15 July 2010 ALMA front-end verification using dry cold load
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Abstract
We describe the design and characterisation of a cryogenic millimetre/sub-millimetre wave calibration load, cooled by use of a closed cycle refrigerator that is used to test the performance of the ALMA receiver front-end system. Use of the refrigerator removes the need for liquid cryogen (nitrogen) cooling and allows for long duration, and unattended operation independent of orientation angle. Key requirements of the load include provision of a well-characterised and constant brightness temperature over a wide frequency range (from ~100 GHz to ~1 THz) polarisation insensitivity, high emissivity and mechanical stability. Test and verification of the load performance characteristics is achieved by using several measurement techniques; these are presented and compared with measurements made using a liquid cryogen load (cooled reference).
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Yoonjae Lee, Yoonjae Lee, Brian Ellison, Brian Ellison, Peter Huggard, Peter Huggard, Mark Harman, Mark Harman, Abdelhakim Boughriet, Abdelhakim Boughriet, Wojciech Bartynowski, Wojciech Bartynowski, Matthew Oldfield, Matthew Oldfield, Nigel Morris, Nigel Morris, Peter Hekman, Peter Hekman, Gie Han Tan, Gie Han Tan, } "ALMA front-end verification using dry cold load", Proc. SPIE 7741, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V, 77412K (15 July 2010); doi: 10.1117/12.857302; https://doi.org/10.1117/12.857302
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