We present a novel system to calibrate millimeter-wave polarimeters for CMB polarization measurements. This technique is an extension of the conventional metal mirror rotation approach, however it employs cryogenically-cooled blackbody absorbers. The primary advantage of this system is that it can generate a slightly polarized signal ($\sim100$ mK) in the laboratory; this is at a similar level to that measured by ground-based CMB polarization experiments observing a $\sim$ 10 K sky. It is important to reproduce the observing condition in the laboratry for reliable characterization of polarimeters before deployment. In this paper, we present the design and principle of the system, and demonstrate its use with a coherent-type polarimeter used for an actual CMB polarization experiment. This technique can also be applied to incoherent-type polarimeters and it is very promising for the next-generation CMB polarization experiments.
The Precursor Small Aperture Telescope (PreSAT) CMB polarimeter
Center for Astrophysics, Harvard & Smithsonian（哈佛-史密森天体物理中心）；Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory（卡弗里粒子天体物理学与宇宙学研究所，SLAC国家加速器实验室）；Department of Physics, California Institute of Technology（加州理工学院物理系）；Jet Propulsion Laboratory（喷气推进实验室）；Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota（明尼苏达大学物理与天文学院天体物理研究所）；Department of Physics and Astronomy, University of Pennsylvania（宾夕法尼亚大学物理与天文学系）；Department of Physics, Enrico Fermi Institute, Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学物理系，恩里科·费米研究所，卡弗里宇宙物理学研究所）
Sub-Kelvin Cryogenics for a Super-Pressure Balloon-Borne CMB Polarimeter: Taurus
Case Western Reserve University（凯斯西储大学）；University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；National Institute of Standards and Technology（美国国家标准与技术研究院）；Princeton University（普林斯顿大学）；University of Colorado Boulder（科罗拉多大学博尔德分校）；University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；University of Iceland（冰岛大学）；Stockholm University（斯德哥尔摩大学）
LiteBIRD是测量宇宙微波背景辐射偏振的下一代卫星飞行任务。在大角度尺度上，宇宙微波背景的B模式偏振带有原始引力波的印记，它的精确测量将为暴胀时代提供强有力的探测。LiteBIRD的目标是实现表征张量与标量之比$r$的测量，其不确定度为$δr=0.001$。为了实现这一目标，我们将在低温冷却的亚开尔文焦平面上采用千像素超导探测器阵列，光学系统的温度为4~K。我们目前正在考虑两个探测器阵列的选择;过渡边缘传感器（TES）测辐射热计和微波动力学电感探测器（MKID）。在本文中，我们给出了一个LiteBIRD的概述，并描述了一个基于TES的偏振计设计，以实现2~ $μ$ K $\cdot$ arcmin的目标灵敏度在50至320~GHz的频率范围。
QUBIC: using NbSi TESs with a bolometric interferometer to characterize the polarisation of the CMB
QUBIC（Q \& U Bolometric Interferometer for Cosmology）是一个国际地面实验，专门用于测量宇宙微波背景（CMB）的偏振起伏。它是基于测热干涉测量，一个原始的检测技术相结合的免疫系统的影响与低温非相干探测器的灵敏度的干涉仪。QUBIC将部署在阿根廷萨尔塔省San Antonio de los Cobres附近的Alto Chorrillos山区。QUBIC检测链由2048个冷却至350 mK的NbSi跃迁边缘传感器（TES）组成。电压偏置的TES通过基于1 K超导量子干涉器件（SQUID）和60 K新型SiGe专用集成电路（ASIC）的时域多路复用读取，从而实现前所未有的复用（MUX）因子128。QUBIC实验目前正在实验室中进行表征，在升级到完整仪器之前，减少了探测器的数量。我将介绍这个表征阶段的最后结果，重点是探测器和读出系统。
