{"work":{"id":"fabe2f87-380f-4f82-aafa-bad10d9fbcf0","openalex_id":null,"doi":null,"arxiv_id":"0902.1089","raw_key":null,"title":"The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission","authors":null,"authors_text":"Fermi-LAT collaboration, The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission, Astrophys","year":2009,"venue":"astro-ph.IM","abstract":"(Abridged) 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, high-energy gamma-ray telescope, covering the energy range from below 20 MeV to more than 300 GeV. This paper describes the LAT, its pre-flight 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 4x4 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 8 layer hodoscopic configuration with a total depth of 8.6 radiation lengths. The aspect ratio of the tracker (height/width) is 0.4 allowing a large field-of-view (2.4 sr). Data obtained with the LAT are intended to (i) permit rapid notification of high-energy gamma-ray bursts (GRBs) and transients and facilitate monitoring of variable sources, (ii) yield an extensive catalog of several thousand high-energy sources obtained from an all-sky survey, (iii) measure spectra from 20 MeV to more than 50 GeV for several hundred sources, (iv) localize point sources to 0.3 - 2 arc minutes, (v) map and obtain spectra of extended sources such as SNRs, molecular clouds, and nearby galaxies, (vi) measure the diffuse isotropic gamma-ray background up to TeV energies, and (vii) explore the discovery space for dark matter.","external_url":"https://arxiv.org/abs/0902.1089","cited_by_count":null,"metadata_source":"pith","metadata_fetched_at":"2026-05-25T14:15:56.124713+00:00","pith_arxiv_id":"0902.1089","created_at":"2026-05-10T07:52:13.938349+00:00","updated_at":"2026-05-25T14:15:56.124713+00:00","title_quality_ok":true,"display_title":"Atwood, A.A","render_title":"Atwood, A.A"},"hub":{"state":{"work_id":"fabe2f87-380f-4f82-aafa-bad10d9fbcf0","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":14,"external_cited_by_count":null,"distinct_field_count":4,"first_pith_cited_at":"2019-06-27T18:47:22+00:00","last_pith_cited_at":"2026-05-21T07:45:54+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-05-28T17:38:53.540896+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":5},{"context_role":"dataset","n":1}],"polarity_counts":[{"context_polarity":"background","n":5},{"context_polarity":"use_dataset","n":1}],"runs":{},"summary":{},"graph":{},"authors":[]}}