MRI: Development of a 150 GHz Receiver for the BICEP Array CMB Polarimeter

目前建立的宇宙大爆炸理论的宇宙学模型留下了一个悬而未决的问题，即如何解释整个可观测宇宙是如何在亚核体积的戏剧性指数“膨胀”中产生的。在这个短暂的暴胀期之后，宇宙继续膨胀，但速度变慢了。据信，这种剧烈的时空膨胀会产生原始引力波，现在正在膨胀的宇宙中传播，从而形成宇宙引力波背景（CGB），其振幅可以衡量暴胀的能量尺度。CGB在宇宙微波背景（CMB）的极化中留下了微弱的特征，探测这种极化特征可以说是当今宇宙学中最重要的目标。作为BICEP阵列多机构实验的一部分，该合同支持开发用于研究CMB极化的150 GHz宽场接收机。BICEP阵列继续BICEP计划的CMB偏振测量，最终将在30、40、95、150、220和270 GHz六个频段工作，测量和消除银河系的极化发射，探测长期寻找的原始引力波信号。提出的MRI工作将：(a)在关键150 GHz频段的测量能力上提供一个巨大的飞跃，因为新的150 GHz接收器将使该频段的CMB测量速度比单个凯克阵列接收器快15倍，在该频率上部署时代表领先的测量能力；(b)利用NSF目前在开发BICEP阵列望远镜支架方面的投资，并承诺在2021年之前支持BICEP阵列的后勤、部署、运营和数据分析；(c)利用现有的私人资金建造30/40 GHz和95 GHz接收器，这将严格限制拟议的150 GHz仪器在适当灵敏度水平上的银河系同步辐射。这种发展是低风险的，并且结合了最近制造更大的探测器阵列所取得的重大技术进步。拟议的BICEP阵列计划是CMB- s4计划的探路者，该计划将建立最终的CMB偏振实验，该实验将结合部署在不同位置的许多（多达5-10）CMB望远镜。

The current established cosmological model for a theory of the Big Bang leaves open the question of explaining how the entire observable Universe being spawned in a dramatic, exponential "inflation" of a sub-nuclear volume. Following this short inflationary period, the Universe continues to expand, but at a less rapid rate. It is believed that this violent space-time expansion would have produced primordial gravitational waves now propagating through the expanding universe, thus forming a cosmic gravitational-wave background (CGB) the amplitude of which measures the energy scale of inflation. The CGB imprints a faint signature in the polarization of the Cosmic Microwave Background (CMB), and detecting this polarization signature is arguably the most important goal in cosmology today. This award supports the development of a 150 GHz wide-field receiver for studying the CMB polarization as part of the BICEP Array multi-institutional experiment. The BICEP Array continues the BICEP program of CMB polarization measurements and will ultimately operate in six frequency bands at 30, 40, 95, 150, 220 and 270 GHz to measure and remove polarized emission from the Milky Way Galaxy and detect the long-sought primordial gravitational waves signal. The proposed MRI effort will: (a) provide a large leap in measurement capability at the critical 150 GHz frequency band as the new 150 GHz receiver will make CMB measurements 15 times more rapidly than a single Keck Array receiver in this band, representing the leading measurement capability at this frequency when fielded; (b) leverage NSF's current investment in developing the BICEP Array telescope mount, and its commitment to supporting BICEP Array logistics, fielding, operations, and data analysis through 2021; and (c) leverage existing private funding to construct 30/40 and 95 GHz receivers that will place tight constraints on galactic synchrotron emission at the appropriate level of sensitivity for the proposed 150 GHz instrument. This development is low-risk and incorporates significant technological advances reached recently with fabrication of larger detector arrays. The proposed BICEP Array program is a pathfinder towards the CMB-S4 initiative to build ultimate CMB polarization experiments, which will combine many (up to 5-10) CMB telescopes deployed at different locations.