Characteristics of gamma-ray energy and timing spectra for a planar-type segmented germanium detector

We investigated the performance of a plannar-type germanium detector with 25 segments as a position-sensitive gamma-ray spectrometer. Detector characteristics, such as the energy resolution, the photopeak efficiency and the peak-to-total (P/T) ratio, were studied on the energy spectrum. The P/T ratio of the energy spectrum for the anode varied with the degree of the coincidence fold required between segments. The P/T ratio of the present detector proves to be superior to that of conventional coaxial-type germanium detectors or even Compton-suppressed detectors when three-fold coincidence is required between three segments only. It is suggested that the energy spectrum can be observed to be nearly free from a Compton background if an appropriate coincidence fold is required between segments. Another energy spectrum, reconstructed from summing two or more cathode spectra, showed an interesting effect due to incomplete charge collection. The time difference spectra for cathodes contained useful information on the depth profiles for an interaction point