First Measurements of the Polarization of the Cosmic Microwave Background Radiation at Small Angular Scales from CAPMAP

Polarization results from the Cosmic Anisotropy Polarization MAPper (CAPMAP) experiment are reported. These are based on 433 hr, after cuts, observing a 2 deg2 patch around the north celestial pole with four 90 GHz correlation polarimeters coupled to optics defining 4' beams. The E-mode flat band-power anisotropy within l = 940 is measured as 66 μK2; the 95% confidence level upper limit for B-mode power within l = 1050 is measured as 38 μK2.