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

Hill, Charles A.; Kusaka, A.; Barton, Paul; Bixler, Bryce; Droster, Alex; Flament, Mael; Ganjam, Suhas; Jadbabaie, Arian; Jeong, O.; Lee, Adrian T.; Madurowicz, Alex; Matsuda, F.; Matsumura, Tomotake; Rutkowski, A.; Sakurai, Y.; Danielle, Sponseller,; Suzuki, Aritoki; Tat, Raymond

doi:10.1007/s10909-018-1980-6

Cited by 19 publications

(13 citation statements)

References 23 publications

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“…EBEX was also the first astrophysics experiment to implement an SMB. This system is also baselined for a groundbased and a proposed space mission (Iida et al 2017;Hill et al 2018). EBEX was a successful technology pathfinder for future CMB space missions.…”

Section: Discussionmentioning

confidence: 99%

The EBEX Balloon-borne Experiment—Detectors and Readout

Abitbol¹,

Aboobaker²,

Araujo³

et al. 2018

ApJS

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EBEX was a long-duration balloon-borne experiment to measure the polarization of the cosmic microwave background. The experiment had three frequency bands centered at 150, 250, and 410GHz and was the first to use a kilopixel array of transition edge sensor bolometers aboard a balloon platform. We describe the design and characterization of the array and the readout system. From the lowest to highest frequency, the median measured detectors' average thermal conductances were 39, 53, and 63pW/K, the medians of transition temperatures were 0.45, 0.48, and 0.47K, and the medians of normal resistances were 1.9, 1.5, and 1.4Ω; we also give the measured distributions. With the exception of the thermal conductance at 150GHz, all measured values are within 30% of their design. We measure median low-loop-gain time constants τ 0 = 88, 46, and 57ms. Two measurements of bolometer absorption efficiency gave results consistent within 10% and showing high (∼0.9) efficiency at 150GHz and medium (∼0.35 and ∼0.25) efficiency at the two higher bands. We measure a median total optical power absorbed of 3.6, 5.3, and 5.0pW. EBEX pioneered the use of the digital version of the frequency domain multiplexing system. We multiplexed the bias and readout of 16 bolometers onto two wires. The median per-detector noise-equivalent temperatures are 400, 920, and 14,500 mK s cmb. We compare these values to our preflight predictions and to a previous balloon payload. We discuss the sources of excess noise and the path for a future payload to make full use of the balloon environment.

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Section: Discussionmentioning

confidence: 99%

The EBEX Balloon-borne Experiment—Detectors and Readout

Abitbol¹,

Aboobaker²,

Araujo³

et al. 2018

ApJS

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“…While stepped CHWPs have deployed on a variety of mm and sub-mm experiments, [26][27][28]32,33 the continuously rotating CHWP is an emerging technology. 24,[42][43][44] Operating a 500 mmdiameter, tens-of-kilogram, spinning instrument in a cryogenic vacuum space poses a menagerie of challenges, including differential thermal contraction, frictional dissipation, and cryomechanical durability. The PB-2b CHWP design addresses these challenges with several hardware advancements.…”

Section: Half-wave Plate Modulationmentioning

confidence: 99%

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

Hill

Kusaka

Ashton

et al. 2020

Review of Scientific Instruments

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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 (CMB) receiver, the second installment of the Simons Array. PB-2b will observe at 5,200 m elevation in the Atacama Desert of Chile in two frequency bands centered at 90 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 (SMB) 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.

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“…This coated lens technology has been well characterized and validated through an extensive ESA-funded Technical Research Programme (TRP) programme. In addition, such lenses, of similar sizes, have been manufactured by members of the project team, and successfully deployed on ground-based and balloon-borne CMB polarimetry experiments, such as POLAR-BEAR, 14 BICEP, 15 BICEP2, 8 SPIDER, 10 ACT, 16 Advanced ACT, 17 EBEX 18 etc. In addition, porous PTFE coated lenses have also been deployed in space on the Herschel-SPIRE 19 satellite instrument.…”

Section: Quasi-optical Components 321 Lensesmentioning

confidence: 99%

“…In order to minimize the thermal impact of such a rotating mechanism, it has been chosen to adopt a magnetic levitating rotor. 14,30 One polarization modulation system is designed for each of the telescopes. 31 The main characteristics and requirements of the HWP rotating mechanism are a spin rate of 39 rpm (61 rpm), HWP diameter of 320 mm (220 mm) and angular accuracy < 1 (< 5 ) for MFT (HFT).…”

Section: Polarization Modulator Unitsmentioning

confidence: 99%

Overview of the medium and high frequency telescopes of the LiteBIRD space mission

Montier

Mot

Bernardis

et al. 2020

Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave

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LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the Universe, through the measurements of their imprint onto the polarization of the cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over the full sky, at large angular scales, and over 15 frequency bands from 34 GHz to 448 GHz. The LiteBIRD instruments consist of three telescopes, namely the Low-, Mediumand High-Frequency Telescope (respectively LFT, MFT and HFT). We present in this paper an overview of the design of the Medium-Frequency Telescope (89-224 GHz) and the High-Frequency Telescope (166-448 GHz), the so-called MHFT, under European responsibility, which are two cryogenic refractive telescopes cooled down to 5 K. They include a continuous rotating half-wave plate as the first optical element, two high-density polyethylene (HDPE) lenses and more than three thousand transition-edge sensor (TES) detectors cooled to 100 mK. We provide an overview of the concept design and the remaining specific challenges that we have to face in order to achieve the scientific goals of LiteBIRD.

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

Cited by 19 publications

References 23 publications

The EBEX Balloon-borne Experiment—Detectors and Readout

The EBEX Balloon-borne Experiment—Detectors and Readout

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

Overview of the medium and high frequency telescopes of the LiteBIRD space mission

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