A method to localize gamma-ray bursts using POLAR

Article Article scientifique Article A method to localize gamma-ray bursts using POLAR eng 2010 author Suarez Garcia Estela 651443 author Haas Daniel 23589 author Hajdas W. author Lamanna G. author Leluc Catherine 25272 author Marcinkowski R. author Mtchedlishvili A. author Orsi Silvio 668847 author Pohl Martin 96464 author Produit Nicolas 0000-0001-7138-7677 22959 author Rapin Divic Jean 24725 author Rybka D. author Vialle J.-P. 624-634 10.1016/j.nima.2010.10.006 0168-9002 http://linkinghub.elsevier.com/retrieve/pii/S0168900210022357 The hard X-ray polarimeter POLAR aims to measure the linear polarization of the 50–500 keV photons arriving from the prompt emission of γ-ray bursts (GRBs). The position in the sky of the detected GRBs is needed to determine their level of polarization. We present here a method by which, despite of the polarimeter incapability of taking images, GRBs can be roughly localized using POLAR alone. For this purpose scalers are attached to the output of the 25 multi-anode photomultipliers (MAPMs) that collect the light from the POLAR scintillator target. Each scaler measures how many GRB photons produce at least one energy deposition above 50 keV in the corresponding MAPM. Simulations show that the relative outputs of the 25 scalers depend on the GRB position. A database of very strong GRBs simulated at 10 201 positions has been produced. When a GRB is detected, its location is calculated searching the minimum of the χ2χ2 obtained in the comparison between the measured scaler pattern and the database. This GRB localization technique brings enough accuracy so that the error transmitted to the 100% modulation factor is kept below 10% for GRBs with fluence Ftot≥10−5ergcm−2. The POLAR localization capability will be useful for those cases where no other instruments are simultaneously observing the same field of view. Gamma-ray burst Source localization Polarization POLAR Dewey 500.2 Dewey 520 26 Département d'astronomie 12 34 Département de physique nucléaire et corpusculaire 132 false Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment 624 3 7d510753-7208-4fef-9329-adbe296434cd Article (Published version) Restricted Pohl24.pdf 827347 application/pdf restrictedAccess Faculté des sciences / Département d'astronomie Faculté des sciences / Section de physique / Département de physique nucléaire et corpusculaire

Title	Published in	Year	Views	Downloads

A method to localize gamma-ray bursts using POLAR	Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment	2010	679	0
X-Ray polarization: RHESSI results and POLAR prospects		2010	1,144	202

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Suarez Garcia, Estela