Influence of Particle Incidence Angle on the Detection Efficiency of Plastic Scintillator Detector

When the scintillation detector is used to identify particles and position the location of radioactive source or other particle emitters, the detection efficiency has an important influence on the experimental results, and the incident angle of the particle entering the scintillation detector will affect the detection efficiency of the detector, furthermore affect the precision of positioning. In order to analysis the effect of detection efficiency due to the difference of incidence angles, this paper analysis the influence of the incidence angle for EJ299-33A plastic scintillator with size 6 (mm) ×6 (mm) ×130 (mm), under the simulation, 2 MeV source radioactive particles entering the detector at different incident angles. By the simulation, it is finding that when the incident angle of particles increases gradually from 0°to 90°in the same plane, the detection efficiency increases rapidly at 0°~30°and decreases gradually at 30°~90°. Furthermore, through the analysis of different detection efficiency in different planes, it is founded that the maximum detection efficiency lies on the plane where the azimuth angle is 0°or 90°. And through the experiment test, the detection efficiency obtained from simulation is agreed to the experimental test in the X-Z plane. Finally, we can conclude that when the incidence angle of the particle between 20°~30°and the azimuth angle is 0°or 90°, the detection efficiency reaches the highest. This conclusion can be applied to experiments such as particle identification and positioning of undiscovered radioactive source.