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- Atwood, W. B., et al.
(author)
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THE LARGE AREA TELESCOPE ON THE FERMI GAMMA-RAY SPACE TELESCOPE MISSION
- 2009
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 697:2, s. 1071-1102
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Journal article (peer-reviewed)abstract
- 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.
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| 3. |
- Settimi, Laura, et al.
(author)
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Cancer risk among female agricultural workers : a multi-center case-control study
- 1999
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In: American Journal of Industrial Medicine. - 0271-3586 .- 1097-0274. ; 36:1, s. 135-141
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Journal article (peer-reviewed)abstract
- BackgroundCancer risk among women engaged in farming has been poorly investigated. This group of female workers is of particular interest, however, since they may experience exposure to several potential agricultural hazards.MethodsA hospital-based case-control study was conducted in five Italian rural areas to examine the association between cancer and farming among women. The areas selected were located in three different regions (i.e., Piedmont, Tuscany, and Emilia-Romagna). The following cancer sites were selected for the study: stomach, colon, rectum, lung, skin melanoma, skin non-melanoma, breast, cervix and corpus uteri, ovary, bladder, kidney. Cases of non-Hodgkin's lymphoma were also included. Altogether, 1,044 newly diagnosed cases aged 20–75 years were ascertained from hospital records from March 1990 to September 1992, and for 945 of them detailed information was collected by a standard questionnaire. The analyses of data were performed comparing each case series to a reference group drawn from among the other sites. Unconditional logistic regression models were used in the statistical analyses.ResultsStatistically significant increased risks in association with farming were estimated for skin melanoma (OR 2.7, 95% CI 1.2–5.8) and bladder cancer (OR 2.7, 95% CI 1.2–6.1). Lung cancer was also found increased but not at a statistically significant level (OR 1.7, 95% CI 0.7–4.4). An OR lower than unity was observed for postmenopausal breast cancer (OR 0.4, 95% CI 0.3–0.7).ConclusionsThe present study suggests that women in farming might experience increased risk of cancers, not usually found in excess among male farmers, as well as a protective effect for postmenopausal breast cancer. The role of different patterns of exposure or gender specific responses should be considered in further studies.
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