高精度气体径迹探测器及激光校正的研究

In recent years, in order to measure the elementary particles (such as Higgs) precisely, the performance requirement of the tracking detector reaches a high level that well beyond what was achieved before, and the development and the calibration of the tracking system becomes one of the key issues that have to be solved in the coming experiment. The gaseous detector sub-group of Tsinghua University and Institute of High Energy Physics tracked and involved a lot in the field. A TPC prototype using GEM as readout with an active area of 100mm^2 has been developed in Tsinghua University, and a two-dimensional X-ray imaging detector using GEM with the active area of 200mm^2 has been investigated in Institute of High Energy Physics. All of the detectors achieved a position resolution better than 150µm. To meet the requirements of the Higgs physics for high-precision detection and the other related experiments with the higher spatial accuracy, a high precision tracking detector prototype will be developed, with a drift length of 500mm, ~1000 electronics channels, and using GEM foils as the readout with 200mm×200mm effective detection area. The position resolution of about 100µm is expected under 1.0 Tesla magnetic field. A laser calibration system is essential to measure and calibrate its performance. In the study, the calibration method and algorithm based on laser will be explored. The methods of 2D and 3D laser calibration will be test and the reconstruction algorithm should be given. The technical experience accumulated would provide a strong scientific basis for the tracking detectors in the coming application.

近年来，为了实现对Higgs等基本粒子的精确测量，大型对撞实验中对径迹探测器的性能要求超过了以往任何实验，如何研制和标定如此高精度的径迹探测器已成为下一代此类对撞机实验谱仪系统必须突破的难点。清华大学和高能物理研究所在此领域一直有跟踪和研究投入，分别自主开展了有效读出面积100mm^2的TPC探测器原型机和200mm^2GEM二维X射线成像探测器研究，成功实现了优于150µm的位置分辨。本项目在双方的研究基础之上，针对高精度径迹探测和相关高位置精度实验需求，研制有效面积200mm×200mm 的GEM读出、漂移长度500mm和约1000路小单元读出的高精度径迹探测器，实现1T磁场下100µm的位置分辨结果。为此需要建立激光刻度系统，研究基于激光系统的标定和刻度算法，建立2D和3D的激光标定方法，给出激光标定修正算法。以期解决研制和标定中的关键技术问题，为今后大型谱仪系统的研发打下基础。

近年来，为了实现对Higgs等基本粒子的精确测量，大型对撞实验中对径迹探测器的性能要求超过了以往任何实验，如何研制和标定如此高精度的径迹探测器已成为下一代此类对撞机实验中谱仪系统必须突破的难点。清华大学和中科院高能物理研究所在此领域一直有着持续的跟踪和研究投入。本项目在双方已有的研究基础上，针对高精度径迹探测和相关高位置精度实验需求, 研制出了漂移长度达500mm的时间投影室（Time Projection Chamber，TPC），采用有效面积200mm×200mm 的GEM探测器读出、配合1280路基于自研ASIC 前放的读出电路，以期在1T磁场下实现100μm的位置分辨结果。同时设计、建立了激光刻度系统，研究了激光的电离能力，建立了2D和3D的激光标定方法，给出激光标定修正算法。课题利用激光光束的高电离能力，在无磁场的情况下实现了优于100 um的位置分辨能力，以及好于5%的dE/dx分辨力。系统研究了影响TPC电子漂移速度长期稳定性的因素，实现了温度造成的漂移速度变化的标定。该课题的顺利完成，为实现100μm高位置分辨的时间投影室激光标定研究提供了理论和实验研究基础，特别是对国内提出的大型环形对撞机CEPC和国际上大型直线对撞机ILC实验预研。另外，系统研制的前端电子学和后续的DAQ系统，性能先进，具有可扩展性，可以推广到其他微结构气体探测器的读出，以推动国内相关研究的发展。