13932374
Design and Construction of the Mini-Calorimeter of the AGILE Satellite
Abstract AGILE is a small space mission of the Italian Space Agency (ASI) devoted to gamma-ray and hard-X astrophysics, successfully launched on April 23, 2007. The AGILE Payload is composed of three instruments: a gamma-ray imager based on a tungsten-silicon tracker (ST), for observations in the gamma ray energy range 30 MeV–50 GeV, a Silicon based X-ray detector, SuperAGILE (SA), for imaging in the range 18–60 keV and a CsI(Tl) Mini-Calorimeter (MCAL) that detects gamma rays or charged particles energy loss in the range 300 keV–100 MeV. MCAL is composed of 30 CsI(Tl) scintillator bars with photodiode readout at both ends, arranged in two orthogonal layers. MCAL can work both as a slave of the ST and as an independent gamma-ray detector for transients and gamma-ray bursts detection. In this paper a detailed description of MCAL is presented together with its performance.
119196535
Evaluating the maximum likelihood method for detecting short-term variability of AGILE γ-ray sources
Context. The AGILE space mission (whose instrument is sensitive to the energy ranges 18–60 keV, and 30 MeV–50 GeV) has been operating since 2007. Assessing the statistical significance of the time variability of γ-ray sources above 100 MeV is a primary task of the AGILE data analysis. In particular, it is important to verify the instrument sensitivity in terms of Poisson modeling of the data background, and to determine the post-trial confidence of detections. Aims. The goals of this work are: (i) to evaluate the distributions of the likelihood ratio test for both “empty” fields and regions of the Galactic plane, and (ii) to calculate the probability of false detections over multiple time intervals. Methods. We describe in detail the techniques used to search for short-term variability in the AGILE γ-ray source database. We describe the binned maximum likelihood method used for the analysis of AGILE data, and the numerical simulations that support the characterization of the statistical analysis. We apply our method to both Galactic and extragalactic transients, and provide a few examples. Results. After checking the reliability of the statistical description tested with the real AGILE data, we obtain the distribution of p-values for blind and specific source searches. We apply our results to the determination of the post-trial statistical significance of detections of transient γ-ray sources in terms of pre-trial values. Conclusions. The results of our analysis allow a precise determination of the post-trial significance of γ-ray sources detected by AGILE.
107972078
The Test Equipment of the AGILE Minicalorimeter Prototype
AGILE is an ASI (Italian Space Agency) Small Space Mission for high energy astrophysics in the range 30 MeV – 50 GeV. The AGILE satellite is currently in the C phase and is planned to be launched in 2005. The Payload shall consist of a Tungsten‐Silicon Tracker, a CsI Minicalorimeter, an anticoincidence system and a X‐Ray detector sensitive in the 10–40 KeV range. The purpose of the Minicalorimeter (MCAL) is twofold. It shall work in conjunction with the Tracker in order to evaluate the energy of the interacting photons, and it shall operate autonomously in the energy range 250KeV–250 MeV for detection of transients and gamma ray burst events and for the measurement of gamma ray background fluctuations. We present the architecture of the Test Equipment we have designed and developed in order to test and verify the MCAL Simplified Electrical Model prototype which has been manufactured in order to validate the design of the MCAL Proto Flight Model.
121974449
The mini-calorimeter for the AGILE satellite
AGILE is a small space mission of the Italian Space Agency (ASI) devoted to observations for astrophysics in the gamma-ray energy range 30 MeV-50 GeV with a simultaneous window in the X-ray band 10 keV-40 keV. AGILE payload is made of a tungsten-silicon tracker, a CsI mini-calorimeter for the high energy band and a silicon based X-ray detector (SuperAgile); an anticoincidence system carries out background rejection. In the gamma-ray's band the satellite will have a field of view of about 1/5 of the sky, with angular resolution of a few arc-minutes and good timing resolution. For the high energy AGILE detection principle is based on the pair production process that arises from the interaction between photons and the tungsten layers above the silicon tracker. The silicon tracker is designed to determine the direction of the incoming radiation, while the mini-calorimeter evaluates the energy of the interacting photons and particles. For the detection of transients and gamma-ray burst events, the mini-calorimeter will also work as a stand-alone gamma-ray detector, with no imaging capabilities, covering the energy range 250 keV-250 MeV. The mini-calorimeter is made of an array of position sensitive CsI(Tl) scintillator bars with photodiode read-out. The characteristics of its detector elements and the front end electronics signal processing allow a moderate position reconstruction of the detected event. In this paper a description of the mini-calorimeter is reported as well as a summary of performances reached with the pre-flight instrument models already built and tested.
118532651
AGILE Observations of Terrestrial Gamma-Ray Flashes
The AGILE satellite, operating since mid 2007 and primarily devoted to high-energy astrophysics,is one of the only three currently operating space instruments capable of detecting TerrestrialGamma-Ray Flashes (TGFs), together with RHESSI and Fermi-GBM. Thanks to the AGILEMini-Calorimeter instrument energy range extended up to 100MeV and its ﬂexible trigger logic onsub-millisecond time scales, AGILE is detecting more than 10 TGFs/month, adding a wealth ofobservations which pose severe constrains on production models. The main AGILE discoveries inTGF science during two and a half years of observations are the following: 1) the TGF spectrumextends well above 40 MeV, 2) the high energy tail of the TGF spectrum is harder than expectedand cannot be easily explained by previous theoretical models, 3) TGFs can be localized from spaceusing high-energy photons detected by the AGILE gamma-ray imaging detector. In this presenta-tion we will describe the characteristics of the 2.5-years AGILE TGF sample, focusing on the recentresults concerning the TGF high-energy spectral characteristics.I. INTRODUCTION
122049535
Search of GRB with AGILE Minicalorimeter
Abstract AGILE, the small scientific mission of the Italian Space Agency devoted to Hard-X and Gamma-ray astrophysics, was successfully launched on April 23, 2007. The AGILE payload is composed of a tungsten-silicon tracker (ST), operating in the gamma-ray energy range 30 MeV–50 GeV; Super-AGILE, an X-ray imager operating in the energy range 15–45 keV; the Minicalorimeter (MCAL) and an Anticoincidence shield. MCAL is a detector of about 1400 cm 2 sensitive in the range 0.3–200 MeV, that can be used both as a slave of the ST to contribute to the AGILE Gamma Ray imaging Detector (GRID operative mode) and autonomously for detection of transient events (BURST operative mode). MCAL is made of 30 CsI(Tl) bar-shaped scintillation detectors with photodiode readout at both ends, arranged in two orthogonal layers. Energy and position of interaction can be derived from a proper composition of the signals readout at the bar's ends, absolute time tagging can be achieved with a μ s resolution. The Burst logic deals with various rate-meters on different time scales, energy bands, and MCAL spatial zones. Different algorithms can be chosen for Burst triggering considering also the contribution of other detectors like Super AGILE. In this paper the various trigger logic will be reviewed as well as their on-ground test performed with a dedicated experimental setup.
126272154
Tagging of low-pt electrons from b decays with the ATLAS electromagnetic calorimeter
125535688
Cosmic Ray, Beam-Halo and Beam-Gas Rate Studies for ATLAS Commissioning
124629008
Comparison of the ATLAS and CMS discovery potential for the H -> gamma gamma channel at the LHC
118222129
Final Report of the Simulation Optimization Task Force
This is the final report of the ATLAS Simulation Optimization Task Force, establishedin June of 2007. This note justifies the selected Geant4 version, physics list, and range cuts to be used by the default ATLAS simulation for initial data taking and beyond. The current status of several projects, including detector description, simulation validation, studies of additional Geant4 parameters, and cavern background, are reported.
123721381
MINIMAL SUPERSYMMETRIC STANDARD MODEL HIGGS RATES AND BACKGROUNDS IN ATLAS
This study presents an overview of the potential of the ATLAS detector at LHC for the observation of the Higgs boson of the minimal supersymmetric Standard Model (MSSM). The expected rates, backgrounds and significances are discussed channel by channel using realistic assumptions for the detector performance. As final results, the ranges of the MSSM parameter space projected on the (mA, tanβ) and (mh, tanβ) planes, for which the expected significances for the discovery of the different channels exceed a 5σ value, are shown for the ATLAS detector alone and for combined results from the ATLAS and CMS detectors. It is concluded that the combined potential of the two LHC detectors should fully cover the Higgs sector of the MSSM parameter space. The sensitivity of the results to the upper limit of the allowed mass for the lightest Higgs boson is extensively discussed. The direct impact of the SUSY particle sector on such searches is neglected in this paper.