A Liquid-Helium-Cooled Absolute Reference Cold Load forLong-Wavelength Radiometric Calibration

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....

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Bibliographic Details
Main Authors: Bensadoun, M., Witebsky, C., Smoot, George F., De Amici,Giovanni, Kogut, A., Levin, S.
Language:unknown
Published: 2009
Subjects:
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CALIBRATION STANDARDS
CALIBRATION
DESIGN
HELIUM
PERFORMANCE
RADIOMETERS
CRYOGENIC FLUIDS
MICROWAVE RADIATION
South Pole
South pole
Online Access:http://www.osti.gov/servlets/purl/892912
https://www.osti.gov/biblio/892912
Description
Summary: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 {le} 50 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 {le} 4.4 l/hr. 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.

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