The high-purity solid state germanium (HPGe) detectors used in gamma-ray spectroscopy have a typical size of a few centimeters in diameter and a thickness ranging from a few centimeters to a few millimeters. For detectors of such a size, gamma rays may Compton scatter out of the detector's volume before they deposit their entire energy. In this case, the energy reading by the data acquisition system will come up short: the detector records an energy which is only a fraction of the energy of the incident gamma ray.