Design and characterization of the Cosmology Large Angular Scale Surveyor (CLASS) 93 GHz focal plane

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https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10708/107081Y/Design-and-characterization-of-the-Cosmology-Large-Angular-Scale-Surveyor/10.1117/12.2311812.short

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https://doi.org/10.1117/12.2311812
 http://hdl.handle.net/11603/25041

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UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)

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https://orcid.org/0000-0001-9238-4918

Date

2018-07-09

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Conference papers and proceedings
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Citation of Original Publication

Sumit Dahal, et al. "Design and characterization of the Cosmology Large Angular Scale Surveyor (CLASS) 93 GHz focal plane," Proc. SPIE 10708, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX, 107081Y (9 July 2018); https://doi-org/10.1117/12.2311812

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

The Cosmology Large Angular Scale Surveyor (CLASS) aims to detect and characterize the primordial Bmode signal and make a sample-variance-limited measurement of the optical depth to reionization. CLASS is a ground-based, multi-frequency microwave polarimeter that surveys 70% of the microwave sky every day from the Atacama Desert. The focal plane detector arrays of all CLASS telescopes contain smooth-walled feedhorns that couple to transition-edge sensor (TES) bolometers through symmetric planar orthomode transducer (OMT) antennas. These low noise polarization-sensitive detector arrays are fabricated on mono-crystalline silicon wafers to maintain TES uniformity and optimize optical efficiency throughout the wafer. In this paper, we discuss the design and characterization of the first CLASS 93 GHz detector array. We measure the dark parameters, bandpass, and noise spectra of the detectors and report that the detectors are photon-noise limited. With current array yield of 82%, we estimate the total array noise-equivalent power (NEP) to be 2.1 aW√s.