应用于NICA-MPD的Shashlik取样型电磁量能器性能模拟  

Performance simulation of a Shashlik sampling electromagnetic calorimeter for NICA-MPD

作　　者：曾德凯 彭肖宇 魏鑫 程凯 季选韬 朱坤 屈国普[1] 胡创业[1] 王晓冬[1] ZENG Dekai;PENG Xiaoyu;WEI Xin;CHENG Kai;JI Xuantao;ZHU Kun;QU Guopu;HU Chuangye;WANG Xiaodong(School of Nuclear Science and Technology,University of South China,Hengyang 421001,China)

机构地区：[1]南华大学核科学技术学院,衡阳421001

出　　处：《核技术》2021年第8期16-26,共11页Nuclear Techniques

基　　金：中国科学技术部基金(No.2020YFE0202001);国家自然科学基金(No.11875163、No.11605086);湖南省自然科学基金项目(No.2018JJ3422);湖南省教育厅基金项目(No.18C0461、No.19B487、No.19C1596、No.19B488)资助。

摘　　要：俄罗斯重离子超导同步加速器的多功能探测器(Nuclotron-based IonColliderFacility'sMultiPurpose Detector,NICA-MPD)采用Shashlik取样型电磁量能器(ElectromagneticCalorimeter,ECAL),设计为由32个扇区组成的圆柱形桶共包含有43008个构层(tower),每个tower由220层吸收体铅片与塑料闪烁体片交替组成。本文对影响其性能的多个参数进行了模拟研究,利用GEANT4软件模拟了影响电磁量能器的能量沉积、能量泄漏、能量分辨率等多种参数。模拟结果表明:不同物质作为吸收体时,高原子序数(Z)物质有利于能量沉积,并且能量主要沉积在吸收体中,占比为65%左右;在兼顾能量分辨率与位置分辨率需求后,电磁量能器的每个tower横截面边长设置为4 cm为最优;由于单个tower中横向泄漏大于30%,是能量泄漏的主要原因,因此在实验中可考虑在侧面加涂具有反射作用的涂料层;对于3×3 tower多个组合情况,当吸收体与闪烁体总厚度为1.8 mm时,且吸收体铅为0.3mm时,能量分辨率能达到满足实验需求的5%@3 GeV;在不同入射能量下,量能器的能量沉积具有良好的线性关系,多个tower组合能提高能量分辨率与能量沉积,且能量越高时,能量分辨率越好。另外通过模拟计算表明,当辐射长度达到13X_(0)时,能量沉积达到最大值,同时得到最佳的能量分辨率,因此NICA-MPD的电磁量能器设计长度约为415 mm,等效于电子经过约12.8个辐射长度。Tower侧面增加反射层能够使移波光纤中的光子数提高10%~19%,光纤端面增加反射层能使到达探测器的光子数提高约50%,验证了增加反射层的重要性和必要性。[Background]The Shashlik electromagnetic calorimeter(ECAL)is used in the Nuclotron-based Ion Collider Facility's MultiPurpose detector(NICA-MPD)of the Russian heavy ion superconducting synchrotron.It is designed as a cylindrical barrel divided into 32 sectors with a total of 43008 towers.Each tower is composed of 220 layers of lead and 221 layers of scintillator alternately.[Purpose]This study aims to simulate multiple parameters of Shashlik ECAL for NICA-MPD that affect the performance of ECAL.[Methods]First of all,the module of ECAL tower was built based on the principle of Shashlik ECAL.Then,the GEENT4 software was employed to simulate the performance of every single tower of ECAL according to its structure composition.Considering the influence of the design parameters of the scintillator and absorber on energy deposition,energy resolution,and energy leakage after electrons were incident on the tower and the subsequent scintillator luminescence process,the influence of the reflective layer on the number of photons was in the wavelength shifted fiber and detector.Finally,factors that affected energy deposition,energy leakage,energy resolution,and photon number in the wavelength shift(WLS)and sensor,and the influence of the thickness,number of layers,and size of the scintillator and absorber in the module on energy deposition,energy leakage,and energy resolution were simulated and analyzed.[Results]The simulation results show that the best side length of cross-section of each tower is 4 cm.When the total thickness of absorber and scintillator is 1.8 mm and the thickness of lead absorber is 0.3 mm,the energy resolution meets the experimental requirements of 5%@3 GeV.When the radiation length reaches 13X0,maximum energy deposition and obtains better energy resolution can be achieved.Adding a reflective layer to the tower side can increase the number of photons in the fiber by 10%~19%whereas adding a reflective coating to the fiber end can effectively increase the number of photons reaching the detector by 50%.[Con

关 键 词：电磁量能器 GEAN4模拟 能量沉积 能量分辨率 能量泄漏 

分 类 号：TL99[核科学技术—核技术及应用]