空间大动态范围三维成像量能器研究

A 3D-imaging calorimeter is proposed for the search of dark matter and direct observation of cosmic rays. The calorimeter, which is five-sides sensitive, is one order of magnitude higher in geometric factor than traditional calorimeters composed of orthogonal scintillator strips. It maintains measuring accuracy of particle energy by giving enough longitudinal interaction length at all possible directions. Therefore, observation of particles with energy up to PeV can be achieved. The calorimeter is composed of nearly 10 k pieces of LYSO crystals, whose light signals are readout by wavelength-shifting fiber + ICCD system. By studying the linear response to multiple injected particles and by developing a 1×3 fiber splitter which has 3 outputs in different scales, we aim to fulfill 1e6 dynamic range for the whole calorimeter system. The design concept of 3-dimensional imaing and five-sides sensitivity will be verified. We will study different encapsulation method for the crystals and different coupling of the fibers. We will develop a small scale prototype for the 3d calorimeter and perform high energy beam test using this prototype. The energy resolution and e/p discrimination capability will then be verified.

我们提出一种用于在轨进行暗物质观测和宇宙射线测量的新型三维成像量能器。三维成像量能器五面灵敏，几何因子比传统的条形正交构型量能器大一个量级以上；有足够的纵向相互作用长度保证良好的能量探测能力,可有效扩展探测能区至PeV以上。 三维成像量能器由近万块LYSO晶体组成，晶体信号通过波长转移光纤+ICCD系统读出，本项目以满足全系统6个量级的动态范围需求为着眼点，研究LYSO晶体的粒子入射线性响应特性，研制1分多光纤分路器以提供多量程输出。以三维成像五面灵敏的设计概念的可行性为目标，研究不同晶体封装和不同光纤耦合方式的优劣，研制一套小规模三维成像量能器原理样机，进行SPS高能粒子束流实验以完成能量分辨等指标的验证。

本项目围绕创新的三维成像量能器开展性能研究。研制了三套量能器原理样机并参加欧洲核子中心的高能粒子束流验证实验。实测结果显示，量能器原理样机实测能量分辨率分别好于1.3%@200 GeV（电子）和21.0%@400 GeV（质子）。利用1/15规模量能器原理样机，得到e/p粒子鉴别能力好于10-4，达到了预期目标。.实验表明，三维量能器方案和光纤+增强型相机信号读出方案进行高能量分辨和大动态范围观测是完全可行的。HERD项目的粒子能量分辨率、粒子鉴别能力等核心技术指标都得到完美验证，极大推动了HERD工程立项工作。