康卜吞成像光譜儀(COSI)是一個以高空氣球載運的伽瑪射線望遠鏡，過去被簡稱為NCT，搭載十二個具三維空間敏感度的鍺偵測器。2009年在新墨西哥州有一次成功的氣球飛行，並成功觀測到蟹狀星雲影像。而後我們對儀器進行升級，主要改變是鍺偵測器的配置從2x2x3改成2x6，升級後的儀器將會在2014年十二月在南極洲進行約60至100天的長時間高空氣球飛行。
在2014年的飛行之中，我們主要的觀測目標為伽瑪射線爆。根據伽瑪射線爆的強度與飛行時間，我們預估至少可觀測到一次事件。作為一個康卜吞望遠鏡，康卜吞成像光譜儀可靈敏的測量光源的偏極化。
本篇論文主要探討的為此康卜吞成像光譜儀的偏極化性能，在考慮整個儀器的模型與背景輻射模型後，我用蒙地卡羅模擬出康卜吞成像光譜儀最小可測量的伽瑪射線爆偏振。

The COmpton Spectrometer and Imager (COSI), known as the NuclearCompton Telescope (NCT) before, is a balloon-borne soft gamma-ray (0.2-5MeV) telescope. COSI consists of twelve germanium strip detectors that are 3D position-sensitive. NCT had a successful balloon flight in 2009, and the upgraded instrument as COSI will be launched for an ultra-long duration balloon (ULDB)flight (60-100 days) in Antarctica in December, 2014. The most important change is the conguration of germanium detector array, which becomes 2x2x3 instead of 2x6 in NCT.
In the 2014 ULDB ight, our main targets are Gamma-ray bursts (GRB), which are expected to be observed more than once in our observation depending on its fluence and the flight duration. As a Compton telescope, COSI is intrinsically sensitive to polarization. To assess COSI's polarization performance, I estimated the minimum detectable polarization (MDP) of these GRBs with Monte-Carlo simulations, considering a revised mass model as well as the contribution of background.

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