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Author Billade, Bhushan; Belitsky, Victor; Pavolotsky, Alexey; Lapkin, Igor; Kooi, Jacob openurl 
  Title ALMA band 5 (163-211 GHz) sideband separation mixer Type Conference Article
  Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal  
  Volume Issue Pages 19-23  
  Keywords SIS mixer, noise temperature, ALMA, band 5  
  Abstract We present the design of ALMA Band 5 sideband separation SIS mixer and experimental results for the double side band mixer and first measurement results 2SB mixer. In this mixer, the LO injection circuitry is integrated on the mixer substrate using a directional coupler, combining microstrip lines with slot-line branches in the ground plane. The isolated port of the LO coupler is terminated by wideband floating elliptical termination. The mixer employs two SIS junctions with junction area of 3 µm² each, in the twin junction configuration, followed by a quarter wave transformer to match the RF probe. 2SB mixer uses two identical but mirrored chips, whereas each DSB mixer has the same end-piece configuration. The 2S mixer has modular design such that DSB mixers are measured independently and then integrated into 2SB simply by placing around the middle piece. Measurements of the DSB mixer show noise temperature of around 40K over the entire band. 2SB mixer is not fully characterized yet, however, preliminary measurement indicates SSB (un-corrected) noise temperature of 80K.  
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  Notes Approved no  
  Call Number (up) Serial 616  
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Author Li, Chao-Te; Chen, Tse-Jun; Ni, Tong-Liang; Lu, Wei-Chun; Chiu, Chuang-Ping; Chen, Chong-Wen; Chang, Yung-Chin; Wang, Ming-Jye Shi, Sheng-Cai openurl 
  Title Development of SIS mixers for SMA 400-520 GHz band Type Conference Article
  Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal  
  Volume Issue Pages 24-30  
  Keywords SIS mixer, noise temperature, SMA  
  Abstract SIS junction mixers were developed for SMA 400-520 GHz band. The results show receiver noise temperature around 100 K across the band, with noise contribution from RF loss and IF estimated to be around 50 K and 20K, respectively. Two schemes were used to tune out junction's parasitic capacitance. When a parallel inductor is employed, the input impedance is close to Rn, which facilitates impedance matching between the junction and the waveguide probe. Waveguide probes were designed to achieve a low feed-point impedance to match to the junction resistance. Optimum embedding impedances for lower receiver noise temperature were investigated. Performances of two schemes and composition of receiver noise were also discussed.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number (up) Serial 617  
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Author Jackson, B. D.; Hesper, R.; Adema, J.; Barkhof, J.; Baryshev, A. M.; Zijlstra, T.; Zhu, S.; Klapwijk, T. M. openurl 
  Title Series production of state-of-the-art 602-720 GHz SIS receivers for band 9 of ALMA Type Conference Article
  Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal  
  Volume Issue Pages 7-11  
  Keywords SIS mixer, noise temperature, ALMA, band 9  
  Abstract The Atacama Large Millimeter/Sub-millimeter Array (ALMA) requires the development and production of 73 state-of-the-art receivers for the 602-720 GHz range – the ALMA Band 9 cartridges. Development and pre-production of the first 8 cartridges was completed between 2003 and 2008, resulting in a cartridge design that meets the project's challenging requirements. The cartridge design remains essentially unchanged for production, while the production and test processes developed during pre-production have been fine-tuned to address the biggest new challenge for this phase – ramping up production to a rate of 2 cartridges per month over 2009-2012.  
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  Notes Approved no  
  Call Number (up) Serial 618  
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Author Risacher, C.; Meledin, D.; Belitsky, V.; Bergman, P. openurl 
  Title First 1.3 THz observations at the APEX telescope Type Conference Article
  Year 2009 Publication Proc. 20th 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.  
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  Notes Approved no  
  Call Number (up) Serial 619  
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Author Shah, Jagdeep; Pinczuk, A.; Gossard, A. C.; Wiegmann, W. openurl 
  Title Energy-loss rates for hot electrons and holes in GaAs quantum wells Type Journal Article
  Year 1985 Publication Phys. Rev. Lett. Abbreviated Journal Phys. Rev. Lett.  
  Volume 54 Issue Pages 2045-2048  
  Keywords 2DEG, GaAs/AlGaAs, heat flow, electron-phonon, hole-phonon, carrier-phonon, interactions  
  Abstract We report the first direct determination of carrier-energy-loss rates in a semiconductor. These measurements provide fundamental insight into carrier-phonon interactions in semiconductors. Unexpectedly large differences are found in the energy-loss rates for electrons and holes in GaAs/AlGaAs quantum wells. This large difference results from an anomalously low electron-energy-loss rate, which we attribute to the presence of nonequilibrium optical phonons rather than the effects of reduced dimensionality or dynamic screening.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number (up) Serial 633  
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