Energy calibration of NE-213 scintillation counters by δ-rays

An accurate energy calibration of organic scintillation counters by means of γ-rays is described. The position of the Compton edge has been precisely determined comparing measured with calculated spectra. The calculation includes wall and light pipe effects and the influence of channel dependent pulse height resolution. Relations are given for the position of the maximum and the half maximum of a Compton spectrum as a function of the incident photon energy and the resolution of the detector. Results are given with uncertainties smaller than 1 %.