Measurements of anisotropies in the Cosmic Microwave Background at small and intermediate angular scales with bolometric receivers at mm wavelengths

This thesis describes instruments and observational techniques used to make precise measurements of anisotropies in the Cosmic Microwave Background (CMB) at mm wavelengths. New developments in bolometer design and fabrication for millimeter-wave receivers are presented. Additional developments in cryogenics, readout electronics and mm-wave filters enable the construction of mm-wave receivers that take full advantage of these improvements in bolometer sensitivity. The design and performance of two millimeter-wave receivers for measuring CMB anisotropies at angular scales from a few arcminutes to ten degrees is presented. The first multifrequency array receiver for millimeter-wave astronomy, SuZIE I.5, is described. SuZIE I.5 is the second generation receiver built for the Sunyaev-Zel'dovich Infrared Experiment (SuZIE). The interaction of the CMB with hot plasma bound in clusters of galaxies, the Sunyaev-Zel'dovich (S-Z) effect, is the dominant source of CMB anisotropies at arcminute scales. Measurement of the spectrum of the Sunyaev-Zel'dovich effect at millimeter wavelengths enables the separation of contributions from the bulk motion of the cluster with respect to the rest frame of the Cosmic Microwave Background (CMB) and the random thermal motion of the electrons in the hot intracluster gas. SuZIE I.5 was used to make measurements of the spectrum of S-Z effect in the cluster, Abell 1835 (z=0.2523). These measurements are combined with the results of X-ray data in order to determine the Hubble constant (H0) and the radial component of cluster peculiar velocity (vr). The second receiver described is the BOOMERANG instrument, a bolometric radiometer designed to map the Cosmic Background Radiation (CMB) with 0.2o resolution over a large portion of the sky. This receiver will employ new technologies in bolometers, readout electronics, cold reimaging optics, millimeter-wave filters, and cryogenics to obtain unprecedented sensitivity to CMB anisotropies combined with long integration time from a Long Duration Balloon (LDB) platform.* (Abstract shortened by UMI.) ftn*Originally published in DAI vol. 58, no. 7. Reprinted here with corrected title