Proton beam energy monitoring with radiation-hard crystal scintillators

Monitoring of the energy profiles of protons in different beam configurations is important not only for understanding the characteristics of proton beam but also for understanding the light output response of a scintillation crystal. The energy profile of a proton beam was measured with several types of crystal scintillators by using 35- and 45-MeV proton beams from the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences. Scintillation crystals of BGO, LYSO and GSO were used for the energy measurement of the proton beam. The pulse height spectrum and the energy resolution were measured for each crystal and compared with one another. The best energy resolution was 3 % FWHM with the GSO crystal. Different thicknesses of energy degraders were used with the 35- and the 45-MeV proton incident energies to measure the light output response function of the BGO crystal.