A Large-Diameter Cryogenic Rotation Stage for Half-Wave Plate Polarization Modulation on the POLARBEAR-2 Experiment

C. A. Hill, A. Kusaka, P. Barton, B. Bixler, A. G. Droster, M. Flament, S. Ganjam, A. Jadbabaie, O. Jeong, A. T. Lee, A. Madurowicz, F. T. Matsuda, T. Matsumura, A. Rutkowski, Y. Sakurai, D. R. Sponseller, A. Suzuki, R. Tat

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

We describe the design of a cryogenic rotation stage (CRS) for use with the cryogenic half-wave plate (CHWP) polarization modulator on the POLARBEAR-2b and POLARBEAR-2c (PB2b/c) cosmic microwave background (CMB) experiments, the second and third installments of the Simons Array. Rapid modulation of the CMB polarization signal using a CHWP suppresses 1/f contamination due to atmospheric turbulence and allows a single polarimeter to measure both polarization states, mitigating systematic effects that arise when differencing orthogonal detectors. To modulate the full detector array while avoiding excess photon loading due to thermal emission, the CHWP must have a clear-aperture diameter of > 450 mm and be cooled to < 100 K. We have designed a 454 mm clear-aperture, < 65 K CRS using a superconducting magnetic bearing driven by a synchronous magnetic motor. We present the specifications for the CRS, its interfacing to the PB2b/c receiver cryostat, its performance in a stand-alone test, and plans for future work.

Original languageEnglish
Pages (from-to)851-859
Number of pages9
JournalJournal of Low Temperature Physics
Volume193
Issue number5-6
DOIs
Publication statusPublished - Dec 1 2018
Externally publishedYes

Keywords

  • Cosmic microwave background
  • Cryogenic
  • Half-wave plate
  • Modulation
  • POLARBEAR
  • Polarization
  • Superconducting magnetic bearing

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

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