New concept of CZT-based hand-held radioisotope identifier.

Radiation dose can be determined with the radiation dosimeter. Recently, hand-held radioisotope identifier is being developed by many researchers to measure the radiation dose and to determine the type of the radioisotope. New design concept of the radioisotope identifier is introduced in this work. In this design, one can measure the radiation dose and the type of the radioisotope, and one can also determine the direction where the radiation comes. The hand-held radioisotope identifier is based on cadmium zinc telluride (CZT) detector. The detection principle is from the change of the energy spectrum as the direction of the incident radiation is varied. EGSnrc Monte Carlo simulation is done to calculate the energy spectrum of the CZT detector, and the result is compared with the measured one. The energy spectra are calculated when the gamma-ray is incident on the detection at different directions. The simulation results show the change of the spectrum shape as the incident radiation comes from different directions. The calculation is also done with different radiation energies and detector sizes. A prototype radioisotope identifier is being developed at Korea Atomic Energy Research Institute (KAERI). This work would be helpful to develop next generation radiation dosimeter.