A Large-Diameter Cryogenic Rotation Stage for Half-Wave Plate Polarization Modulation on the POLARBEAR-2 Experiment
A Large-Diameter Cryogenic Rotation Stage for Half-Wave Plate Polarization Modulation on the POLARBEAR-2 Experiment
复制标题
POLARBEAR-2 实验中用于半波片偏振调制的大直径低温旋转台
DOI：
10.1007/s10909-018-1980-6
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发表时间：
2018
影响因子：
2
通讯作者：
Tat R.
中科院分区：
文献类型：
--
作者：
Hill C. A.;Kusaka A.;Barton P.;Bixler B.;Droster A. G.;Flament M.;Ganjam S.;Jadbabaie A.;Jeong O.;Lee A. T.;Madurowicz A.;Matsuda F. T.;Matsumura T.;Rutkowski A.;Sakurai Y.;Sponseller D. R.;Suzuki A.;Tat R.
我们描述了在西蒙斯阵列的第二和第三部分--极地-2b和极-2c(PB2b/c)宇宙微波背景(CMB)实验中，用于低温半波片(CHWP)偏振调制器的低温旋转台(CRS)的设计。使用CHWP对CMB偏振信号进行快速调制可抑制大气湍流造成的1/f污染，并允许单个偏振仪测量两种偏振状态，从而减轻了对正交探测器进行差动时产生的系统影响。为了调制整个探测器阵列，同时避免由于热发射而产生的过量光子负载，CHWP的净孔直径必须为450K，并必须冷却到100K。我们设计了454 mm净孔，65K CRS，它使用了由同步磁电机驱动的超导磁轴承。我们介绍了CRS的规格，它与PB2b/c接收器低温恒温器的接口，它在独立测试中的性能，以及未来工作的计划。
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/fcontamination 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.