Growth of a CsI:CO₃ crystal and the measurement of the light response of the CsI:CO₃ crystal to protons

We grew a CSI:CO₃ single crystal with a concentration of CO ₃ of 0.02 mole percent by using the Czochralski method. We cut the crystal into a size of 10.3 mm in diameter and 10.9 mm in length. We investigated the luminance characteristics of the CSI:CO₃ crystal including the fluorescence decay time, the energy resolution and the pulse height spectrum, by using a 661-keV γ-ray source. The light response of the CsI:CO₃ crystal was measured for a proton beam in the energy range from 11 MeV to 36 MeV by using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS) with different thicknesses of aluminum degraders. We estimated the energies of the proton beam after passing through the degraders and 190-cm-thick air by using a Monte Carlo simulation based on the Geant4 simulation toolkit. We show that the scintillation response of the CsI:CO₃ crystal to a proton beam in the above energy range is approximately linear.