A study of the spectroscopic performance of a CdTe microstrip detector

Abstract

A study of the spectroscopic performance of a CdTe detector, equipped with a "strip anode" placed between two parallel focusing strips, was carried out. The focusing strips were kept at an intermediate bias voltage with respect to anode and cathode. This configuration increases the intensity and focuses the electric field on the region surrounding the strip anode, thus improving the collection of electrons. The detector was irradiated with a narrow photon beam emitted by a /sup 57/Co source. In the classical configuration, with the photon beam impinging perpendicularly to the cathode plane, the spectroscopic response of this kind of detector looks better than that obtained by the usual "full anode" CdTe detectors, mostly as concerns the photopeak efficiency in the 122 keV energy region. Previous measurements carried out on detectors having the same crystal size, but equipped with a full anode, showed a considerable improvement in spectroscopic performance at 122 keV when the photon beam impinged on the detector at almost grazing angle with respect to the cathode surface. Thus a similar set of measurements was carried out on detectors having strip anode configuration in order to verify their behavior in the same experimental conditions. Unfortunately, no spectroscopic improvement seems to occur in this case at large impinging angle.