Pulse shape analysis of induced charges in a segmented germanium detector by using the weighting potential method

Abstract

We employed a pulse shape analysis to extract information for the interaction position of gamma rays in a 25-fold segmented germanium detector. We simulated the pulse shapes of the central cathode as well as those of the anode for various depths by using the weighting potential method. By developing a 90degrees Compton spectrometer with collimators on both the incidence and the exit sides, we measured the pulse shapes for the two interaction points (x, y, z) = (2.5 cm, 2.5 cm, 0.5 cm) and (2.5 cm, 2.5 cm, 1.0 cm). The experimental pulse shapes were compared with the ones simulated by using a Monte Carlo technique and the weighting potential method. We suggest that a rise-time correlation between the anode and the central cathode signals, T-90(anode) - T-50 (cathode), can be used as a figure of merit to determine the depth (z) of an interaction point given an in-plane position (x, y). We show that the simulated rise-time correlation is in good agreement with the experimental one.