R ACBAR : The Arcminute Cosmology Bolometer Array Receiver

We describe the Arcminute Cosmology Bolometer Array Receiver (Acbar); a multifrequency millimeter-wave receiver designed for observations of the Cosmic Microwave Background (CMB) and the Sunyaev-Zel’dovich effect in clusters of galaxies. The Acbar focal plane consists of a 16-pixel, background-limited, 240 mK bolometer array that can be configured to observe simultaneously at 150, 220, 280, and 350 GHz. With 4 − 5 FWHM beams and a 3 azimuth chop, Acbar is sensitive to a wide range of angular scales. Acbar was installed on the 2 m Viper telescope at the South Pole in January 2001. We describe the design of the instrument and its performance during the 2001 and 2002 observing seasons. Subject headings: cosmic microwave background – instrumentation, observations Department of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 Current address: Enrico Fermi Institute, University of Chicago, LASR-132, Chicago, IL 60637: mcrunyan@grizelda.uchicago.edu Department of Physics and Astronomy, Cardiff University, CF24 3YB Wales, UK European Space Agency, 2200 AG Noordwijk, The Netherlands Jet Propulsion Laboratory, Pasadena, CA 91125 Department of Physics, University of California at Berkeley, Berkeley, CA 94720 Department of Physics, Case Western Reserve University, Cleveland, OH 44106 Department of Physics, University of California, Santa Barbara, CA 93106 Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720 Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213