121426765
The mini-calorimeter detector for the AGILE mission
AGILE is an ASI space mission for high energy astrophysics in the gamma ray energy range 30MeV-50GeV, and in the X-ray band (10keV-40keV). AGILE is composed of three detecting systems: a Tungsten-Silicon Tracker, a Csl Mini-Calorimeter and a Silicon based X-ray detector (Super-Agile), plus an anticoincidence system for background rejection. The satellite will have good imaging performances (with angular resolution of a few arc-minutes in the gamma ray band), good timing resolution and a large field of view (about 1/5 of the sky). AGILE high energy detector is composed of a Silicon Tracker, a Mini-Calorimeter, the Anticoincidence and the Data Handling system The Mini-Calorimeter can also work as a stand-alone gamma ray detector in the energy range 250keV-250MeV, with no imaging capabilities, for the detection of transients and gamma ray burst events and for the evaluation of gamma ray background fluctuations. The Mini-Calorimeter is made of 30 independent elements of 37.5 × 2.3 × 1.5  cm stacked in two layers. Each detector scintillator signal is read out via two photodiodes glued on the small surfaces of the bar. The characteristics of the engineering model detectors has been deeply investigated and will be reported.
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.
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.
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.
109815200
Test campaign of the mini-calorimeter for the AGILE satellite
The AGILE Mini-Calorimeter (MCAL, with total on-axis radiation length 1.5 X0) comprises 2 orthogonal planes each consisting of 16 CsI(Tl) bars. Its primary purpose is the energy determination of gamma-rays detected by the Gamma-Ray Imaging Detector (GRID) Tracker (energy range 30 MeV–50 GeV). In addition, the MCAL is capable of independently triggering and detecting gamma-ray bursts and other impulsive events in the energy range 0.25–250 MeV. A MCAL prototype, comprising 8 CsI(Tl) detector elements, was tested both with laboratory sources and with charged particles (p=1 GeV/c) during an AGILE Beam Test carried out in November 2000 at the CERN T11 beamline (East Hall, CERN PS). The test setup included a prototype of the electronic chain. A prototype of the digital data acquisition chain, which will be the baseline of the payload Electronic Ground Support Equipment, was also built and tested. We present the preliminary results of this test campaign dedicated to characterizing the detector unit and electronics.
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
14248170
Impact of energy and luminosity upgrades at LHC on the physics programme of ATLAS
The impact of possible LHC upgrades on the physics capabilities of the ATLAS detector is discussed. As a benchmark, an increase in the luminosity by a factor of 10 is considered. For comparison, the doubling of the LHC energy is also explored. Both upgrades significantly enhance the physics capabilities of ATLAS. Measured in terms of the mass reach for new particles, the energy upgrade is more powerful. However, in cases where the effect of an upgrade is to increase the precision of measurements as a result of larger data samples, the luminosity upgrade can be at least as powerful. The pile-up of minimum bias events at higher luminosity could limit the physics performance of ATLAS in areas where tagging of forward jets is needed.
125535688
Cosmic Ray, Beam-Halo and Beam-Gas Rate Studies for ATLAS Commissioning
126272154
Tagging of low-pt electrons from b decays with the ATLAS electromagnetic calorimeter
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.
16422857
Preparing for LHC data-taking with the ATLAS experiment
The status of the ATLAS experiment a few months before the start-up of LHC operation is described. Emphasis is given to the preparation for the imminent data-taking phase through commissioning studies with cosmics data. A few examples of the physics potential and goals with early LHC data are also presented.