The Research For The Simulation And Measurement Of The Mixed Radiation Field On E2 Line Of BEPCⅡ Test Beam Facility

BEPCⅡLINAC-Test Beam (Beijing) consisting of three lines:E1, E2 and E3, with the respective function, is the only test beam for the high-energy physics experiment in China. The movable targets are set up afterward the electron beam inject jet to get different kinds of single mono-energetic particle beam for the high energetic detector calibration in the second target chamber on E2 line. The mixed radiation field consists of different secondary particles including e±,π±, n, p,γandμ±(fromπ±decay) is formed on E2 line after the interaction between electron beam and the object target such as beryllium carbon, aluminum, copper, tungsten. The radiation field, in addition to provide the E3 line variable momentum single charged particle beam, is still used for various irradiation experiment, such as material irradiation, crop breeding induced mutations, optical fiber links irradiation injury, etc. These experiments all need to know the sample absorbed doses, particularly absorbed dose and fluence of different variable energetic particles. Therefore, the research for mixed radiation field simulation and the development of a mixed radiation detector suitable for high-energy particle mixed field measurement are urgent tasks for Test Beam upgrade.This paper will introduce the mixed radiation field simulation by using FLUKA simulation software and the development of mixed radiation detector, named Phoswich Scintillation Detector (PSC). First of all, the spectrum of different kind secondary particles over total solid angle, the angular distribution of various secondary particle over the total energy and the double differential flounce versus particle energy and polar angle refer to beam inject direction are acquired by the FLUKA simulation. Then, the mixed radiation detector (PSC) was successfully designed and developed in reference to the radiation field simulation result. The performances of the detector, including counter plateaus, GEANT4 simulation of detection efficiency for different kind secondary particles and particle discrimination especially n—γdiscrimination were completely studied and tested. The signal from the PMT of the Phoswich Scintillation detectors can be measured and discriminated without amplification, with the signal amplitude higher than 500 mV. The counter plateau voltage ranges broad from 1800V-2500V.The detection efficiencies of charged particles (e±,π±,μ±,p) and neutral particles(n,γ) all reach the design index, the former is higher than 97% and the latter ranges from 10% to 40%.The performance of particles discrimination, especially n—γdiscrimination is favorable in extensive energy ranges, attains to the expectant design request. At present, the detector is assigned in the second target room of Beijing Test Beam Facility, in order to study its discrimination performance of more than two kinds of mixed particles.This paper covers the following aspects:brief introduction to Beijing Electron-Positron Collider (BEPCⅡ) and Test Beam Facility (TBF), Monte Carlo method and FLUKA and GEANT4 simulation program introduction, The Monte Carlo simulation of mixed radiation field in target chamberⅡin TBF, the design and development of mixed radiation detector, the research to the performance of the mixed radiation detector (PSD) and the summary and expectation.