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TopHat in Antarctica

The second phase of the Medium-Scale Anisotropy Measurement (MSAM2) uses an adiabatic demagnetization refrigerator to cool a new radiometer to 0.1 K. This new instrument, equipped with 5 spectral bands between 2.3 and 5.67 icm (70 and 170 GHz, 1.76 and 4.3 mm), will provide a powerful observational check for foreground sources as well as provide at least a factor of 3 improvement over MSAM1 sensitivity to CMBR anisotropy. The increased sensitivity and smaller beam size (20' FWHM) will allow us to constrain cosmological models and parameters by measuring the CMBR correlation function out to the 2nd acoustic (Doppler) peak - the predicted characteristics of this peak are highly model dependent.