structure and a small volume, ranging from 1 µm × 0.1 µm to 2 × 0.3 µm. We obtain a DSB receiver noise temperature of 900 K at 1.6 THz and 940 K at 1.9 THz. To explore the practical usability of such small HEB mixers we evaluate the LO power requirement, the sensitivity and the stability. We find that the LO power requirement of the smallest mixers is reduced to about 240 nW at the Si lens of the mixer. This value is larger than expected from the isothermal technique and the known losses in the lens by a factor of 3-3.5. The stability of these receivers is characterized using a measurement of the Allan Variance. We find an Allan time of 0.5 sec. in an 80 MHz bandwidth. A small increase in stability can be reached by using a higher bias at the expense of a significant amount of sensitivity. The stability is sufficient for spectroscopic applications in a 1 MHz bandwidth at a 1 Hz chopping frequency.  
  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 1491  
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Author Cherednichenko, S.; Khosropanah, P.; Berg, T.; Merkel, H.; Kollberg, E.; Drakinskiy, V.; Voronov, B.; Gol’tsman, G. url  openurl
  Title Optimization of HEB mixer for the Herschel Space Observatory Type Abstract
  Year 2004 Publication Proc. 15th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 15th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages (down) 16  
  Keywords NbN HEB mixers, applications  
  Abstract A mixer development for the HIFI instrument of the Herschel Space Observatory has come to the final stage. In our paper and conference presentation we will describe the most important details of the Band 6 Low and High Mixer Unit design. Special attention will be given to the optimization of the hot- electron bolometer mixer chip, which is based on 3.5nm NbN superconducting film on silicon. As the HEB’s local oscillator power requirements depend on the bolometer size, we have compared mixer noise temperature for different bolometer width- to- length ratio. A trade- off between mixer performance and local oscillator power requirements results in the mixer units equipped with optimized mixer chips, providing the largest coverage of the Band6 RF band with the lowest possible receiver noise. A short account of the beam pattern measurements of Band6 mixers will be given as well.  
  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 1490  
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Author Ryabchun, Sergey; Tong, Cheuk-Yu Edward; Blundell, Raymond; Gol'tsman, Gregory url  doi
openurl 
  Title Stabilization scheme for hot-electron bolometer receivers using microwave radiation Type Journal Article
  Year 2009 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 19 Issue 1 Pages (down) 14-19  
  Keywords HEB, mixer, Allan variance, stabilization, radiometer equation  
  Abstract We present the results of a stabilization scheme for terahertz receivers based on NbN hot-electron bolometer (HEB) mixers that uses microwave radiation with a frequency much lower than the gap frequency of NbN to compensate for mixer current fluctuations. A feedback control loop, which actively controls the power level of the injected microwave radiation, has successfully been implemented to stabilize the operating point of the HEB mixer. This allows us to increase the receiver Allan time to 10 s and also improve the temperature resolution of the receiver by about 30% in the total power mode of operation.  
  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 1051-8223 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number RPLAB @ lobanovyury @ Serial 559  
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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. doi  openurl
  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 (down) 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 ν2 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  
  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 1099  
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Author Gao, J. R.; Hajenius, M.; Baselmans, J. J. A.; Klapwijk, T. M.; de Korte, P. A. J.; Voronov, B.; Gol'tsman, G. url  openurl
  Title NbN hot electron bolometer mixers with superior performance for space applications Type Conference Article
  Year 2004 Publication Proc. Int. workshop on low temp. electronics Abbreviated Journal Proc. Int. workshop on low temp. electronics  
  Volume Issue Pages (down) 11-17  
  Keywords NbN HEB mixers, applications  
  Abstract  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Noordwijk Editor Armandillo, E.; Leone, B.  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference International workshop on low temperature electronics- WOLTE 6 - Noordwijk  
  Notes Approved no  
  Call Number Serial 1496  
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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. url  openurl
  Title Noise performance of NbN hot electron bolometer mixers at 2.5 THz and its dependence on the contact resistance Type Conference Article
  Year 2003 Publication Proc. 14th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 14th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages (down) 11-19  
  Keywords NbN HEB mixers  
  Abstract NbN hot electron bolometer mixers (HEBM) are at this moment the best heterodyne receivers for frequencies above 1 Thz. However, the fabrication procedure of these devices is such that the quality of the interface between the NbN superconducting film and the contact structure is not under good control. The result is a low transparency interface between the bolometer itself and the contact/antenna structure. In this paper we report a detailed experimental study on a novel idea to increase the transparency of this interface. This leads to a record sensitivity and more reproducible performance. We compare identical bolometers, coupled with a spiral antenna, with different NbN bolometer-contact pad interfaces. We find that cleaning the NbN interface alone results in an increase in the noise temperature. However, cleaning the NbN interface and adding a thin additional superconductor prior to the gold contact deposition improves the noise temperature of the HEBm with more than a factor of 2. A device with a contact pad on top of an in-situ cleaned NbN film consisting of 10 nm of NbTiN and 40 nm of gold has a DSB noise temperature of 1050 K 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 1497  
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Author Zorin, M.; Lindgren, M.; Danerud, M.; Karasik, B.; Winkler, D.; Gol'tsman, G.; Gershenzon, E. url  doi
openurl 
  Title Nonequilibrium and bolometric responses of YBaCuO thin films to high-frequency modulated laser radiation Type Journal Article
  Year 1995 Publication J. Supercond. Abbreviated Journal J. Supercond.  
  Volume 8 Issue 1 Pages (down) 11-15  
  Keywords YBCO HTS HEB  
  Abstract Picosecond nonequilibrium and slow bolometric responses to infrared radiation from a patterned high-T c superconducting (HTS) film in resistive and normal states deposited onto LaAlO3, NdGaO3, and MgO substrates were investigated using both pulse and modulation techniques. The response time of 35 ps to a laser pulse of 17 ps FWHM has been observed. The intrinsic response time of the fast process is expected to be about a few picoseconds. The modulation technique, being free from the disadvantages of pulse methods (poor sensitivity, limited dynamic range), makes the detailed study of a number of relaxation processes possible. Besides the nonequilibrium response, two kinds of bolometric processes, namely phonon transport through the film-substrate interface and phonon thermal diffusion in a substrate, manifest themselves in certain frequency dependences.  
  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 0896-1107 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1630  
Permanent link to this record
 

 
Author Gershenzon, E. M.; Gershenson, M. E.; Goltsman, G. N.; Lyulkin, A. M.; Semenov, A. D.; Sergeev, A. V. url  openurl
  Title Limiting characteristics of fast-response superconducting bolometers Type Journal Article
  Year 1989 Publication Zhurnal Tekhnicheskoi Fiziki Abbreviated Journal Zhurnal Tekhnicheskoi Fiziki  
  Volume 59 Issue 2 Pages (down) 11-120  
  Keywords HEB  
  Abstract Теоретически и экспериментально исследовано физическое ограничение быстродействия сверхпроводящего болометра. Показано, что минимальная постоянная времени реализуется в условиях электронного разогрева и определяется процессом неупругого электрон-фонон-ного взаимодействия. Сформулированы требования к конструкции «электронного болометра» для достижения предельной чувствительности. Проведено сравнение характеристик электрон­ного болометра и обычных болометров различных типов.  
  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 1696  
Permanent link to this record
 

 
Author Yang, Z. Q.; Hajenius, M.; Baselmans, J. J. A.; Gao, J. R.; Voronov, B.; Gol’tsman, G. N. url  doi
openurl 
  Title Reduced noise in NbN hot-electron bolometer mixers by annealing Type Journal Article
  Year 2006 Publication Supercond. Sci. Technol. Abbreviated Journal Supercond. Sci. Technol.  
  Volume 19 Issue 4 Pages (down) L (9 to 12)  
  Keywords NbN HEB mixers  
  Abstract We find that the sensitivity of heterodyne receivers based on superconducting hot-electron bolometers (HEBs) increases by 25–30% after annealing at 85 °C in vacuum. The devices studied are twin-slot antenna coupled mixers with a small NbN bridge of 1 × 0.15 µm2. We show that annealing changes the device properties as reflected in sharper resistive transitions of the complete device, apparently reducing the device-related noise. The lowest receiver noise temperature of 700 K is measured at a local oscillator frequency of 1.63 THz and a bath temperature of 4.3 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 0953-2048 ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1456  
Permanent link to this record
 

 
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. doi  openurl
  Title A HIFI preview of warm molecular gas around χ 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 (down) L6  
  Keywords HEB mixer applications, HIFI, Herschel, stars: AGB and post-AGB / circumstellar matter / stars: kinematics and dynamics / stars: individual: χ 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 χ 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 χ 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.
 
  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 1096  
Permanent link to this record
 

 
Author Trifonov, A.; Tong, C.-Y. E.; Grimes, P.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. doi  openurl
  Title Development of A Silicon Membrane-based Multi-pixel Hot Electron Bolometer Receiver Type Conference Article
  Year 2017 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 27 Issue 4 Pages (down) 6  
  Keywords Multi-pixel, HEB, silicon-on-insulator, horn array  
  Abstract We report on the development of a multi-pixel

Hot Electron Bolometer (HEB) receiver fabricated using

silicon membrane technology. The receiver comprises a

2 × 2 array of four HEB mixers, fabricated on a single

chip. The HEB mixer chip is based on a superconducting

NbN thin film deposited on top of the silicon-on-insulator

(SOI) substrate. The thicknesses of the device layer and

handling layer of the SOI substrate are 20 μm and 300 μm

respectively. The thickness of the device layer is chosen

such that it corresponds to a quarter-wave in silicon at

1.35 THz. The HEB mixer is integrated with a bow-tie

antenna structure, in turn designed for coupling to a

circular waveguide,
 
  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 @ kovalyuk @ Serial 1111  
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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. doi  openurl
  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 (down) 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.  
  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 1090  
Permanent link to this record
 

 
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. doi  openurl
  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 (down) 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.
 
  Address  
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  Series Editor Series Title Abbreviated Series Title  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1084  
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Author Hübers, H.-W.; Semenov, A.; Richter, H.; Birk, M.; Krocka, M.; Mair, U.; Smirnov, K.; Gol’tsman, G.; Voronov, B. url  openurl
  Title Terahertz Heterodyn Receiver with a hot-electron bolometer mixer Type Conference Article
  Year 2002 Publication Far-IR, Sub-mm & MM Detector Technology Workshop Abbreviated Journal Far-IR, Sub-mm & MM Detector Technology Workshop  
  Volume Issue Pages (down) 3-24  
  Keywords NbN HEB mixers  
  Abstract During the past decade major advances have been made regarding low noise mixers for terahertz (THz) heterodyne receivers. State of the art hot-electron-bolometer (HEB) mixers have noise temperatures close to the quantum limit and require less than a µW power from the local oscillator (LO). The technology is now at a point where the performance of a practical receiver employing such mixer, rather than the figures of merit of the mixer itself, are of major concern. We have incorporated a phonon-cooled NbN HEB mixer in a 2.5 THz heterodyne receiver and investigated the performance of the receiver. This yields important information for the development of heterodyne receivers such as GREAT (German receiver for astronomy at THz frequencies aboard SOFIA) [1] and TELIS (Terahertz limb sounder), a balloon borne heterodyne receiver for atmospheric research [2]. Both are currently under development at DLR.  
  Address  
  Corporate Author Thesis  
  Publisher NASA Place of Publication Editor Wolf, U.; Farhoomand, J.; McCreight, C.R.  
  Language Summary Language Original Title  
  Series Editor Series Title NASA CP Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Volume: 211408 Approved no  
  Call Number Serial 1537  
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