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Special Cosmology Seminar
Design and Deployment of the first Multichroic Polarimeter array on the Atacama Cosmology Telescope
Date: Thursday, February 4th
Time: 3:30 pm
Place: 5280 Chamberlin Hall
Speaker: Rahul Datta, University of Michigan
Abstract: The polarization of the Cosmic Microwave Background (CMB) provides a unique window into the physics of inflation, an alternative means to measure the neutrino mass sum, and enables a multitude of other astrophysical studies. Measurements of the inflationary B-mode signal requires instruments capable of mapping the CMB at multiple frequency bands with unprecedented sensitivity and excellent control over systematics. Feedhorn-coupled detectors with sensitivity to multiple spectral bands within a single focal plane element offer an avenue to achieve these goals. The Atacama Cosmology Telescope Polarimeter (ACTPol) instrument is optimized to make arcminute resolution measurements of CMB polarization, CMB lensing, and other secondary anisotropies. I will present the design of a feedhorn-coupled multichroic detector array encompassing the 90 and 150 GHz frequency bands and the ancillary technology needed to implement this array in the ACTPol experiment. This receiver, deployed in January 2015, represents the first multichroic detector array deployed for a CMB experiment and is now the most sensitive ACTPol array. I will also present the preliminary on-sky performance of this array. I shall conclude with a brief discussion about the ongoing work on the detection of polarized point sources in the ACTPol CMB maps and their impact on the estimation of the E-mode polarization power spectrum.
Host: Kam Arnold
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