A method to localize gamma-ray bursts using POLAR
A method to localize gamma-ray bursts using POLAR
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DOI：
10.1016/j.nima.2010.10.006
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发表时间：
2010-11
影响因子：
1.4
通讯作者：
E. Suarez-Garcia;D. Haas;W. Hajdas;G. Lamanna;C. Lechanoine-Leluc;R. Marcinkowski;A. Mtchedlishvili-A.-Mtchedlishvi
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文献类型：
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作者：
E. Suarez-Garcia;D. Haas;W. Hajdas;G. Lamanna;C. Lechanoine-Leluc;R. Marcinkowski;A. Mtchedlishvili-A.-Mtchedlishvi
硬X射线偏振计POLAR的目标是测量γ射线暴（GRB）瞬发发射的50- 500 keV光子的线偏振。需要探测到的伽玛暴在天空中的位置来确定它们的偏振水平。我们在这里提出了一种方法，通过该方法，尽管偏振仪无法拍摄图像，伽玛暴可以粗略地单独使用极定位。为此，定标器连接到25个多阳极光电倍增管（MAPM）的输出端，MAPM收集来自POLAR闪烁体靶的光。每个定标器测量有多少GRB光子在相应的MAPM中产生至少一个高于50 keV的能量沉积。模拟结果表明，25个定标器的相对输出依赖于伽玛暴的位置。在10201个位置模拟的非常强的伽玛暴的数据库已经产生。当探测到伽玛暴时，通过比较测量的定标器模式和数据库中的χ 2的最小值来计算伽玛暴的位置。这种伽玛暴定位技术带来了足够的精度，使得对于注量Ftot≥10−5ergcm−2的伽玛暴，传递到100%调制因子的误差保持在10%以下。在没有其他仪器同时观测同一视场的情况下，POLAR定位能力将是有用的。
The hard X-ray polarimeter POLAR aims to measure the linear polarization of the 50–500keV 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 50keV 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 10201 positions has been produced. When a GRB is detected, its location is calculated searching the minimum of the χ2obtained 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.