Cosmic microwave background polarimetry using correlation receivers with the PIQUE and CAPMAP experiments

The Princeton IQU Experiment ( PIQUE) and the Cosmic Anisotropy Polarization Mapper ( CAPMAP) are experiments designed to measure the polarization of the cosmic microwave background ( CMB) on sub- degree scales in an area within 1 degrees of the North Celestial Pole using heterodyne correlation polarimeters and off- axis telescopes located in central New Jersey. PIQUE produced the tightest limit on the CMB polarization prior to its detection by DASI, while CAPMAP has recently detected polarization at l similar to 1000. The experimental methods and instrumentation for these two projects are described in detail with emphasis on the particular challenges involved in measuring the tiny polarized component of the CMB.