Large Angular Scale Polarization Survey of the Cosmic Microwave Background

该合同将资助位于智利阿塔卡马沙漠的宇宙学大角尺度勘测者（CLASS）宇宙微波背景（CMB）极化实验的调试和运行。计划中的两个望远镜中的第一个最近已经部署。主要的科学目标是探测一种极化信号，这种信号起源于大爆炸最初时刻宇宙的理论快速膨胀。这项工作更广泛的影响包括培养本科生、研究生和博士后。该项目还有一个综合的公共宣传计划，通过每年一次的约翰霍普金斯大学物理博览会，完善的培训高中教师的夸克网计划，以及在巴尔的摩城市学校的互动天文馆展示大量未被充分代表的少数民族，吸引巴尔的摩公众。最终，两台望远镜将在40,90,150和220ghz的频率上进行观测。CLASS仪器的一个新颖之处在于它的第一个光学元件是可变偏振调制器（与平镜的可变偏移的线栅）。主要的科学目标是在大约10度的角尺度上寻找暴胀引力波b模偏振信号，这与CMB角功率谱中的再电离“碰撞”有关。另一个科学目标是通过测量与再电离信号相关的电子模式来提高再电离时代对CMB光子的电子散射光学深度。望远镜和其他测量仪器的开发已经得到了NSF主要研究仪器项目的两项资助。

This award will fund commissioning and operations of the Cosmology Large Angular Scale Surveyor (CLASS) cosmic microwave background (CMB) polarization experiment located in the Atacama Desert in Chile. The first of two planned telescopes was recently deployed. The main science goal is to detect a polarization signal originating in a theorized rapid inflation of the universe during the first moments of the Big Bang. Broader impacts of the work include training of undergraduate students, graduate students, and postdocs. The project also has an integrated program of public outreach to engage the Baltimore public through the annual Johns Hopkins University Physics Fair, the well-established Quarknet program that trains high school teachers, and interactive planetarium shows at Baltimore city schools with large populations of under-represented minorities.Ultimately, two telescopes will make observations at frequencies of 40, 90, 150, and 220 GHz. A novel aspect of the CLASS instrumentation is that its first optical element is a variable polarization modulator (wire grid with variable offset from a flat mirror). The main science goal is to search for the inflationary gravitational wave B-mode polarization signal on angular scales of roughly 10 degrees, associated with the reionization 'bump' in the CMB angular power spectrum. Another science goal is to improve the electron-scattering optical depth of the reionization era to CMB photons by measuring the E-modes associated with the reionization signal. Development of the telescopes and other instrumentation to conduct the survey has been supported via two previous awards from NSF's Major Research Instrumentation program.