Feasibility study of organic single crystal semiconductor detector for heavy ion beams

Organic semiconductors were thin, flexible, printable and inexpensive devices. Therefore, radiation detectors using organic semiconductors are expected to be highly suitable for carbon therapy dosimeters. From this point of view, we are developing dosimeters for carbon beam therapy focusing on tissue equivalence which is one of the useful properties of the organic semiconductors. In this year, we developed and evaluated the detector consisted of 4HCB single crystald. The size of the 4HCB crystal used in experiments was 4 mm x 4 mm x 2 mm. The 4HCB crystal was mounted on an ABS board. Signal readout wires were connected to both sides of the 4HCB crystal with carbon paste. The experiment was performed in the PH2 course of HIMAC. The energy of the ¹²C beam was 290 MeV/u. The beam intensity was tuned from 10⁸ particles per second (pps) to maximum. Beam size of ¹²C was ∼1 cm at the detectors. Maximum applied voltage to the 4HCB detector was 800 while the during the measurements. As a result, we succeeded measurement of induced charge by carbon beam irradiation with the organic detector. In addition, Bragg curve was measured and LET dependence was observed like other organic semiconductors detectors. (author)