The Cosmology Large Angular Scale Surveyor (CLASS) aims to detect and characterize the primordial B-mode 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 aWs.
@article{arxiv.1807.03927,
title = {Design and characterization of the Cosmology Large Angular Scale Surveyor (CLASS) 93 GHz focal plane},
author = {Sumit Dahal and Aamir Ali and John W. Appel and Thomas Essinger-Hileman and Charles Bennett and Michael Brewer and Ricardo Bustos and Manwei Chan and David T. Chuss and Joseph Cleary and Felipe Colazo and Jullianna Couto and Kevin Denis and Rolando Dünner and Joseph Eimer and Trevor Engelhoven and Pedro Fluxa and Mark Halpern and Kathleen Harrington and Kyle Helson and Gene Hilton and Gary Hinshaw and Johannes Hubmayr and Jeffrey Iuliano and Tobias Marriage and Jeffrey McMahon and Nathan Miller and Carolina Nuñez and Ivan Padilla and Gonzalo Palma and Lucas Parker and Matthew Petroff and Bastian Pradenas and Rodrigo Reeves and Carl Reintsema and Karwan Rostem and Marco Sagliocca and Kongpop U-Yen and Deniz Valle and Bingjie Wang and Qinan Wang and Duncan Watts and Janet Weiland and Edward Wollack and Zhilei Xu and Ziang Yan and Lingzhen Zen},
journal= {arXiv preprint arXiv:1807.03927},
year = {2018}
}