Measurement of the intensity of the cosmic background radiation at 3. 0 cm

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5472935

Friedman, S D

The intensity of the cosmic background radiation (CBR) was measured at a wavelength of 3.0 cm as part of a program to measure the Rayleigh-Jeans spectrum of the CBR at five wavelengths between 0.33 cm and 12 cm. The instrument used is a dual-antenna Dicke-switched radiometer with a double-sideband noise temperature of 490 K and a sensitivity of 46 mK/Hz/sup 1/2/. The entire radiometer is mounted on bearings. The atmospheric emission was measured by rotating the radiometer, and thus directing one antenna to zenith angles of +/-30 and +/-40/sup 0/. The CBR temperature is found by direct comparison with a liquid-helium-cooled absolute-reference load. This load consists of a large cylindrical waveguide, 70 cm in diameter and 130 cm long, terminated by a microwave absorder immersed in LHe. Only two thin polyethylene windows are between the antenna and the LHe. The load has extremely low loss at all five wavelengths of observation. At 3.0 cm reflected power and insertion loss from the walls and windows contribute an additional 20 +/- 10 mK to the antenna temperature of the LHe.

• Research Organization: California Univ., Berkeley (USA)
• OSTI ID: 5472935
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BACKGROUND RADIATION
COSMIC RADIATION
ELECTROMAGNETIC RADIATION
FLUX DENSITY
IONIZING RADIATIONS
MEASURING INSTRUMENTS
MEASURING METHODS
MICROWAVE RADIATION
RADIATION DETECTORS
RADIATIONS
RADIOMETERS