A cryogenic half-wave plate polarimeter using a superconducting magnetic bearing

Klein, Jeff; Aboobaker, Asad M.; Ade, Peter A. R.; Aubin, F.; Baccigalupi, C.; Bao, Chaoyun; Borrill, J.; Chapman, David; Didier, Joy; Dobbs, M.; Gold, Benjamin; Grainger, William F.; Hanany, Shaul; Hubmayr, Johannes; Hillbrand, Seth; Grain, Julien; Jaffe, A. H.; Johnson, Bradley R.; Jones, T. J.; Kisner, T. S.; Korotkov, Andrei; Leach, S.; Lee, Adrian V.; Levinson, L. J.; Limon, M.; MacDermid, Kevin; Matsumura, Tomotake; Miller, Amber; Milligan, Michael; Pascale, Enzo; Polsgrove, Daniel; Ponthieu, N.; Raach, Kate; Reichborn-Kjennerud, Britt; Sagiv, Ilan; Stompor, R.; Tran, Hung V.; Tristram, M.; Tucker, Gregory S.; Yadav, Amit; Zaldarriaga, Matías; Zilic, Kyle

doi:10.1117/12.893669

Cited by 22 publications

(20 citation statements)

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“…For Simons Array, the position of the HWP will be at the Gregorian focus, since the cross-polarization performance is better than at the prime focus and a larger HWP has become available [33]. Additionally, a mechanism to rotate the HWP at cryogenic temperature is under development [49]. However, at the Gregorian focus, there will be two mirrors between the HWP and the sky.…”

Section: Systematic Uncertainties From the I→p Leakagementioning

confidence: 99%

Performance of a continuously rotating half-wave plate on the POLARBEAR telescope

Takakura

Aguilar

Akiba

et al. 2017

J. Cosmol. Astropart. Phys.

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A continuously rotating half-wave plate (CRHWP) is a promising tool to improve the sensitivity to large angular scales in cosmic microwave background (CMB) polarization measurements. With a CRHWP, single detectors can measure three of the Stokes parameters, I, Q and U , thereby avoiding the set of systematic errors that can be introduced by mismatches in the properties of orthogonal detector pairs. We focus on the implementation of CRHWPs in large aperture telescopes (i.e. the primary mirror is larger than the current maximum half-wave plate diameter of ∼ 0.5 m), where the CRHWP can be placed between the primary mirror and focal plane. In this configuration, one needs to address the intensity to polarization (I→P ) leakage of the optics, which becomes a source of 1/f noise and also causes differential gain systematics that arise from CMB temperature fluctuations. In this paper, we present the performance of a CRHWP installed in the Polarbear experiment, which employs a Gregorian telescope with a 2.5 m primary illumination pattern. The CRHWP is placed near the prime focus between the primary and secondary mirrors. We find that the I→P leakage is larger than the expectation from the physical properties of our primary mirror, resulting in a 1/f knee of 100 mHz. The excess leakage could be due to imperfections in the detector system, i.e. detector non-linearity in the responsivity and time-constant. We demonstrate, however, that by subtracting the leakage correlated with the intensity signal, the 1/f noise knee frequency is reduced to 32 mHz ( ∼ 39 for our scan strategy), which is very promising to probe the primordial B-mode signal. We also discuss methods for further noise subtraction in future projects where the precise temperature control of instrumental components and the leakage reduction will play a key role.

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Section: Systematic Uncertainties From the I→p Leakagementioning

confidence: 99%

Performance of a continuously rotating half-wave plate on the POLARBEAR telescope

Takakura

Aguilar

Akiba

et al. 2017

J. Cosmol. Astropart. Phys.

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“…Hanany et al (2003) proposed using an SMB for continuous rotation of an HWP and demonstrated a prototype system. Additional papers present the characterization of the coefficient of friction, vibrational amplitudes, resonant frequencies, and sources of power dissipation (Hull et al 1994;Matsumura 2006) and discuss the implementation of this system in the EBEX 2010 North American test flight (Klein et al 2011). In this section we review the EBEX2013 implementation (see also Klein 2014).…”

Section: Continuous Rotation Mechanismmentioning

confidence: 99%

“…Several other publications give additional details about the EBEX experiment. Some are from earlier stages of the program (Oxley et al 2004;Grainger et al 2008;Aubin et al 2010;Milligan et al 2010;Reichborn-Kjennerud et al 2010;Klein et al 2011;Sagiv et al 2012;Westbrook et al 2012), and others discuss some subsystems in more detail (Polsgrove 2009;Reichborn-Kjennerud 2010;Sagiv 2011;Aubin 2012;MacDermid 2014;MacDermid et al 2014;Westbrook 2014;Zilic 2014;Chapman 2015;Chapman et al 2015;Didier et al 2015;Aubin et al 2016;Didier 2016).…”

Section: Introductionmentioning

confidence: 99%

The EBEX Balloon-borne Experiment—Optics, Receiver, and Polarimetry

Aboobaker

Ade

Araujo

et al. 2018

ApJS

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The E and B Experiment (EBEX) was a long-duration balloon-borne cosmic microwave background (CMB) polarimeter that flew over Antarctica in 2012. We describe the experiment's optical system, receiver, and polarimetric approach and report on their in-flight performance. EBEX had three frequency bands centered on 150, 250, and 410GHz. To make efficient use of limited mass and space, we designed a 115cm 2 sr highthroughput optical system that had two ambient temperature mirrors and four antireflection-coated polyethylene lenses per focal plane. All frequency bands shared the same optical train. Polarimetry was achieved with a continuously rotating achromatic half-wave plate (AHWP) that was levitated with a superconducting magnetic bearing (SMB). This is the first use of an SMB in astrophysics. Rotation stability was 0.45% over a period of 10 hr, and angular position accuracy was 0°. 01. The measured modulation efficiency was above 90% for all bands. To our knowledge the 109% fractional bandwidth of the AHWP was the broadest implemented to date. The receiver, composed of one lens and the AHWP at a temperature of 4K, the polarizing grid and other lenses at 1K, and the two focal planes at 0.25K, performed according to specifications, giving focal plane temperature stability with a fluctuation power spectrum that had a 1/f knee at 2mHz. EBEX was the first balloon-borne instrument to implement technologies characteristic of modern CMB polarimeters, including high-throughput optical systems, and large arrays of transition edge sensor bolometric detectors with multiplexed readouts.

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“…We use an optical encoder and the Hall sensor to the PM rotor to track the AHWP position without contact. 16 …”

Section: Polarization Modulatormentioning

confidence: 99%

POLARBEAR-2 optical and polarimeter designs

et al. 2012

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POLARBEAR-2 is a ground based cosmic microwave background (CMB) radiation experiment observing from Atacama, Chile. The science goals of POLARBEAR-2 are to measure the CMB polarization signals originating from the inflationary gravity-wave background and weak gravitational lensing. In order to achieve these science goals, POLARBEAR-2 employs 7588 polarization sensitive transition edge sensor bolometers at observing frequencies of 95 and 150 GHz with 5.5 and 3.5 arcmin beam width, respectively. The telescope is the off-axis Gregorian, Huan Tran Telescope, on which the POLARBEAR-1 receiver is currently mounted. The polarimetry is based on modulation of the polarized signal using a rotating half-wave plate and the rotation of the sky. We present the developments of the optical and polarimeter designs including the cryogenically cooled refractive optics that achieve the overall 4 degrees field-of-view, the thermal filter design, the broadband anti-reflection coating, and the rotating half-wave plate.

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A cryogenic half-wave plate polarimeter using a superconducting magnetic bearing

Cited by 22 publications

References 0 publications

Performance of a continuously rotating half-wave plate on the POLARBEAR telescope

Performance of a continuously rotating half-wave plate on the POLARBEAR telescope

The EBEX Balloon-borne Experiment—Optics, Receiver, and Polarimetry

POLARBEAR-2 optical and polarimeter designs

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