Improving the position resolution of highly segmented HPGe detectors using pulse shape analysis methods

This work presents an approach for determining the interaction position of #gamma# rays in highly segmented HPGe detectors. A precise knowledge of the interaction position enables the effective granularity of the detector to be substantially improved and a calibration of the detector response as a function of position to be performed. An improved position resolution is fundamental for the development of arrays of #gamma# ray tracking detectors. The performance of a highly segmented germanium detector (TIGRE) has been characterised. TIGRE consists of a large volume coaxial high-purity n-type germanium crystal with a 24-fold segmented outer contact. Due to its high granularity and its fast electronics, TIGRE represents a unique example of a tracking detector, having low noise output signals, fast rise time and good energy resolution. In order to calibrate the response of the detector as a function of the interaction position, a dedicated scanning apparatus has been developed and the front surface of the detector has been scanned. The method developed for position determination is based on the digital analysis of the preamplifier signal, whose features are position dependent. A two-dimensional position resolution is accomplished by combining the radial position information, contained in the rise time of the pulse shape leading edge, with the azimuthal position information, carried by the magnitude of the transient charge signals induced in the spectator segments. Utilising this method, a position resolution of 0.6 mm, both radially and along the azimuthal direction, can be achieved in the most sensitive part of the detector. (author)Available from British Library Document Supply Centre- DSC:DXN063787 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo