Energy calibration of thin plastic scintillators using Compton scattering of gamma rays

We are testing a plastic detector prototype to observe cosmic rays of GeV level. The energy deposit in the detector is important to know the composition of the particles which reach on the ground. We use compton scattering of RI to calculate the energy deposit of thin plastic scintillators. The experimental values are compared with Geant4 simulation results. Polystyrene based scintilltor of 1cm thickness is connected to PMT and the DAQ device including an 100MHz oscillator. An analog waveform is converted to 1024 FADC counts. Prototype system consist of two scintillators and their energy deposits is investigated for several different arrangements. In this proceeding, we will show the result of energy calibration of thin plastic scintillators using RI and simulation.