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 upon 433 hours, after cuts, observing a 2 square degree patch around the North Celestial Pole (NCP) with four 90 GHz correlation polarimeters coupled to optics defining $4\text{arcmin}$ beams. The E-mode flat bandpower anisotropy within $\mathrm{\ell }=940_{-300}^{+330}$ is measured as 66${}_{-29}^{+69}\mu$K${}^2$; the 95% Confidence level upper limit for B-mode power within $\mathrm{\ell }=1050_{-520}^{+590}$ is measured as 38 $\mu$K${}^2$.