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Triggers and alerts with GLAST  [PDF]
J. Cohen-Tanugi,N. Omodei,F. Longo,S. Bansal,J. Bonnell,J. P. Norris,J. D. Scargle,R. Preece,R. M. Kippen
Physics , 2003,
Abstract: We present preliminary results on Gamma Ray Burst (GRB) triggers with the Gamma-ray Large Area Space Telescope (GLAST). After a brief summary of the detector layout, GLAST expected performances on GRB detection are recalled. Status report on the simulation software and preliminary triggers studies are then reported, already showing significant improvement on EGRET results.
GLAST, GRBs, and Quantum Gravity  [PDF]
J. P. Norris,J. T. Bonnell,G. F. Marani,J. D. Scargle
Physics , 1999,
Abstract: The fast temporal structures and cosmological distances of gamma-ray bursts (GRBs) afford a natural laboratory for testing theories of frequency-dependent propagation of high-energy photons, as predicted for quantum gravity (QG). We calibrate the sensitivity of the proposed Gamma-ray Large Area Space Telescope (GLAST) by performing simulations which include: the response of GLAST to a GRB fluence distribution; a distribution of spectral power-law indices similar to the EGRET sample; and consideration of gamma-gamma attenuation, significant above ~ 10 GeV for redshifts z > 3 - 5. We find that GLAST should detect > 200 GRBs per year, with sensitivity to a few tens of GeV for a few bursts. GLAST could detect the energy- and distance-dependent dispersion (10 ms / GeV / Gpc) predicted by QG with 1 - 2 years of observations. Attribution to QG would require correlation of GRB redshifts with the temporal and energetic signatures.
The Use of HepRep in GLAST  [PDF]
J. Perl,R. Giannitrapani,M. Frailis
Computer Science , 2003,
Abstract: HepRep is a generic, hierarchical format for description of graphics representables that can be augmented by physics information and relational properties. It was developed for high energy physics event display applications and is especially suited to client/server or component frameworks. The GLAST experiment, an international effort led by NASA for a gamma-ray telescope to launch in 2006, chose HepRep to provide a flexible, extensible and maintainable framework for their event display without tying their users to any one graphics application. To support HepRep in their GUADI infrastructure, GLAST developed a HepRep filler and builder architecture. The architecture hides the details of XML and CORBA in a set of base and helper classes allowing physics experts to focus on what data they want to represent. GLAST has two GAUDI services: HepRepSvc, which registers HepRep fillers in a global registry and allows the HepRep to be exported to XML, and CorbaSvc, which allows the HepRep to be published through a CORBA interface and which allows the client application to feed commands back to GAUDI (such as start next event, or run some GAUDI algorithm). GLAST's HepRep solution gives users a choice of client applications, WIRED (written in Java) or FRED (written in C++ and Ruby), and leaves them free to move to any future HepRep-compliant event display.
GLAST Dark Matter Search  [PDF]
Lawrence Wai
Physics , 2002,
Abstract: The GLAST Large Area Telescope, scheduled for launch in 2006, is a next generation space based gamma ray telescope which will improve in point source sensitivity by a factor of 30 over that of EGRET below 10 GeV, and extend beyond EGRET up to 300 GeV. Thus GLAST offers a unique opportunity to discover WIMP dark matter through precision studies of gamma rays produced in pair annihilations. The most dense region of dark matter in our galaxy is currently thought to occur at the center; in particular, dark matter should concentrate within 3 pc of the putative supermassive black hole located at the SgrA* radio source. In fact, the 2nd and 3rd EGRET catalogs contain a significant point source coincident with the Milky Way galactic center within a resolution of 12 arcminutes. The EGRET team has determined that the spectral and temporal characteristics of this point source are consistent with dark matter WIMP annihilations. More detailed analysis has determined that the magnitude and spectrum of the EGRET source is consistent with relic WIMPs concentrated within 3 pc of the central supermassive black hole. Furthermore, the SgrA* radio emission is consistent with the synchrotron radiation expected from electrons and positrons produced in WIMP annihilations. If true, then GLAST should be able to constrain the particle properties of the postulated WIMP with 1 month of data.
Calibration Infrastructure for the GLAST LAT  [PDF]
J. Bogart
Physics , 2003,
Abstract: The GLAST LAT calibration infrastructure is designed to accommodate a wide range of time-varying data types, including at a minimum hardware status bits, conversion constants, and alignment for the GLAST LAT instrument and its prototypes. The system will support persistent XML and ROOT data to begin with; other physical formats will be added if necessary. In addition to the "bulk data", each data set will have associated with it a row in a rdbms table containing metadata, such as timestamps, data format, pointer to the location of the bulk data, etc., which will be used to identify and locate the appropriate data set for a particular application. As GLAST uses the Gaudi framework for event processing, the Calibration Infrastructure makes use of several Gaudi elements and concepts, such as conversion services, converters and data objects and implements the prescribed Gaudi interfaces (IDetDataSvc, IValidity, ..). This insures that calibration data will always be valid and appropriate for the event being processed. The persistent representation of a calibration dataset as two physical pieces in different formats complicates the conversion process somewhat: two cooperating conversion services are involved in the conversion of any single dataset.
Anticoincidence Detector for GLAST  [PDF]
A. Moiseev,J. Norris,J. Ormes,S. Ritz,D. Thompson
Physics , 1999,
Abstract: The Gamma-ray Large Area Space Telescope (GLAST) is now being designed by a number of collaborating institutions. It will study the cosmic gamma radiation from 20 MeV to 300 GeV with high precision and sensitivity, greatly expanding on the important EGRET results. One of the key systems of the instrument, the Anticoincidence Detector (ACD), is designed to reject the majority of charged particles, which are the background for any gamma-ray experiment. The ACD of EGRET has suffered from the self-veto effect when the products of the high energy photon interactions in the instrument's calorimeter cause a veto signal in the anticoincidence detector (backsplash effect), resulting in the degradation of the efficiency for high energy (> 5 GeV) gamma rays. To avoid this effect, the ACD for GLAST is divided into many scintillating tiles with wave-shifting fiber readout. The design of this detector along with the beam test and simulation results are given in this paper.
The GLAST Burst Monitor (GBM)  [PDF]
G. G. Lichti,M. S. Briggs,R. Diehl,G. Fishman,R. Georgii,R. M. Kippen,C. Kouveliotou,C. Meegan,W. Paciesas,R. Preece,V. Schoenfelder,A. von Kienlin
Physics , 2001,
Abstract: The selection of the GLAST burst monitor (GBM) by NASA will allow the investigation of the relation between the keV and the MeV-GeV emission from gamma-ray bursts. The GBM consists of 12 NaI and 2 BGO crystals allowing a continuous measurement of the energy spectra of gamma-ray bursts from ~5 keV to \~30 MeV. One feature of the GBM is its high time resolution for time-resolved gamma-ray spectroscopy. Moreover the arrangement of the NaI crystals allows a rapid on-board location (<15 degrees) of a gamma-ray burst within a FoV of ~8.6 sr. This position will be communicated to the main instrument of GLAST making follow-up observations at high energies possible.
Supersymmetric Dark Matter with GLAST  [PDF]
Andrea Lionetto
Physics , 2003,
Abstract: We present a short review of the status of the dark matter problem. In particular we show that one of the best motivated candidate for the dark matter is the neutralino, a supersymmetric particle. Finally we study the possibility to detect gamma rays coming from neutralino pair annihilations that take place in our Galactic Center with the upcoming satellite detector GLAST.
XML for Detector Description at GLAST  [PDF]
J. R. Bogart,D. Favretto,R. Giannitrapani
Physics , 2002,
Abstract: The problem of representing a detector in a form which is accessible to a variety of applications, allows retrieval of information in ways which are natural to those applications, and is maintainable has been vexing physicists for some time. Although invented to address an entirely different problem domain, the document markup meta-language XML is well-suited to detector description. This paper describes its use for a GLAST detector.
Search for Dark Matter with GLAST  [PDF]
Aldo Morselli,Andrea Lionetto,Alessandro Cesarini,Francesco Fucito,Piero Ullio
Physics , 2002, DOI: 10.1016/S0920-5632(02)01844-3
Abstract: The detection of exotic cosmic rays due to pair annihilation of dark matter particles in the Milky Way halo is a viable techniques to search for supersymmetric dark matter candidates. The study of the spectrum of gamma-rays, antiprotons and positrons offers good possibilities to perform this search in a significant portion of the Minimal Supersymmetric Standard Model parameter space. In particular the EGRET team have seen a convincing signal for a strong excess of emission from the Galactic center that has no simple explanation with standard processes. We will review the limits achievable with the experiment GLAST taking into accounts the LEP results and we will compare this method with the antiproton and positrons experiments.
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