伽瑪射線瞬變事件監測儀（GTM）是福衛八號第二枚衛星（FS-8B）上的次要籌載，該衛星由國家太空中心（TASA）開發，計畫於2026年發射。GTM的目標是偵測和定位伽瑪射線爆（GRBs）。GTM由位於FS-8B兩側的兩個相同模組組成。每個模組使用2個CITIROC晶片來操作4個探測器，這些探測器由GAGG(Ce)閃爍體與矽光電倍增管（SiPMs）耦合組成，並且以不同方向排列以實現全天空覆蓋。

本論文內容可分為兩部分。在第一部分，根據模擬得知GTM的探測效率在GRB輻射通量（能量範圍從10 keV到1 MeV）大於6e-7和2e-6 erg/cm^2時，對短伽瑪射線爆（SGRBs）和長伽瑪射線爆（LGRBs）分別超過50%。因此，依據Fermi/GBM十年來觀測到的GRB輻射通量分佈和GTM 36%的工作週期，預計GTM每年可偵測到約50個GRB。關於定位能力，對於GRB輻射通量為4e-6和4e-5 erg/cm^2的LGRBs，99.7%信水準下的定位不確定度分別約為30和3度。

在第二部分，考量CITIROC晶片的死區時間，估算出SGRBs和LGRBs的GRB飽和輻射通量分別約為3.1e-4和5.0e-3 erg/cm^2。此外，為了詮釋GTM的讀出訊號與能量之間的關係，進行了若干校準測量。儘管在數據中遇到閃爍光分光和SiPM飽和效應的問題，測量的能譜仍可以被恢復。在662 keV，GTM的能量解析度約為15%。光子能量與讀出訊號之間關係的線性變化表明，透過增加電壓或降低溫度可以獲得更大的增益。

The Gamma-ray Transients Monitor (GTM) is a secondary payload on board Formosat-8B (FS-8B), a satellite made by the Taiwan Space Agency (TASA) and scheduled to launch in 2026. The goal of GTM is to detect and localize Gamma-Ray Bursts (GRBs). GTM consists of two identical modules located on opposite sides of FS-8B. Each module utilizes 2 CITIROC chips to manipulate 4 detectors, which are composed of GAGG(Ce) scintillators coupled with Silicon Photo-Multipliers (SiPMs) and oriented in various directions to achieve all-sky coverage.

The content of this thesis can be split into two parts. In the first part, based on simulations, the detection efficiency is larger than 50 % when the GRB fluences (in the energy range from 10 keV to 1 MeV) are larger than 6e-7 and 2e-6 erg/cm^2 for Short GRBs (SGRBs) and Long GRBs (LGRBs), respectively. Therefore, GTM is expected to detect about 50 GRBs per year, according to the Fermi/GBM 10-year observation of the GRB-fluence distribution and GTM's 36 % duty cycle. For localization capability, the localization uncertainty at a 3-sigma confidence level for LGRBs with fluences of 4e-6 and 4e-5 erg/cm^2 is about 30 and 3 degrees, respectively.

In the second part, considering to the dead time of a CITIROC chip, the GRB saturation fluences for SGRBs and LGRBs were estimated to be about 3.1e-4 and 5.0e-3 erg/cm^2, respectively. Moreover, to interpret the GTM readout signal in terms of energy, several calibration measurements were conducted. Despite encountering issues with light-sharing and the SiPM saturation effect in the data, the energy spectrum can still be recovered. At 662 keV, the energy resolution of the GTM is about 15 %. The linear variations in the relationship between photon energy and readout signal demonstrate that greater gain is achieved by increasing voltage or decreasing temperature.

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