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Author (up) Pentin, Ivan; Finkel, Matvey; Maslennikov, Sergey; Vakhtomin, Yuri; Smirnov, Konstantin; Kaurova, Nataliya; Goltsman, Gregory url  openurl
  Title Superconducting hot-electron-bolometer mixers for the mid-IR Type Journal Article
  Year 2017 Publication Rus. J. Radio Electron. Abbreviated Journal Rus. J. Radio Electron.  
  Volume Issue 10 Pages  
  Keywords IR NbN HEB mixers  
  Abstract The work presents the result of development of the NbN superconducting hot-electron-bolometer (HEB) mixer. The sensitive element of the mixer is directly coupled to mid-IR radiation, and doesn’t have planar metallic antenna. Investigations of noise characteristics of NbN HEB mixer were performed at the frequency 28.4 THz (λ = 10.6 µm) by using gas-discharge CW CO2-laser without consideration of optical and electrical losses in the heterodyne receiver. The noise temperature of NbN HEB mixer with the size of the sensitive element 10 µm × 10 µm was 2320 K (~ 1.5hν/kB) at the heterodyne frequency of 28.4 THz. The noise temperature was determined by measuring the Y-factor taking into account the term which describes fluctuations of zero-point oscillations in accordance with the fluctuation-dissipation theorem of Calle-Welton. Isothermal method was used to estimate the absorbed heterodyne radiation power which was 9 µW at the optimal operating point for the minimum noise temperature of NbN HEB mixer.  
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  Language Russian Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1684-1719 ISBN Medium  
  Area Expedition Conference  
  Notes http://jre.cplire.ru/jre/oct17/9/abstract.html (Russian) Гетеродинный приемник со сверхпроводниковым смесителем на эффекте электронного разогрева для среднего инфракрасного диапазона Approved no  
  Call Number Serial 1747  
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Author (up) Phillips, T. G.; Jefferts, K. B. doi  openurl
  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.  
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  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 927  
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Author (up) Pineda, J. L.; Langer, W. D.; Velusamy, T.; Goldsmith, P. F. doi  openurl
  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 χ0 â‰<192> 1 – 30.
 
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  Notes Approved no  
  Call Number Serial 1100  
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Author (up) Pineda, J. L.; Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Li, D.; Yorke, H. W. doi  openurl
  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 (χ0 = 1–10). We find two regions where our analysis suggest high densities >105 cm-3 and strong FUV fields (χ0 = 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.  
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  Notes Approved no  
  Call Number Serial 1101  
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Author (up) Prober, D. E. openurl 
  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  
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  Area Expedition Conference  
  Notes Recommended by Klapwijk Approved no  
  Call Number Serial 244  
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