The Large Size Telescope (LST) is the largest telescope of the Cherenkov Telescope Array project, with a diameter of 23 m and a focal plane instrumentation of 4 square meters. In the current design, it comprises cameras equipped with arrays of 1855 photomultiplier tubes (PMTs). Each PMT has a light concentrator in front to reduce the stray light as well as reduce the dead space between PMTs. These cameras are built to detect the nanoseconds flash of Cherenkov light emitted from atmospheric air-showers generated by a cosmic gamma ray entering the atmosphere. Thanks to a rapid development, silicon photomultipliers (SiPMs) are becoming valid alternatives for PMTs in several fields, due to their lower operating voltage, larger photon efficiency, reduced ageing, insensitivity to magnetic fields, and possibly lower costs. These properties make SiPMs suitable for gamma-ray astronomy and future development for imaging atmospheric Cherenkov telescopes. Here we discuss a minimal-effort scenario for an upgrade of an LST PMT-based camera to a SiPM-based camera, in which most of the hardware is maintained. Thanks to a ray-tracing software, we show that the minimal valid solution consists only in replacing each PMT by several SiPMs. In particular, the current PMT-tailored lightguides in front of each pixel do not have to be exchanged considering the angular distribution of light at the SiPM surface and its angular response. We briefly discuss the effect on the sensitivity of the instrument equipped with SiPM.

大型望远镜（LST）是切伦科夫望远镜阵列项目的最大望远镜，直径为23 m，焦平面仪器为4平方米。在当前设计中，它包括配备有1855个光电倍增管（PMT）阵列的相机。每个PMT前面都有一个聚光器，以减少杂散光并减少PMT之间的死区。这些摄像机的构建是为了检测由宇宙伽马射线进入大气层而产生的大气喷头发出的切伦科夫光的纳秒级闪光。由于飞速发展，硅光电倍增器（SiPM）由于其较低的工作电压，较大的光子效率，减少的老化，对磁场不敏感以及可能更低的成本，已成为多个领域中PMT的有效替代品。这些特性使SiPM适合于伽马射线天文学以及对大气Cherenkov望远镜成像的未来发展。在这里，我们讨论了将基于LST PMT的摄像机升级为基于SiPM的摄像机的最省力的方案，其中大部分硬件都得到了维护。借助光线跟踪软件，我们证明了最小的有效解决方案仅在于用多个SiPM替换每个PMT。特别地，考虑到SiPM表面处的光的角度分布及其角度响应，不必更换每个像素前面的当前PMT量身定制的光导。我们简要讨论了对配备SiPM的仪器灵敏度的影响。在这里，我们讨论了将基于LST PMT的摄像机升级为基于SiPM的摄像机的最省力的方案，其中大部分硬件都得到了维护。借助光线跟踪软件，我们证明了最小的有效解决方案仅在于用多个SiPM替换每个PMT。特别地，考虑到SiPM表面处的光的角度分布及其角度响应，不必更换每个像素前面的当前PMT量身定制的光导。我们简要讨论了对配备SiPM的仪器灵敏度的影响。在这里，我们讨论了将基于LST PMT的摄像机升级为基于SiPM的摄像机的最省力的方案，其中大部分硬件都得到了维护。借助光线跟踪软件，我们证明了最小的有效解决方案仅在于用多个SiPM替换每个PMT。特别地，考虑到SiPM表面处的光的角度分布及其角度响应，不必更换每个像素前面的当前PMT量身定制的光导。我们简要讨论了对配备SiPM的仪器灵敏度的影响。考虑到SiPM表面光的角度分布及其角度响应，不必更换每个像素前面的当前PMT量身定制的光导。我们简要讨论了对配备SiPM的仪器灵敏度的影响。考虑到SiPM表面光的角度分布及其角度响应，不必在每个像素前面调整当前的PMT尺寸的光导。我们简要讨论了对配备SiPM的仪器灵敏度的影响。