MRI-R2: Development of POLAR-1, an expandable 5,000-detector CMB Polarimeter

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。宇宙微波背景(CMB)观测保存了关于早期宇宙的大量信息，它们最近将宇宙学转变为一门精密科学。虽然膨胀宇宙的基本概念和组成要素已经确立，但关于宇宙起源的根本问题仍然没有得到回答。测量CMB极化为解决其中最重要的问题提供了一个强有力的工具。CMB中的偏振模式可以分解为两个不同的分量，E模和B模，后者(尚未被检测)可以提供两个显著的见解。利用探测到的B模偏振，可以研究宇宙的大尺度结构以及影响这种结构的参数，如绝对中微子质量和暗能量演化。度级尺度的B模偏振也应该带有来自宇宙引力波背景(CGB)的印记，让我们得以一窥宇宙在生命第一秒的最微小部分(10^-35)。这个CGB信号是对膨胀大爆炸发生时能量尺度的直接测量。该提案要求提供资金，用于开发增强型大幅面焦平面偏振测量仪Polar-1，该仪器配有4 608个偏振敏感超导测辐射热计，工作频率为150 GHz，并与1.5米反射式射电望远镜集成在一起。提出的角分辨率和测辐射热计阵列大小的组合使其非常适合于研究透镜诱导的B偏振和CGB产生的B偏振。Polal-1将探测透镜诱导的B偏振，具有极高的意义，并在功率上搜索CGB，直到初始微扰的2%。该项目的更广泛影响将是它的寻路性质，即建造一台对CMB两极分化的敏感度提高约10倍的仪器。由于宇宙学激发了公众的想象力，它是激发学生对科学感兴趣的一种非常有效的工具。该项目将继续通过将研究生和本科教育与技术和仪器开发、天文野外观测和科学分析相结合，为培养下一代科学家作出重大贡献。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The Cosmic Microwave Background (CMB) observations hold a remarkable wealth of information about the early Universe and they recently transformed cosmology into a precision science. While the basic notion and the ingredients of an expanding Universe are well established, fundamental questions on the Universe's origin still remain unanswered. Measuring the CMB polarization provides a powerful tool to address the most important of these questions. The polarization pattern in the CMB can be decomposed into two distinct components, E-mode and B-mode, and the latter (yet to be detected) can provide two remarkable insights. With the detected B-mode polarization, one can study the large-scale structure of the Universe and the parameters that affect this structure, such as absolute neutrino mass and Dark Energy evolution. The degree-scale B-mode polarization also should carry imprints from the Cosmic Gravitational-wave Background (CGB), giving us a glimpse of the Universe during its tiniest (10^-35) fraction of the very first second of life. This CGB signal is a direct measurement of the energy scale at which the inflationary Big Bang occurs. The proposal requests funds for development of an enhanced large-format focal plane polarimeter POLAR-1 with 4,608 polarization-sensitive superconducting bolometers operating at 150 GHz and integrated with a 1.5-m reflective radio telescope. The proposed combination of angular resolution and bolometer array size make it ideally suited to study both the lensing-induced and the CGB-generated B-polarization. POLAR-1 will detect lensing induced B-polarization with extremely high significance and search for CGB down to 2% of the initial perturbation in power. The project's broader impacts would be in its path-finding nature of building an instrument ~10x more sensitive to the CMB polarization. As cosmology captures the public imagination, it is a remarkably effective vehicle for stimulating students' interest in science. The project will continue contributing significantly to the training of next generation of scientists by integrating graduate and undergraduate education with technology and instrumentation development, astronomical field observations, and scientific analysis.