Performance Investigation On The Time Of Flight Detector In RIBLL

Time of flight detector plays an essential role for the identification and isolation of radioactive ion beam in all the particle identification detectors in RIBLL. Hence, it is necessary to study the TOF detector performance so as to find a reasonable solution to improve it. In this paper, the performance of TOF in RIBLL was simulated and then studied.Firstly, we constructed TOF detector consistently with experimental set up using Monte Carlo Kit GEANT4, defined the ion source and all the corresponding physical process. Of all the physical process, low energy electromagnetic processes is the main interaction between incident particle and scintillator, while photon absorption process,boundary process and photon transmission are also involved.Secondly, the detector performance is studied intensively. The results show that total photon collection efficiency is associated with the particle incident location on scintillator, time resolution is related to the kinds of incident particle, incident position, energy and reflectivity of Aluminum reflector. Different heavy ions were selected with same size of beam spots, and simulated, then time resolutions was achieved respectively. The total photon collection efficiency is best when incident particle location is of the center of scintillator. When the incident point is a litter lower to the center, the time resolution is best. If Aluminum reflectance is smaller, the number of photons with only one reflection arriving at the photocathode will be larger, the number of photons with 2 reflections will be smaller, which causes a better time resolution. The energy of the incident particle influence the time resolution greatly. The time resolution became worse following the increase of incident energy.Finally, combining the results of the simulation and further analysis, discussion, we put forward some suggestions and improvements to the TOF detector.