BICEP Array: 150 GHz detector module development

• Main Authors: Schillaci, A., Ade, P. A. R., Ahmed, Z., Amiri, M., Barkats, D., Thakur, R. Basu, Bischoff, C. A., Beck, D., Bock, J. J., Buza, V., Cheshire, J., Connors, J., Cornelison, J., Crumrine, M., Cukierman, A., Denison, E., Dierickx, M., Duband, L., Eiben, M., Fatigoni, S., Filippini, J. P., Giannakopoulos, C., Goeckner-Wald, N., Goldfinger, D., Grayson, J. A., Grimes, P., Hall, G., Halal, G., Halpern, M., Hand, E., Harrison, S., Henderson, S., Hildebrandt, S. R., Hilton, G. C., Hubmayr, J., Hui, H., Irwin, K. D., Kang, J., Karkare, K. S., Kefeli, S., Kovac, J. M., Kuo, C. L., Lau, K., Leitch, E. M., Lennox, A., Megerian, K. G., Miller, O. Y., Minutolo, L., Moncelsi, L., Nakato, Y., Namikawa, T., Nguyen, H. T., Brient, R. O', Palladino, S., Petroff, M., Precup, N., Prouve, T., Pryke, C., Racine, B., Reintsema, C. D., Schmitt, B. L., Singari, B., Soliman, A., Germaine, T. St., Steinbach, B., Sudiwala, R. V., Thompson, K. L., Tucker, C., Turner, A. D., Umiltá, C., Verges, C., Vieregg, A. G., Wandui, A., Weber, A. C., Wiebe, D. V., Willmert, J., Wu, W. L. K., Yang, E., Yoon, K. W., Young, E., Yu, C., Zeng, L., Zhang, C., Zhang, S.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2021
• Subjects: Instrumentation and Methods for Astrophysics astro-ph.IM; Cosmology and Nongalactic Astrophysics astro-ph.CO; FOS Physical sciences; South Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.2111.14785; https://arxiv.org/abs/2111.14785

The BICEP/Keck Collaboration is currently leading the quest to the highest sensitivity measurements of the polarized CMB anisotropies on degree scale with a series of cryogenic telescopes, of which BICEP Array is the latest Stage-3 upgrade with a total of $\sim32,000$ detectors. The instrument comprises 4 receivers spanning 30 to 270 GHz, with the low-frequency 30/40 GHz deployed to the South Pole Station in late 2019. The full complement of receivers is forecast to set the most stringent constraints on the tensor to scalar ratio $r$. Building on these advances, the overarching small-aperture telescope concept is already being used as the reference for further Stage-4 experiment design. In this paper I will present the development of the BICEP Array 150 GHz detector module and its fabrication requirements, with highlights on the high-density time division multiplexing (TDM) design of the cryogenic circuit boards. The low-impedance wiring required between the detectors and the first-stage SQUID amplifiers is crucial to maintain a stiff voltage bias on the detectors. A novel multi-layer FR4 Printed Circuit Board (PCB) with superconducting traces, capable of reading out up to 648 detectors, is presented along with its validation tests. I will also describe an ultra-high density TDM detector module we developed for a CMB-S4-like experiment that allows up to 1,920 detectors to be read out. TDM has been chosen as the detector readout technology for the Cosmic Microwave Background Stage-4 (CMB-S4) experiment based on its proven low-noise performance, predictable costs and overall maturity of the architecture. The heritage for TDM is rooted in mm- and submm-wave experiments dating back 20 years and has since evolved to support a multiplexing factor of 64x in Stage-3 experiments. : 9 pages, 5 figure, Proceeding of LTD19 submitted to Journal of Low Temperature Physics