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تسجيل مستخدم جديدCalibration of Gamma-ray Burst Polarimeter POLAR
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Gamma Ray Bursts (GRBs) are the strongest explosions in the universe which might be associated with creation of black holes. Magnetic field structure and burst dynamics may influence polarization of the emitted gamma-rays. Precise polarization detection can be an ultimate tool to unveil the true GRB mechanism. POLAR is a space-borne Compton scattering detector for precise measurements of the GRB polarization. It consists of a 40$times$40 array of plastic scintillator bars read out by 25 multi-anode PMTs (MaPMTs). It is scheduled to be launched into space in 2016 onboard of the Chinese space laboratory TG2. We present a dedicated methodology for POLAR calibration and some calibration results based on the combined use of the laboratory radioactive sources and polarized X-ray beams from the European Synchrotron Radiation Facility. They include calibration of the energy response, computation of the energy conversion factor vs. high voltage as well as determination of the threshold values, crosstalk contributions and polarization modulation factors.
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As a space-borne detector POLAR is designed to conduct hard X-ray polarization measurements of gamma-ray bursts on the statistically significant sample of events and with an unprecedented accuracy. During its development phase a number of tests, cali
brations runs and verification measurements were carried out in order to validate instrument functionality and optimize operational parameters. In this article we present results on gain optimization togeter with verification data obtained in the course of broad laboratory and environmental tests. In particular we focus on exposures to the $^{137}$Cs radioactive source and determination of the gain dependence on the high voltage for all 1600 detection channels of the polarimeter. Performance of the instrument is described in detail with respect to the dynamic range, energy resolution and temperature dependence. Gain optimization algorithms and response non-uniformity studies are also broadly discussed. Results presented below constitute important parts for development of the POLAR calibration and operation database.
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SPHiNX is a proposed gamma-ray burst (GRB) polarimeter mission operating in the energy range 50-600 keV with the aim of studying the prompt emission phase. The polarisation sensitivity of SPHiNX reduces as the uncertainty on the GRB sky position incr
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SPHiNX is a proposed satellite-borne gamma-ray burst polarimeter operating in the energy range 50-500 keV. The mission aims to probe the fundamental mechanism responsible for gamma-ray burst prompt emission through polarisation measurements. Optimisi
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