高计数率MRPC工作稳定性研究

Multi-gap Resistive Plate Chamber (MRPC) developed with low resistive glass has good time resolution (<100ps) and high efficiency (>95%). It can work at very high flux rate(>25kHz/cm^2) and it will be used in many large-scale high energy experiments. Our low resitive glass and high rate MRPC will be adopted by FAIR-CBM to construct time of flight system. Compared with common glass MRPC, the low resistive glass MRPC has big difference in material performance, noise, aging performance and transit response. This project is closely related with the requirement of world big scientific experiment and it is aimed to do research on the stability of high rate MRPC, aging performance and stability working point changing with radiation dosage. We will aslo study on signal transmission and crosstalk and do optilmal design of MRPC. All of these research have very important scienticif and realistic meaning for expanding MRPC usage area and assuring its excellent performanc and long time stability.

采用低电阻玻璃制成的多气隙电阻板室（MRPC-Multigap Resistive Plate Chamber）具有时间分辨好(<100ps)，效率高（>95%），能承受的粒子计数率高(>25kHz/cm^2)等特点，在许多大型高能物理实验中有广泛应用，德国的FAIR－CBM实验决定采用我们研制的高计数率MRPC建造飞行时间探测器。低电阻玻璃MRPC与普通玻璃MRPC在材料性能，噪声性能,抗辐照性能和瞬态工作性能等方面存在很大差异。本课题紧密结合国内外大科学工程的需求，研究高计数率MRPC的高压稳定性，抗辐照性能和稳态工作点随辐照剂量变化性能，研究MRPC信号传输及串扰性能，对MRPC进行优化设计。这些研究对扩大MRPC技术的应用领域，保证MRPC的优良性能和长期稳定可靠运行，具有重要的科学意义及现实意义。

项目紧密围绕高计数率MRPC工作稳定性进行研究。研制出了CBM－TOF中心区域2cm×2cm pad读出的高计数率MRPC原型探测器。其时间分辨达40ps，探测效率高达98%，计数率能力达70kHz/cm^2。达到国际领先水平。研制出适合于CBM-TOF的条形读出高计数率MRPC，时间分辨达50ps，探测效率高达98%，各项性能均满足CBM-TOF要求，已被CBM采用。针对高亮度物理实验中存在的气体探测器的气体污染问题，创新性地研制出自密封的高计数率MRPC探测器，大大加快了气体交换速度，时间分辨达60ps，探测效率达98%，表现稳定，为解决气体污染问题提供了一种全新的解决方案。为了研究得到高计数率MRPC探测器的长期工作稳定性，建立了MRPC辐照实验装置和MRPC性能计算机自动实时记录系统。经过长达36天的高剂量X射线辐照，MRPC中累积电荷达0.1C/cm^2，相当于CBM实验TOF中半年的累积电荷。MRPC的各项性能如探测效率，时间分辨，Cluster size等均无明显变坏，表明高计数率MRPC具有很好的长期工作稳定性。采用高能中子束流测试了低电阻玻璃的抗辐照性能，当中子照射量达10^14中子/cm^2时，玻璃体电阻无明显变化，证明了低电阻玻璃的良好抗中子辐照性能。