高海拔宇宙线观测实验中scaler模式的模拟研究  

Simulation study of scaler mode at large high altitude air shower observatory

作　　者：黄志成 周勋秀[1] 黄代绘[1] 贾焕玉[1] 陈松战[3] 马欣华[3] 刘栋[4] 阿西克古 赵兵 陈林 王培汉 Huang Zhi-Cheng;Zhou Xun-Xiu;Huang Dai-Hui;Jia Huan-Yu;Chen Song-Zhan;Ma Xin-Hua;Liu Dong;AXi Ke-Gu;Zhao Bing;Chen Lin;Wang Pei-Han(School of Physical Science and Technology,Southwest Jiaotong University,Chengdu 610031,China;Key Laboratory of Cosmic Rays,Ministory of Education,Tibet University,Lhasa 850000,China;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;Institute of Frontier and Interdisciplinary Science,Shandong University,Qingdao 266237,China)

机构地区：[1]西南交通大学物理科学与技术学院,成都610031 [2]西藏大学宇宙线教育部重点实验室,拉萨850000 [3]中国科学院高能物理研究所,北京100049 [4]山东大学,前沿交叉科学青岛研究院,青岛266237

出　　处：《物理学报》2021年第19期352-359,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2018YFA0404201);国家自然科学基金(批准号:U2031101,11475141,12047576,U1931108);西藏大学宇宙线教育部重点实验室(批准号:KLCR-202101)资助的课题。

摘　　要：位于四川省稻城县海子山的高海拔宇宙线观测站(LHAASO)包含3个子阵列,即地面粒子探测器阵列(KM2A)、水切伦科夫探测器阵列(WCDA)和广角大气切伦科夫望远镜阵列(WFCTA).作为LHAASO实验的主阵列,KM2A由5195个地面电磁粒子探测器(ED)和1188个地下缪子探测器(MD)组成.对地面宇宙线观测实验来说,常有两种独立的数据采集模式,即shower模式和scaler模式.本文通过Monte Carlo方法,利用CORSIKA软件包和G4KM2A软件包,对KM2A-ED阵列中的scaler模式进行了模拟研究.当64个ED作为一个cluster、符合时间窗口为100 ns时,多重数m≥1,2,3和4的计数率分别约为88 kHz,1400 Hz,220 Hz和110 Hz.对scaler模式探测原初宇宙线的能量和有效面积也进行了模拟计算,发现KM2A-ED中多重数m≥1时探测原初质子的阈能可降低到100 GeV、有效面积高达100 m^(2).本模拟结果为LHAASO-KM2A实验中进行scaler模式的数据触发提供了具体方案,为后续的实验数据分析提供了信息.A large high altitude air shower observatory(LHAASO) located at Daocheng in Sichuan province,China,with an altitude up to 4410 m above the sea level,takes the function of hybrid technology to detect cosmic rays.It is composed of three sub-arrays:a 1.3 km2 ground-based particle detector array(KM2 A) for γ-ray astronomy and cosmic ray physics,a 78000 m2 water Cherenkov detector array(WCDA) for γ-ray astronomy,and 18 wide field-of-view air Cherenkov/fluorescence telescopes array(WFCTA) for cosmic ray physics.As the major array of LHAASO,KM2 A is composed of 5195 electromagnetic particle detectors(EDs,each with 1 m2)and 1188 muon detectors(MDs,each with 36 m2).In the ground-based experiments,there are two common independent data acquisition systems,corresponding to the shower and scaler operation modes.Up to now,the KM2 A array operates only in shower mode with the primary energy threshold of about 10 TeV.In the scaler mode,it is not necessary for too many detectors to be hit at the same time.The energy threshold of the experiment can be greatly lowered.In order to learn more about the scaler mode in LHAASO-KM2 A,we adopt the CORSIKA 7.5700 to study the cascade processes of extensive air showers in the atmosphere,and employ the G4 KM2 A(based on Geant4) to simulate the detector responses.The KM2 A-ED array is divided into dozens of clusters.For one cluster(composed of 64 EDs),the event rates of showers having a number of fired EDs ≥ 1,2,3,4(in a time coincidence of 100 ns) are recorded.The average rates of the four multiplicities are~88 kHz,~1400 Hz,~220 Hz,and ~110 Hz,respectively.The particle multiplicities m≥3 are almost completely due to cosmic ray secondary particles.The corresponding primary energies and effective areas are also given in this paper.According to our simulations,the energy threshold of the scaler mode can be lowered to 100 GeV,and the effective areas reach up to ~100 m^(2).The simulation results in this work are helpful in the online triggering with the scaler mode,and provide information f

关 键 词：宇宙线 Scaler模式 Monte Carlo模拟 

分 类 号：P172.4[天文地球—天文学]