THE LARGE AREA TELESCOPE ON THE FERMI GAMMA-RAY SPACE TELESCOPE MISSION
THE LARGE AREA TELESCOPE ON THE FERMI GAMMA-RAY SPACE TELESCOPE MISSION
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DOI：
10.1088/0004-637x/697/2/1071
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发表时间：
2009-06-01
影响因子：
4.9
通讯作者：
Ziegler, M.
中科院分区：
文献类型：
--
作者：
Atwood, W. B.;Abdo, A. A.;Ziegler, M.
大面积望远镜（英语：Large Area Telescope，缩写为LAT）是费米伽马射线太空望远镜（英语：Fermi Gamma-ray Space Telescope，缩写为Fermi）使命的主要仪器，是一个成像、宽视场、高能伽马射线望远镜，涵盖能量范围从20 MeV以下到300 GeV以上。LAT是由国际合作建造的，来自法国、意大利、日本、瑞典和美国的空间机构、高能粒子物理研究所和大学的贡献。本文介绍了LAT，其飞行前的预期性能，并总结了关键的科学目标，将解决。在轨性能将在随后的一篇论文中详细介绍。LAT是一个具有精密跟踪器和热量计的对转换望远镜，每个都由16个模块的4x 4阵列，覆盖跟踪器阵列的分段反符合探测器以及可编程触发器和数据采集系统组成。每个跟踪器模块具有18（x，y）个跟踪平面的垂直堆叠，每个托盘包括两层（x和y）单面硅条探测器和高Z转换器材料（钨）。每个量热计模块有96 CsI（Tl）晶体，安排在一个八层hodoscopic配置与8.6辐射长度的总深度，给出了纵向和横向的能量沉积模式的信息。量热计的深度和分段使LAT的高能量范围成为可能，并显著有助于背景抑制。跟踪器的纵横比（高/宽）为0.4，允许大的FoV（2.4 sr），并确保跟踪器中启动的大多数对转换簇射将进入热量计进行能量测量。LAT获得的数据旨在（1）允许快速通知高能伽马射线爆发和瞬变，并促进对可变源的监测，（2）产生从全天巡天获得的数千个高能源的广泛目录，（3）测量数百个源的20 MeV到50 GeV以上的光谱，（4）将点源定位到0.3-2弧分，（5）绘制并获得扩展源的光谱，如SNR，分子云和附近的星系，（6）测量弥散各向同性伽马射线背景，直到TeV能量，（7）探索暗物质的发现空间。
The Large Area Telescope (Fermi/LAT, hereafter LAT), the primary instrument on the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view (FoV), high-energy gamma-ray telescope, covering the energy range from below 20 MeV to more than 300 GeV. The LAT was built by an international collaboration with contributions from space agencies, high-energy particle physics institutes, and universities in France, Italy, Japan, Sweden, and the United States. This paper describes the LAT, its preflight expected performance, and summarizes the key science objectives that will be addressed. On-orbit performance will be presented in detail in a subsequent paper. The LAT is a pair-conversion telescope with a precision tracker and calorimeter, each consisting of a 4 x 4 array of 16 modules, a segmented anticoincidence detector that covers the tracker array, and a programmable trigger and data acquisition system. Each tracker module has a vertical stack of 18 (x, y) tracking planes, including two layers (x and y) of single-sided silicon strip detectors and high-Z converter material (tungsten) per tray. Every calorimeter module has 96 CsI(Tl) crystals, arranged in an eight-layer hodoscopic configuration with a total depth of 8.6 radiation lengths, giving both longitudinal and transverse information about the energy deposition pattern. The calorimeter's depth and segmentation enable the high-energy reach of the LAT and contribute significantly to background rejection. The aspect ratio of the tracker (height/width) is 0.4, allowing a large FoV (2.4 sr) and ensuring that most pair-conversion showers initiated in the tracker will pass into the calorimeter for energy measurement. Data obtained with the LAT are intended to (1) permit rapid notification of high-energy gamma-ray bursts and transients and facilitate monitoring of variable sources, (2) yield an extensive catalog of several thousand high-energy sources obtained from an all-sky survey, (3) measure spectra from 20 MeV to more than 50 GeV for several hundred sources, (4) localize point sources to 0.3-2 arcmin, (5) map and obtain spectra of extended sources such as SNRs, molecular clouds, and nearby galaxies, (6) measure the diffuse isotropic gamma-ray background up to TeV energies, and (7) explore the discovery space for dark matter.