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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 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 | 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. |
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| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1096 | |||
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| Author | Karasik, B. S.; Elantiev, A. I. | ||||
| Title | Noise temperature limit of a superconducting hot-electron bolometer mixer | Type | Journal Article | ||
| Year | 1996 | Publication | Applied Physics Letters | Abbreviated Journal | Appl. Phys. Lett. |
| Volume | 68 | Issue | 6 | Pages | 853-855 |
| Keywords | HEB mixer noise temperature, Johnson noise, thermal fluctuation noise, noise bandwidth | ||||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 0003-6951 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 260 | |||
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| Author | Karasik, B. S.; Il'in, K. S.; Pechen, E. V.; Krasnosvobodtsev, S. I. | ||||
| Title | Diffusion cooling mechanism in a hot-electron NbC microbolometer mixer | Type | Journal Article | ||
| Year | 1996 | Publication | Applied Physics Letters | Abbreviated Journal | Appl. Phys. Lett. |
| Volume | 68 | Issue | 16 | Pages | 2285-2287 |
| Keywords | HEB mixer, diffusion cooling channel, diffusion channel | ||||
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| ISSN | 0003-6951 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 262 | |||
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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. 6th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 6th 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. | ||||
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| Publisher | Place of Publication | Pasadena, Ca | Editor | ||
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| Notes | Approved | no | |||
| Call Number | Serial | 258 | |||
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| Author | Karasik, B. S.; Gol'tsman, G. N.; Voronov, B. M.; Svechnikov, S. I.; Gershenzon, E. M.; Ekstrom, H.; Jacobsson, S.; Kollberg, E.; Yngvesson, K. S. | ||||
| Title | Hot electron quasioptical NbN superconducting mixer | Type | Journal Article | ||
| Year | 1995 | Publication | IEEE Trans. Appl. Supercond. | Abbreviated Journal | IEEE Trans. Appl. Supercond. |
| Volume | 5 | Issue | 2 | Pages | 2232-2235 |
| Keywords | NbN HEB mixers | ||||
| Abstract | Hot electron superconductor mixer devices made of thin NbN films on SiO/sub 2/-Si/sub 3/N/sub 4/-Si membrane have been fabricated for 300-350 GHz operation. The device consists of 5-10 parallel strips each 5 /spl mu/m long by 1 /spl mu/m wide which are coupled to a tapered slot-line antenna. The I-V characteristics and position of optimum bias point were studied in the temperature range 4.5-8 K. The performance of the mixer at higher temperatures is closer to that predicted by theory for uniform electron heating. The intermediate frequency bandwidth versus bias has also been investigated. At the operating temperature 4.2 K a bandwidth as wide as 0.8 GHz has been measured for a mixer made of 6 nm thick film. The bandwidth tends to increase with operating temperature. The performance of the NbN mixer is expected to be better for higher frequencies where the absorption of radiation should be more uniform. | ||||
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| Series Volume | Series Issue | Edition | |||
| ISSN | 1051-8223 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1622 | |||
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| Author | Karasik, B.S.; Lindgren, M.; Zorin, M.A.; Danerud, M.; Winkler, D.; Trifonov, V.V.; Gol’tsman, G.N.; Gershenzon, E.M. | ||||
| Title | Picosecond detection and broadband mixing of near-infrared radiation by YBaCuO films | Type | Conference Article | ||
| Year | 1994 | Publication | Proc. SPIE | Abbreviated Journal | Proc. SPIE |
| Volume | 2159 | Issue | Pages | 68-76 | |
| Keywords | YBCO HTS HEB mixer | ||||
| Abstract | Nonequilibrium picosecond and bolometric responses of YBCO films 500 angstroms thick patterned into 20 X 20 micrometers 2 size structure to 17 ps laser pulses and modulated radiation of GaAs and CO2 lasers have been studied. The modulation frequencies up to 10 GHz for GaAs laser and up to 1 GHz for CO2 were attained. The use of small radiation power (1 – 10 mW/cm2 for cw radiation and 10 – 100 nJ/cm2 for pulse radiation) in combination with high sensitive read-out system made possible to avoid any non-linear transient processes caused by an overheating of sample above a critical temperature or S-N switching enhanced by an intense radiation. Responses due to the change of kinetic inductance were believed to be negligible. The only signals observed were caused by a small change of the film resistance either in the resistive state created by a bias current or in the normal state. The data obtained by means of pulse and modulation techniques are in agreement. The responsivity about 1 V/W was measured at 1 GHz modulation frequency both for 0.85 micrometers and 10.6 micrometers wavelengths. The sensitivity of high-Tc fast wideband infrared detector is discussed. | ||||
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| Publisher | Spie | Place of Publication | Editor | Nahum, M.; Villegier, J.-C. | |
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| Area | Expedition | Conference | High-Temperature Superconducting Detectors: Bolometric and Nonbolometric | ||
| Notes | Approved | no | |||
| Call Number | Serial | 1640 | |||
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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 YBa2Cu3O7-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 | ||||
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| Address | Moscow-Zvenigorod | ||||
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| Publisher | Place of Publication | Moscow-Zvenigorod | Editor | ||
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| Notes | Approved | no | |||
| Call Number | Serial | 355 | |||
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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. 8th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 8th 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. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 275 | |||
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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. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 322 | |||
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| Author | Kawamura, J.; Blundell, R.; Tong, C.-Y. E.; Gol'tsman, G.; Gershenzon, E.; Voronov, B. | ||||
| Title | NbN hot-electron mixer measurements at 200 GHz | Type | Conference Article | ||
| Year | 1995 | Publication | Proc. 6th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 6th Int. Symp. Space Terahertz Technol. |
| Volume | Issue | Pages | 254-261 | ||
| Keywords | NbN HEB mixers | ||||
| Abstract | We present noise and gain measurements of resistively driven NbN hot-electron mixers near 200 GHz. The device geometry is chosen so that the dominant cooling process of the hot-electrons is their interaction with the lattice. Except for a single batch, the intermediate frequency cut-off of these mixer elements is – 3 700 MHz, and has shown little variation among other batches of devices. At 100 MHz we measured intrinsic mixer losses as low as —3 dB. We measured the noise temperatures at several intermediate frequencies, and for the best de- vice at 137 MHz with 20 MHz bandwidth, we measured 2000 K; using a low-noise first- stage amplifier at 1.5 GHz with 200 MHz bandwidth, the receiver noise temperature measured 2800 K. We estimate that the noise contribution from the mixer is 500 K and the total losses are —15 dB at 137 MHz. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 1626 | |||
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