基于延迟线读出RPC的宇宙线成像系统研究

Based on the cosmic ray muon scattering angle distribution for different substances, a cosmic muon imaging system can be built for the detection of high Z material. In order to build this imaging systems, large-area detectors with high efficiency, high position resolution and cost-effective should be implemented, together with related simulation and analysis programs. ..In our previous work, new kind of glass Resistive Plate Chambers (RPCs) were built and applied to measure the spatial resolution of the detector. The effective area of the RPC is 200×200mm2. Readout strips are collected to a LC delay-line and time difference is used to determine the position. In average a spatial resolution of 0.90 mm (FWHM) is obtained for a single RPC, with a good uniformity across the detection area. These RPCs are also very promising detectors for Muon Tomography(MT). Preliminary imaging results of a Muon Tomography Station prototype based on these RPCs show that Fe and Pb bricks of 3cm thickness can be discriminated...At the next stage, we plan to construct larger delay-line readout RPCs with effective area of 1m2. A practicable Muon Tomography station would be build and related reconstruction algorithm would be studied.

近年来，对宇宙射线成像系统的研究成为粒子物理与核物理科技应用领域的一个热点。搭建宇宙成像系统的关键技术与难点在于研发大面积、高位置分辨率、高性价比的宇宙射线探测器。阻性板气体室（Resistive Plate Chamber，简称 RPC）被认为有着面积、高性价比和易维护的特性。我们的前期工作已经成功地研发了基于延迟线读出的灵敏面积为20cm×20cm的RPC探测器，经测试它对宇宙线μ子的分辨率达到亚毫米，同时可大幅降低电子学路数的需求，是一种理想的宇宙线μ子成像探测器。我们使用它搭建了一个小型的宇宙线成像系统原型机，成像初步结果表明这种该原型机可区别厘米尺度的铁和铅块。.　　希望本项目得到后续经费支持，我们将会研究延迟线读出的RPC技术应用在更大面积（1m×1m)的RPC上的情况，并且搭建一个中等大小的宇宙线成像系统。

宇宙射线成像系统的研究成为粒子物理与核物理科技应用领域的一个热点 。阻性板气体室（Resistive Plate Chamber，简称RPC）被认为有着面积、 高性价比和易维护的特性，非常适合于宇宙射线成像系统。本项目掌握了50cm*50cm基于延迟线读出的高精度大面积玻璃RPC的制作技术，单层RPCμ子探测效率90%，位置分辨率大约在1mm。实验了纯R134A气体的RPC探测器的性能。我们成功用这种RPC搭建了宇宙射线成像系统，并且获得了不错的成像结果，可以分辨出铅块和铁块的散射角不同以及看到清晰的物体轮廓。开发了GEANT4对宇宙射线成像系统模拟程序模拟程序并且和实验比较吻合，下一步可以基于模拟开发新的成像算法。