TCD (Triple Charge Division): a novel centroid finding method

Abstract

A Triple Charge Division (TCD) centroid finding method that uses a zigzag pattern for triple dividing of the cathode plane is introduced for medium length position sensitive detectors. Although the central area of the triple charge division pattern is the widest, both side areas have major roles in position sensing. For the same resolution and linearity, the active region of this pattern is wider than conventional cathode patterns. For the same width, the linearity of TCD centroid finding is much better than position sensing with other patterns. Predicted effects of truncated zigzags are confirmed by experimental results for the central points of the TCD pattern. A new readout method (graded charge division) is introduced for TCD centroid finding because of different distributions of induced charges on the central area and both sides. This readout method is a combination of charge division readout and position grading for three serial segments. The TCD centroid finding method and graded charge division readout were tested using double size, triple charge division patterns (200 mm and 80 mm). Spatial resolution of about 1% of the detector length was achieved.