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Title:
Observations at Millimeter Wavelengths of Small Angular Scale Isotropy in the Cosmic Background Radiation.
Authors:
Radford, Simon John Elliott
Affiliation:
AA(UNIVERSITY OF WASHINGTON.)
Publication:
Thesis (PH.D.)--UNIVERSITY OF WASHINGTON, 1986.Source: Dissertation Abstracts International, Volume: 47-12, Section: B, page: 4919.
Publication Date:
00/1986
Category:
Physics: Astronomy and Astrophysics
Origin:
UMI
Bibliographic Code:
1986PhDT........20R

Abstract

The observed fine scale isotropy of the cosmic background radiation (CBR) is a strong constraint on theories of the genesis and evolution of large scale structure in the universe. This dissertation reports an experiment to determine the amplitude of CBR anisotropies. Observations at a wavelength of 2.2 mm were made with a far infrared photometer based on a composite semiconductor bolometer cooled to 0.35 K by evaporation of ('3)He. The photometer was operated in conjunction with a 9 m Cassegrain telescope located at an altitude of 1 km at the Battelle Observatory near Richland, WA. The FWHM beamwidth was 4', and nutation of the secondary mirror was used to switch the beam over an effective angular scale of 8'. Although millimeter wavelengths offer several advantages for these observations, previous ground based studies at these wavelengths have been limited by noise due to fluctuations in atmospheric emission and opacity. For this experiment, a sampling technique was developed that substantially reduces the effect of atmospheric noise. Using this technique, these measurements were limited by the intrinsic noise of the detector. The result of five nights' observations in March and April, 1986, is an upper limit to CBR anisotropies of (DELTA)T/T(,CBR) < 1.2 x 10('-4) at the 95% confidence level. In addition to demonstrating the performance of the apparatus and the efficacy of the sampling technique, this result is sufficient to constrain some currently popular cosmological models, excluding a baryon dominated universe, for example.
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