Improvement of the imaging resolution for a Compton camera by determination of the interaction depth in a 25-segmented germanium detector

The imaging resolution in a Compton camera depends mainly on the position uncertainty, which is affected by the size of electrodes in a detector. Therefore, if any other method is not used for the reduction of the position uncertainty, the imaging resolution is limited by the size of electrodes. Recently, we have developed a Compton camera consisting of a double-sided silicon strip detector (DSSD) and a 25-segmented germanium detector (25-SEGD). The 25-SEGD has an active volume of 5 x 5 x 2 cm³. We have performed measurement for determination of the interaction depth in the 25-SEGD using the pulse shape analysis. After getting a rise-time correlation between the anode and the segment, we obtained a relation formula between the rise-time of the detector signal and the depth derived from the decay equation of gamma-ray in the detector. This decay formula has been used for the determination of interaction depth. As a result of applying the relation function to image reconstruction, we could improve the imaging resolution.