Response and calibration of organic scintillators for gamma-ray spectroscopy up to 15-MeV range

We present a calibration method for an organic scintillator suitable for gamma energies of up to 15 MeV. We use a combination of experiments and simulations to identify prominent features in the light output spectra to provide an accurate calibration method over this energy range. Gamma energies in the range of 0.511 MeV to 15.1 MeV were used to perform two separate calibrations to the measured light output expressed in the units of electron equivalent energy. The first method strictly uses the well-known technique of identifying the Compton edges, while the second utilizes a combination of Compton edges and double escape peaks for several gamma energies. We performed a least-squares test to the high end of the light output spectra for a 15.1 MeV gamma ray to assess the accuracy of the two methods. The calibration technique that employs a combination of Compton edges and escape peaks yielded a significant improvement in accuracy when compared to a calibration that relies solely on the use of Compton edges.