arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新，休息一下吧，周末愉快~~
arXiv 1107.3079astro-ph.IMphysics.ins-det
收藏

负离子TPC X射线偏振计的气体增益测量

Gas Gain Measurements from a Negative Ion TPC X-ray Polarimeter

Z. Prieskorn, J. E. Hill, P. E. Kaaret, J. K. Black, K. Jahoda

备注：
6 pages, 6 figures, accepted for publication in IEEE Trans Nucl Sci
发表信息：
IEEE T NUCL SCI. 2011;58 (4):2055-2059
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

基于气体的时间投影室（TPC）已被证明是具有优异量子效率同时实现大调制因子的高灵敏度X射线偏振计。为了观测伽马射线暴（GRB）的瞬发X射线辐射的偏振，需要一个大面积探测器。当漂移距离大时，标准TPC中的电子云的扩散可能阻碍测量良好的调制。因此，我们建议使用负离子TPC（NITPC）与硝基甲烷（CH3NO2）作为电子捕获剂。由于负离子与周围气体的热耦合，负离子的扩散比电子的扩散减少。这允许更大面积的检测器，因为漂移距离可以增加而不会使偏振计调制降级。负离子的速度也比电子慢约200倍，这使得读出电子设备的操作速度更慢，从而降低了仪器的功率。为了优化NITPC的设计，我们测量了气体增益与SciEnergy气体电子倍增器（GEM）在单和双GEM配置。每种设置都用不同的气体组合、浓度和压力进行测试：P10 700 Torr，在不同CO2浓度下的Ne+CO2 700 Torr和Ne+CO2+CH3NO2 700 Torr。我们报告增益作为总电压的函数，从GEM堆栈的顶部到底部测量，并作为上面列出的气体浓度的漂移场强度的函数。在5.9千电子伏的光电子轨道的例子也被提出。

英文摘要：

Gas-based time projection chambers (TPCs) have been shown to be highly sensitive X-ray polarimeters having excellent quantum efficiency while at the same time achieving large modulation factors. To observe polarization of the prompt X-ray emission of a Gamma-ray burst (GRB), a large area detector is needed. Diffusion of the electron cloud in a standard TPC could be prohibitive to measuring good modulation when the drift distance is large. Therefore, we propose using a negative ion TPC (NITPC) with Nitromethane (CH3NO2) as the electron capture agent. The diffusion of negative ions is reduced over that of electrons due to the thermal coupling of the negative ions to the surrounding gas. This allows for larger area detectors as the drift distance can be increased without degrading polarimeter modulation. Negative ions also travel ~200 times slower than electrons, allowing the readout electronics to operate slower, resulting in a reduction of instrument power. To optimize the NITPC design, we have measured gas gain with SciEnergy gas electron multipliers (GEMs) in single and double GEM configurations. Each setup was tested with different gas combinations, concentrations and pressures: P10 700 Torr, Ne+CO2 700 Torr at varying concentrations of CO2 and Ne+CO2+CH3NO2 700 Torr. We report gain as a function of total voltage, measured from top to bottom of the GEM stack, and as a function of drift field strength for the gas concentrations listed above. Examples of photoelectron tracks at 5.9 keV are also presented.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑