BICEP / Keck XV: The BICEP3 CMB Polarimeter and the First Three Year Data Set

• Main Authors: Ade, P.A.R., Ahmed, Z., Amiri, M., Barkats, D., Thakur, R. Basu, Beck, D., Bischoff, C., Bock, J.J., Boenish, H., Bullock, E., Buza, V., Cheshire, J.R., Connors, J., Cornelison, J., Crumrine, M., Cukierman, A., Denison, E.V., Dierickx, M., Duband, L., Eiben, M., Fatigoni, S., Filippini, J.P., Fliescher, S., Goeckner-Wald, N., Goldfinger, D.C., Grayson, J., Grimes, P., Halal, G., Hall, 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., Karpel, E., Kefeli, S., Kernasovskiy, S.A., Kovac, J.M., Kuo, C.L., Lau, K., Leitch, E.M., Lennox, A., Megerian, K.G., Minutolo, L.
• Other Authors: Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), BICEP/Keck
• Format: Report
• Language: English
• Published: HAL CCSD 2021
• Subjects: cosmic background radiation: polarization; beam: width; beam: polarization; temperature; infrared; radio wave: detector; pole; optical; bolometer; BICEP; performance; optics; [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det]; [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; South Pole; South pole
• Online Access: https://hal.science/hal-03380647

We report on the design and performance of the BICEP3 instrument and its first three-year data set collected from 2016 to 2018. BICEP3 is a 52cm aperture, refracting telescope designed to observe the polarization of the cosmic microwave background (CMB) on degree angular scales at 95GHz. It started science observation at the South Pole in 2016 with 2400 antenna-coupled transition-edge sensor (TES) bolometers. The receiver first demonstrated new technologies such as large-diameter alumina optics, Zotefoam infrared filters, and flux-activated SQUIDs, allowing $\sim 10\times$ higher optical throughput compared to the Keck design. BICEP3 achieved instrument noise-equivalent temperatures of 9.2, 6.8 and 7.1$\mu\text{K}_{\text{CMB}}\sqrt{\text{s}}$ and reached Stokes $Q$ and $U$ map depths of 5.9, 4.4 and 4.4$\mu$K-arcmin in 2016, 2017 and 2018, respectively. The combined three-year data set achieved a polarization map depth of 2.8$\mu$K-arcmin over an effective area of 585 square degrees, which is the deepest CMB polarization map made to date at 95GHz.