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A cryogenic continuously rotating half-wave plate mechanism for the POLARBEAR-2b cosmic microwave background receiver

Hill, C. A. and Kusaka, A. and Ashton, P. and Barton, P. and Adkins, T. and Arnold, K. and Bixler, B. and Ganjam, S. and Lee, A. T. and Matsuda, F. and Matsumura, T. and Sakurai, Y. and Tat, R. and Zhou, Y. (2020) A cryogenic continuously rotating half-wave plate mechanism for the POLARBEAR-2b cosmic microwave background receiver. Review of Scientific Instruments, 91 (12). Art. No. 124503. ISSN 0034-6748. https://resolver.caltech.edu/CaltechAUTHORS:20210112-135210322

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Abstract

We present the design and laboratory evaluation of a cryogenic continuously rotating half-wave plate (CHWP) for the POLARBEAR-2b (PB-2b) cosmic microwave background receiver, the second installment of the Simons Array. PB-2b will observe at 5200 m elevation in the Atacama Desert of Chile in two frequency bands centered at 90 GHz and 150 GHz. In order to suppress atmospheric 1/f noise and mitigate systematic effects that arise when differencing orthogonal detectors, PB-2b modulates linear sky polarization using a CHWP rotating at 2 Hz. The CHWP has a 440 mm clear aperture diameter and is cooled to ≈50 K in the PB-2b receiver cryostat. It consists of a low-friction superconducting magnetic bearing and a low-torque synchronous electromagnetic motor, which together dissipate <2 W. During cooldown, a grip-and-release mechanism centers the rotor to <0.5 mm, and during continuous rotation, an incremental optical encoder measures the rotor angle with a noise level of 0.1 μrad/√Hz. We discuss the experimental requirements for the PB-2b CHWP, the designs of its various subsystems, and the results of its evaluation in the laboratory. The presented CHWP has been deployed to Chile and is expected to see first light on PB-2b in 2020 or 2021.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1063/5.0029006DOIArticle
https://arxiv.org/abs/2009.03972arXivDiscussion Paper
ORCID:
AuthorORCID
Hill, C. A.0000-0002-2641-6878
Matsuda, F.0000-0003-0041-6447
Alternate Title:A cryogenic continuously rotating half-wave plate for the POLARBEAR-2b cosmic microwave background receiver
Additional Information:© 2020 The Author(s). Published under license by AIP Publishing. Submitted: 9 September 2020 • Accepted: 15 November 2020 • Published Online: 9 December 2020. The presented CHWP development at LBNL was supported in part by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Contract No. DE-AC02-05CH11231, as well as the LBNL Directed Research and Development (LDRD) Program. This work was also supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships (SULI) program. AK acknowledges the support from JSPS Leading Initiative for Excellent Young Researchers (LEADER) and from JSPS KAKENHI under Grant Nos. JP16K21744, JP18H05539, and JP19H00674. This work was additionally supported in part by the World Premier International Research Center Initiative (WPI), MEXT, Japan. PB-2b and Simons Array, whose activities are integrated into much of the presented work, are supported by the Simons Foundation, the Gordon and Betty Moore Foundation, the Templeton Foundation, and the National Science Foundation (NSF) under Grant Nos. AST-0618398 and AST-1212230. We thank Cory Lee in the LBNL Physics Division who fabricated and influenced many design choices during early-stage prototyping, and we thank Warner Carlisle, Gordon Long, Tommy Gutierrez, and Abel Gonzalez in the UC Berkeley Physics Department for machining, welding, and consulting on many of the CHWP’s large-diameter, tight-tolerance components. We thank Suzanne Staggs at Princeton University for loaning the CAPMAP Dewar, which was used for the presented LBNL testing, and we thank Lewis Hyatt for providing CAD drawings of CAPMAP. We thank Frank Werfel and Uta Flögel-Delor at ATZ in Germany for fruitful collaborative research that led to the presented large-diameter superconducting magnetic bearing, and we thank Carl Johnson, Carl Zhang, and Dr. Yong Ji at GHTOT for pushing the limits of sapphire manufacturing to enable sapphire HWPs for high-throughput CMB instruments. We thank Muhammad Suri at SMC Corporation for many suggestions and ideas around robust gripper operation, and we thank Tijmen de Haan and Darcy Barron for useful discussions about SQUIDs in ambient magnetic fields. We want to recognize the bright and talented scientists who worked as undergraduates on the CHWP development at LBNL and UC Berkeley: Richard Chen, Hawkins Clay, Alexander Droster, Andrew Fischer, Mael Flament, Chingam Fong, Samantha Gilbert, Grant Hall, Arian Jadbabaie, Alex Madurowicz, Adam Rutkowski, and Danielle Sponseller. We also want to recognize the broader PB-2b and Simons Array team members who have helped with and consulted on a plethora of CHWP-related areas, including receiver integration, analysis considerations, data acquisition implementation, and detector/readout implications: Darcy Barron, Yuji Chinone, Tucker Elleflot, Neil Goeckner-Wald, John Groh, Logan Howe, Jennifer Ito, Oliver Jeong, Lindsay Lowry, Marty Navaroli, Haruki Nishino, Toki Suzuki, Praween Siritanasak, Nate Stebor, Satoru Takakura, and Calvin Tsai. Finally, we thank the reviewers, whose suggestions improved the clarity of several discussions throughout the paper. DATA AVAILABILITY. The data that support the findings of this study are available from the corresponding author upon reasonable request.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC02-05CH11231
Lawrence Berkeley National LaboratoryUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)JP16K21744
Japan Society for the Promotion of Science (JSPS)JP18H05539
Japan Society for the Promotion of Science (JSPS)JP19H00674
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Simons FoundationUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
John Templeton FoundationUNSPECIFIED
NSFAST-0618398
NSFAST-1212230
Issue or Number:12
Record Number:CaltechAUTHORS:20210112-135210322
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210112-135210322
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107439
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:13 Jan 2021 15:16
Last Modified:13 Jan 2021 15:16

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