UC w 6 Submitted to Review of Scientific Instruments A Liquid-Helium-Cooled Absolute Reference Cold Load for Long-Wavelength Radiometric Calibration e Not to be taken from this room A liquid helium-cooled absolute reference cold load for long-wavelength r

• Main Authors: M Bensadoun, C Witebsky, G Smoot, G De Amici, A Kogut, S Levin, Marc Bensadoun, Chris Witebsky, George Smoot, Giovanni De Amici, A I Kogut, Steve Levin
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: South Pole; South pole
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1070.2769

ABSTRACT We describe a large (78-cm) diameter liquid-helium-cooled black-body absolute reference cold load for the calibration of microwave radiometers. The load provides an absolute calibration near the liquid helium (LHe) boiling point, accurate to better than 30 mK for wavelengths from 2.5 to 25 cm (12-1.2 GHz). The emission (from non-LHe temperature parts of the cold load) and reflection are small and well determined. Total corrections to the LHe boiling point temperature are 150 mK over the operating range. This cold load has been used at several wavelengths at the South Pole and at the White Mountain Research Station. In operation, the average LHe loss rate was 24.4 Vhr. Design considerations, radiometric and thermal performance and operational aspects are discussed. A comparison with other LHe-cooled reference loads including the predecessor of this cold load is given.