BESⅢ桶部电磁量能器优化设计的Monte Carlo模拟

Monte Carlo Simulation of Barrel Shower Counter of BESⅢ for Better Design

运用模拟软件GEANT3对铅加闪烁光纤类型的BESⅢ桶部电磁量能器(BSC)进行了模拟 .研究表明 ,BSC中簇射的时间信息的读出有助于改善z向分辨、π0 的质量分辨和排除假光子 .模拟计算还给出了BSC能量分辨率( 6% /E) ,方向角分辨与读出粒度的关系 ,π0 质量分辨率σm/m与光输出、光纤衰减长度及读出粒度的关系 ,其中m为两个光子重建为π0

With GEANT3 frame, we simulate the lead-scintillating fiber type barrel shower counter (BSC) of BESⅢ. The structure of BSC in the simulation is analogous to Φ Factory's, and it's thinkness is 14.4X 0. The simulations show that the shower time information read-out is necessary for improving the Z spatial resolution, the π 0 invariant mass resolution and for rejecting fake photons. Also, the energy resolution σ E/E(6%/E), the relation of  angle resolution σ  with readout granularity and the relations of mass resolution of π 0 σ m/m with light yield, attenuation length, readout granularity are given, where m is the invariant mass of π 0 reconstructed by two photons.