离线自刻度技术在高海拔宇宙线实验中的应用与研究

时间刻度是保障宇宙射线观测装置的指向精度和角分辨等核心性能的关键环节，直接关系到能否在准确的方向上发现宇宙线加速源。高海拔宇宙线观测站(LHAASO)是目前世界上规模最大、探测能区最高的新一代实验装置，将对100TeV以上能区的伽马射线进行巡天观测，从而认证宇宙线加速起源。其占地一平方公里的阵列内包含5242台电磁粒子探测器，刻度如此规模的探测器在此领域尚无先例可循，依靠传统的硬件刻度技术已不可行。前期研究表明，离线刻度技术具有很高的效率和亚纳秒量级的时间刻度精度，本项目首次将该技术应用于LHAASO一平方公里阵列，利用实验数据中的大气簇射事例精确刻度探测器的时间信息，从而解决大规模探测器刻度面临的困难，保障装置的角分辨在10年运行期间内的稳定性。本项目也为下一代更大规模的宇宙线实验提供一种理想的刻度方式，有助于推动超高能伽马天文领域迈向更精细的观测研究阶段。

Time calibration is critical to guarantee the angular resolution and pointing accuracy of cosmic ray observation, which is directly related to the ability to find the origin of the cosmic ray. Large High Altitude Air Shower Observatory (LHAASO) is a new generation experiment in China, which will become the world’s largest, highest energy gamma ray observatory. With the aim of discovering origin of cosmic ray, it will survey the northern hemisphere sky for gamma ray sources above 100TeV. However, hardware time calibration becomes infeasible as the number of detector in the LHAASO one square kilometer array reach 5242. Previous study found offline calibration can be used to determine the detector time offset constants at the sub-nanosecond level with high efficiency. In this project, an offline self-calibration method which relies on the measurement of charged particles within the extensive air showers will be studied, to ensure the stability of the angular resolution of LHAASO. This study also offers an ideal method to real time calibrate the detector performances for next generation cosmic ray experiments covering an area above square kilometers scale, enabling the observatory to provide more precise data.