Energy calibration of GTM on ground
Abstract
The Gamma-ray Transients Monitor (GTM) on board the Formosat-8B (FS-8B) satellite is designed to detect and localize Gamma-Ray Bursts (GRBs). By utilizing 2+2 CITIROC chips to manipulate 4+4 detectors, which are composed of GAGG(Ce) scintillators coupled with Silicon Photomultipliers (SiPMs) and oriented in various directions to achieve all-sky coverage, the GRB saturation fluences of GTM in the 50 keV to 1 MeV range for Short GRBs (SGRBs) and Long GRBs (LGRBs) were estimated to be about and , respectively, based on simulations. To precisely interpret the GTM readout signal in terms of energy, several measurements for isotope and gain calibration were conducted. Despite encountering issues with crosstalk and SiPM saturation effect in the data, the energy spectrum can still be recovered by appropriately discarding channel noise and mapping with the correct ADC-to-energy relation. This paper summarizes the energy resolution of GTM and the linear variations in the relationship between photon energy and readout signal. At 662 keV, the energy resolution is about 16 %. Also, it demonstrates that greater gain is achieved by increasing voltage or decreasing temperature.
Cite
@article{arxiv.2410.04827,
title = {Energy calibration of GTM on ground},
author = {Chien-You Huang and Hsiang-Kuang Chang and Chih-Hsun Lin and Che-Chih Tsao and Chin-Ping Hu and Hao-Min Chang and Yan-Fu Chen and An-Hsuan Feng and Yi-Wen Huang and Tzu-Hsuan Lin and Yi-Ning Tsao and Chih-En Wu and Chun-Wei Wu},
journal= {arXiv preprint arXiv:2410.04827},
year = {2024}
}