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Session 52 - Source Surveys and CMB Radiation.
Display session, Wednesday, June 10
Atlas Ballroom,
The development of low-noise, broadband millimeter-wave amplifiers has made interferometry the technique of choice for precision ground-based measurement of the cosmic microwave background (CMB). The Degree Angular Scale Interferometer (DASI) is an instrument designed to image the CMB over large regions of the sky. Its 13 element array is configured to optimize sensitivity to the CMB angular power spectrum from \ell = 160 to \ell = 710, with single-field resolution of \Delta \ell \approx 30. Each array element consists of a 20-cm diameter lensed corrugated horn and a cryogenic HEMT amplifier-based 26 - 36 GHz receiver. All 13 elements, along with the 10 \times 1 GHz bandwidth complex correlator, are mounted to a single 1.6m diameter aperture plate, which is steerable by the telescope about three axes: azimuth, elevation, and the boresight axis. This compact design eliminates the need for delay lines, provides flexibility in sky and u,v coverage, and increases control over instrument systematics. It also will permit efficient installation of the instrument at its observing site, the South Pole, where excellent atmospheric transparency and stability offer ideal conditions for large-field interferometry. Construction of the telescope will be completed in Summer 1998, and DASI will be deployed at the South Pole for year-round operation starting in November 1999.
