Ground-Based Astrophysics with the STACEE and Pierre Auger Observatories

该提案要求资金支持凯斯西储大学（CWRU）小组进行两项天体物理学实验。STACEE是一种新的地面伽玛射线天文探测器，能量范围在50到1000 GeV之间，对应于以前地面实验无法达到的能量状态。STACEE位于美国桑迪亚国家实验室的国家太阳能热测试设施（NSTTF），使用NSTTF的大型定日镜收集来自伽马射线空气阵风的切伦科夫光。STACEE实验的建设现在已经完成，但在建设期间进行了两次主要的观测活动。1998年，STACEE以超过6个标准差的显著性探测到了蟹状星云。在2001年夏天，STACEE在一次爆发中探测到了星系外的马卡里安421。在接下来的三年里，STACEE将观测活动星系核（AGN）、伽马射线暴（GRB）以及其他几个星系和星系外物体。在较低的能量阈值下，由于星系间的伽马吸收，在较高能量下无法观测到的更多星系外源将被STACEE观测到。STACEE可能具有独特的能力，可以对50至250 GeV的能量范围内的源进行扩展观测。CWRU的合作者开发了改进的重建技术，并负责维护STACEE光学系统。CWRU的小组还参与了皮埃尔·奥格天文台（Pierre Auger Observatory）的一个有限但重要的任务，这是一个探测最高能量宇宙射线的主要国际实验。AUGER是一个混合探测器，由1600个水切伦科夫地面站和5个相关的荧光探测器组成。每个地面站的一个关键部件是GPS时钟，用于标记阵雨粒子到达地面的时间。CWRU小组负责校准将在AUGER中使用的1600个GPS单元中的每一个，以将事件的时间戳定在20秒的绝对时间内。这项工作可能会对粒子天体物理学以外的几个领域产生更广泛的影响。这包括(1)利用定日镜支持地球观测卫星的遥感；(2)设计和应用新型非成像光学系统；(3)开发用于太阳能应用的镜面测量技术；(4)开发用于高速数据采集的软件。

This proposal requests funds to support the Case Western Reserve University (CWRU) group to work on two astrophysics experiments. STACEE is a new detector for ground-based gamma-ray astronomy in the energy range 50 to 1000 GeV, corresponding to an energy regime that has been inaccessible to previous ground-based experiments. STACEE is located at the National Solar Thermal Test Facility (NSTTF) in Albuquerque, NM at Sandia National Laboratories and uses large heliostat mirrors at the NSTTF to collect Cherenkov light from gamma-ray air showers. Construction of the STACEE experiment is now complete, but during construction two major observing campaigns were conducted. In 1998, STACEE detected the Crab nebula with a significance in excess of six standard deviations. During the summer of 2001, STACEE detected the extra-galactic source Markarian 421 during an outburst. Over the next three years, STACEE will observe active galactic nuclei (AGN), gamma-ray bursters (GRB) and several other galactic and extra-galactic objects. With a low energy threshold, many more extra-galactic sources will be visible to STACEE that are unobservable at higher energies due to intergalactic gamma-gamma absorption. STACEE is perhaps uniquely capable of making extended observations of sources in the energy range from 50 to 250 GeV. Collaborators from CWRU have developed improved reconstruction techniques and are responsible for maintaining the STACEE optical system. The group at CWRU is also participating in a limited, but important, role in the Pierre Auger Observatory, a major international experiment to detect the highest energy cosmic rays. AUGER is a hybrid detector made of 1600 water-Cherenkov ground stations and five associated fluorescence detectors. A critical component of each ground station is the GPS clock used to time-tag the arrival of shower particles on the ground. The CWRU group is responsible for calibrating each of the 1600 GPS units that will be used in AUGER to timestamp events to within 20 ns absolute time. This work has a potential broader impact on several areas outside of particle astrophysics. These include (1) the use of heliostats to support remote sensing by earth-viewing satellites, (2) the design and application of new types of non-imaging optical systems, (3) the development of mirror measurement techniques for solar energy applications, and (4) the development of software for high-speed data acquisition.