2018/06/14 by L. Howe, Howe, Logan, Calvin Tsai +24
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Cosmology and Gravitation Theories #FOS: Physical sciences #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Radio Astronomy Observations and Technology #Superconducting and THz Device Technology
paper · pdf · doi:10.48550/arxiv.1806.05576
openalex publication_date 2018/06/14 · openalex created_date 2022/10/06 · openalex updated_date 2026/08/01
The POLARBEAR-2/Simons Array Cosmic Microwave Background (CMB) polarization\nexperiment is an upgrade and expansion of the existing POLARBEAR-1 (PB-1)\nexperiment, located in the Atacama desert in Chile. Along with the CMB\ntemperature and E-mode polarization anisotropies, PB-1 and the Simons Array\nstudy the CMB B-mode polarization anisotropies produced at large angular\nscales by inflationary gravitational waves, and at small angular scales by\ngravitational lensing. These measurements provide constraints on various\ncosmological and particle physics parameters, such as the tensor-to-scalar\nratio r, and the sum of the neutrino masses. The Simons Array consists of\nthree 3.5 m diameter telescopes with upgraded POLARBEAR-2 (PB-2) cryogenic\nreceivers, named PB-2a, -2b, and -2c. PB-2a and -2b will observe the CMB over\nmultiple bands centered at 95 GHz and 150 GHz, while PB-2c will observe at 220\nGHz and 270 GHz, which will enable enhanced foreground separation and\nde-lensing. Each Simons Array receiver consists of two cryostats which share\nthe same vacuum space: an optics tube containing the cold reimaging lenses and\nLyot stop, infrared-blocking filters, and cryogenic half-wave plate; and a\nbackend which contains the focal plane detector array, cold readout components,\nand millikelvin refrigerator. Each PB-2 focal plane array is comprised of 7,588\ndual-polarization, multi-chroic, lenslet- and antenna-coupled, Transition Edge\nSensor (TES) bolometers which are cooled to 250 mK and read out using\nSuperconducting Quantum Interference Devices (SQUIDs) through a digital\nfrequency division multiplexing scheme with a multiplexing factor of 40. In\nthis work we describe progress towards commissioning the PB-2b and -2c\nreceivers including cryogenic design, characterization, and performance of both\nthe PB-2b and -2c backend cryostats.\n