Long-timescale stability in CMB observations at multiple frequencies using front-end polarization modulation

Joseph Cleary; Rahul Datta; John W. Appel; Charles L. Bennet; David T. Chuss; Jullianna Denes Couto; Sumit Dahal; Francisco Espinoza; Thomas Essinger-Hileman; Kathleen Harrington; Jeffery Iuliano; Yunyang Li; Tobias A. Marriage; Carolina Núñez; Matthew A. Petroff; Rodrigo A. Reeves; Rui Shi; Duncan J. Watts; Edward J. Wollack; Zhilei Xu

doi:10.1117/12.2629723

31 August 2022 Long-timescale stability in CMB observations at multiple frequencies using front-end polarization modulation

Joseph Cleary, Rahul Datta, John W. Appel, Charles L. Bennet, David T. Chuss, Jullianna Denes Couto, Sumit Dahal, Francisco Espinoza, Thomas Essinger-Hileman, Kathleen Harrington, Jeffery Iuliano, Yunyang Li, Tobias A. Marriage, Carolina Núñez, Matthew A. Petroff, Rodrigo A. Reeves, Rui Shi, Duncan J. Watts, Edward J. Wollack, Zhilei Xu

Author Affiliations +

Proceedings Volume 12190, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI; 121902Q (2022) https://doi.org/10.1117/12.2629723
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

The Cosmology Large Angular Scale Surveyor (CLASS) is a telescope array observing the Cosmic Microwave Background (CMB) at frequency bands centered near 40, 90, 150, and 220 GHz. CLASS measures the CMB polarization on the largest angular scales to constrain the inflationary tensor-to-scalar ratio and the optical depth due to reionization. To achieve the long time-scale stability necessary for this measurement from the ground, CLASS utilizes a front-end, variable-delay polarization modulator on each telescope. Here we report on the improvements in stability afforded by front-end modulation using data across all four CLASS frequencies. Across one month of modulated linear polarization data in 2021, CLASS achieved median knee frequencies of 9.1, 29.1, 20.4, and 36.4 mHz for the 40, 90, 150, and 220 GHz observing bands. The knee frequencies are approximately an order of magnitude lower than achieved via CLASS pair-differencing orthogonal detector pairs without modulation.

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Joseph Cleary, Rahul Datta, John W. Appel, Charles L. Bennet, David T. Chuss, Jullianna Denes Couto, Sumit Dahal, Francisco Espinoza, Thomas Essinger-Hileman, Kathleen Harrington, Jeffery Iuliano, Yunyang Li, Tobias A. Marriage, Carolina Núñez, Matthew A. Petroff, Rodrigo A. Reeves, Rui Shi, Duncan J. Watts, Edward J. Wollack, and Zhilei Xu "Long-timescale stability in CMB observations at multiple frequencies using front-end polarization modulation", Proc. SPIE 12190, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, 121902Q (31 August 2022); https://doi.org/10.1117/12.2629723

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