Dr. Anthony Readhead and colleagues at the California Institute of Technology will continue to use the Cosmic Background Imager (CBI) to make observations of the Cosmic Microwave Background Radiation (CMBR) on angular scales of 3 arc minutes to 0.5 degrees. The CBI is located in the Chilean Andes at an altitude of 5000 meters. The prime objective of the CBI project is to measure the angular power spectrum of the CMBR over the multipole moment range l=400 to 3000. An additional program will be carried out to measure secondary fluctuations in the CMBR caused by the scattering of the CMBR photons off the hot electrons in clusters of galaxies - the Sunyaev-Zel'dovich Effect. A complete sample of 19 nearby clusters will be observed with the CBI, and these observations will be combined with X-ray observations to determine the Hubble Constant with 10% accuracy. The team includes graduate students and post-doctoral fellows. This work addresses a fundamental area of science with a state-of-the-art instrument and is expected to make a significant contribution to our understanding of the origin and evolution of the Universe. ***
