Position-sensitive detectors based on carrier drift using a CdTe semiconductor

The current γ-ray imaging system has the disadvantage of a very high cost due to its need for many pixels, amplifiers and control circuits to obtain high resolution. In order to reduce the cost of γ-ray imaging detectors we propose a single-element detector which is able to obtain two-dimensional γ-ray images, and investigate the feasibility of a one-dimensional position-sensitive detector as a first stage. A CdTe semiconductor detector was employed in the single-element position-sensing detector. Because the mobility-lifetime product for electrons is much higher than that for holes, the movement of holes can be neglected and the CdTe detector can be regarded as an electron drift detector. We made a prototype of a simply structured, one-dimensional position-sensitive detector and evaluated its performance. Consequently, it was confirmed that the position-sensitive detector with a single CdTe element and with sub-millimeter resolution was achieved at low cost.