Development of a particle detector in the microbeam cell irradiation equipment SPICE

Single Particle Irradiation System to Cells (SPICE) is set up in the Electrostatic Accelerator Facilities to irradiate the known amount of accelerated particles to the target cell. This report describes the property of the particle detector in SPICE at its development where the number of proton particle and the stage drive were to be regulated by the detector consisting from the scintillator (NE102AeQ, Oyo Koken Kogyo Co., Ltd.) + photomultiplier tube (R7400U-03, Hamamatsu Photonics K.K.) (PMT). The precision of the present post cell detector to control the particle number was evaluated using the plastic plate for solid-state track detection CR-39 (100 mc-m thick, Fukuvi Chem. Ind.), 20 x 10 mm, to which 1,500 protons were shot so as to form a lattice pattern with every 20 mc-m space: id est (i.e.), 1 proton/lattice was preset as an input value and the resultant etched pit number on the image (1024 x 1024 pixel (0.305 mc-m/pixel) was observed by microscopy together with PMT counts. It was revealed that the rate of successful 1 etch pit vs preset value 1 was 98% and 1 PMT proton count vs preset value 1, 95%, indicating the satisfactory control of particle number was attained. Now SPICE can irradiate 400-500 protons/min of 3.4 MeV to a target cell nucleus as their focused microbeam of diameter 2 mc-m. (T.T.)