Charge Loss Correction in a High-Purity Germanium Double-Sided Strip Detector

Abstract

One fundamental design issue in the HPGe double-sided strip detector (DSSD) is the gap between strips, which makes up 1/6 of the 3 mm strip pitch in the University of Michigan (UM) strip detector. While a wide gap between strips reduces interstrip capacitance, thereby improving energy resolution, it also results in measurable charge loss in the UM strip detector. Charge loss on either detector side for a single interaction in a Compton sequence may eliminate that sequence from being included in image reconstruction. A method for charge loss correction is described for interactions which fall in detector gaps. Over the energy range 60-1274 keV, charge loss correction increases photopeak counts by 15% on the anode side and 5% on the cathode side. Charge loss correction can be accomplished nearly as well when a second interaction falls beneath an adjacent strip. With the prevalence of close interactions in HPGe, the method is effective for ~87% of all gap interactions at 662 keV. Furthermore, the method is not computationally expensive, so it is suitable for real-time imaging application.