The Cosmology Large Angular Scale Surveyor consists of four instruments performing a CMB polarization survey. Currently, the 40 GHz and first 90 GHz instruments are deployed and observing, with the second 90 GHz and a multichroic 150/220 GHz instrument to follow. The receiver is a central component of each instrument's design and functionality. This paper describes the CLASS receiver design, using the first 90 GHz receiver as a primary reference. Cryogenic cooling and filters maintain a cold, low-noise environment for the detectors. We have achieved receiver detector temperatures below 50 mK in the 40 GHz instrument for 85% of the initial 1.5 years of operation, and observed in-band efficiency that is consistent with pre-deployment estimates. At 90 GHz, less than 26% of in-band power is lost to the filters and lenses in the receiver, allowing for high optical efficiency. We discuss the mounting scheme for the filters and lenses, the alignment of the cold optics and detectors, stray light control, and magnetic shielding.
@article{arxiv.1807.04167,
title = {The Cosmology Large Angular Scale Surveyor Receiver Design},
author = {Jeffrey Iuliano and Joseph Eimer and Lucas Parker and Gary Rhoades and Aamir Ali and John W. Appel and Charles Bennett and Michael Brewer and Ricardo Bustos and David Chuss and Joseph Cleary and Jullianna Couto and Sumit Dahal and Kevin Denis and Rolando Dünner and Thomas Essinger-Hileman and Pedro Fluxa and Mark Halpern and Kathleen Harrington and Kyle Helson and Gene Hilton and Gary Hinshaw and Johannes Hubmayr and John Karakla and Tobias Marriage and Nathan Miller and Jeffrey John McMahon and Carolina Nuñez and Ivan Padilla and Gonzalo Palma and Matthew Petroff and Bastian Pradenas Márquez and Rodrigo Reeves and Carl Reintsema and Karwan Rostem and Deniz Augusto Nunes Valle and Trevor Van Engelhoven and Bingjie Wang and Qinan Wang and Duncan Watts and Jenet Weiland and Edward J. Wollack and Zhilei Xu and Ziang Yan and Lingzhen Zeng},
journal= {arXiv preprint arXiv:1807.04167},
year = {2018}
}