The Simons Observatory: Cryogenic half wave plate rotation mechanism for the small aperture telescopes-Reference-Cited by-同舟云学术

The Simons Observatory: Cryogenic half wave plate rotation mechanism for the small aperture telescopes

Published:2024-02-01 Issue:2 Volume:95 Page:
ISSN:0034-6748
Container-title:Review of Scientific Instruments
language:en
Short-container-title:

Author:

Yamada K.¹^ORCID,Bixler B.²^ORCID,Sakurai Y.³⁴^ORCID,Ashton P. C.⁴⁵⁶^ORCID,Sugiyama J.¹^ORCID,Arnold K.²^ORCID,Begin J.⁷^ORCID,Corbett L.⁵⁶^ORCID,Day-Weiss S.⁷^ORCID,Galitzki N.⁸⁹^ORCID,Hill C. A.⁵⁶^ORCID,Johnson B. R.¹⁰^ORCID,Jost B.⁴^ORCID,Kusaka A.¹⁴⁵^ORCID,Koopman B. J.¹¹^ORCID,Lashner J.¹¹^ORCID,Lee A. T.⁵⁶^ORCID,Mangu A.⁶^ORCID,Nishino H.¹²^ORCID,Page L. A.⁷^ORCID,Randall M. J.²^ORCID,Sasaki D.¹^ORCID,Song X.⁶^ORCID,Spisak J.²^ORCID,Tsan T.²^ORCID,Wang Y.⁷^ORCID,Williams P. A.⁵^ORCID

Affiliation:

1. Department of Physics, Graduate School of Science, The University of Tokyo 1 , Tokyo 113-0033, Japan

2. Department of Physics, University of California, San Diego 2 , La Jolla, California 92093, USA

3. Graduate School of Natural Science and Technology, Okayama University 3 , Okayama 700-8530, Japan

4. Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo 4 , Chiba 277-8583, Japan

5. Physics Division, Lawrence Berkeley National Laboratory 5 , Berkeley, California 94720, USA

6. Department of Physics, University of California 6 , Berkeley, California 94720, USA

7. Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University 7 , Princeton, New Jersey 08544, USA

8. Department of Physics, University of Texas at Austin 8 , Austin, Texas 78722, USA

9. Weinberg Institute for Theoretical Physics, Texas Center for Cosmology and Astroparticle Physics 9 , Austin, Texas 78712, USA

10. Department of Astronomy, University of Virginia 10 , Charlottesville, Virginia 22904, USA

11. Wright Laboratory, Department of Physics, Yale University 12 , New Haven, Connecticut 06520, USA

12. Research Center for the Early Universe, School of Science, The University of Tokyo 11 , Tokyo 113-0033, Japan

Abstract

We present the requirements, design, and evaluation of the cryogenic continuously rotating half-wave plate (CHWP) for the Simons Observatory (SO). SO is a cosmic microwave background polarization experiment at Parque Astronómico de Atacama in northern Chile that covers a wide range of angular scales using both small (⌀0.42 m) and large (⌀6 m) aperture telescopes. In particular, the small aperture telescopes (SATs) focus on large angular scales for primordial B-mode polarization. To this end, the SATs employ a CHWP to modulate the polarization of the incident light at 8 Hz, suppressing atmospheric 1/f noise and mitigating systematic uncertainties that would otherwise arise due to the differential response of detectors sensitive to orthogonal polarizations. The CHWP consists of a 505 mm diameter achromatic sapphire HWP and a cryogenic rotation mechanism, both of which are cooled down to ∼50 K to reduce detector thermal loading. Under normal operation, the HWP is suspended by a superconducting magnetic bearing and rotates with a constant 2 Hz frequency, controlled by an electromagnetic synchronous motor. We find that the number of superconductors and the number of magnets that make up the superconducting magnetic bearing are important design parameters, especially for the rotation mechanism’s vibration performance. The rotation angle is detected through an angular encoder with a noise level of 0.07 μrad s. During a cooldown process, the rotor is held in place by a grip-and-release mechanism that serves as both an alignment device and a thermal path. In this paper, we provide an overview of the SO SAT CHWP: its requirements, hardware design, and laboratory performance.

Funder

Japan Society for the Promotion of Science

High Energy Physics

Simons Foundation

Gordon and Betty Moore Foundation

Publisher

AIP Publishing

Link

https://pubs.aip.org/aip/rsi/article-pdf/doi/10.1063/5.0178066/19690477/024504_1_5.0178066.pdf

Reference97 articles.

1. Statistics of cosmic microwave background polarization;Phys. Rev. D,1997

2. All-sky analysis of polarization in the microwave background;Phys. Rev. D,1997

3. A probe of primordial gravity waves and vorticity;Phys. Rev. Lett.,1997

4. Signature of gravity waves in the polarization of the microwave background;Phys. Rev. Lett.,1997

Cited by 2 articles. 订阅此论文施引文献订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献

1. Effect of instrumental polarization with a half-wave plate on the B-mode signal: prediction and correction;Journal of Cosmology and Astroparticle Physics;2024-04-01

2. The Simons Observatory: Development and Optical Evaluation of Achromatic Half-Wave Plates;Journal of Low Temperature Physics;2024-01-30