Measurement of proton beam energy and flux by using a LYSO crystal

We investigated the beam profiles of the 45-MeV proton beam from the MC-50 cyclotron at Korea Institute of Radiological and Medical Science. We used a 45-MeV proton beam of 0.2-nA beam current to measure the beam energy and flux. The 45-MeV proton beam passed through a 0.2-cm thick aluminum window capping the beam pipe and then was collimated to a 1-mm-diameter beam spot by using a 1-mm aluminum collimator. We examined the dependence of the energy profile of the proton beam on the transverse distance from the beam center by using the LYSO crystal scintillator. Also, the flux of the proton beam was measured with the LYSO crystal scintillator. Accurate information on the energy profile of the beam is important not only for understanding the characteristic of the beam but also for understanding the light output response of a scintillation crystal. From our investigation, the energy profiles of the beam at the near point from the center and some distance points from the center were found to be very different. Thus, it is very important to test the energy profile of the beam at the point where the detector will be located before one performs the beam test for a detector, such as a silicon sensor.