Interdependence of readout positions (X, Y) for two dimensional patterned position sensitive detectors

摘要

Any dependence of the readout positions (X) to the source vertical displacements (Y) for one dimensional position sensing results in extremely unusual phenomenon for 2D position sensing. In this paper the dependence and the problems based on the dependence is studied for position sensing methods. It is shown that severe dependence exists for one dimensional position sensing using patterned cathodes and the applications of this method must be reviewed for 2D position sensing. Many problems such as resolution degradation, double peak readout, "S" type image distortion and centroid shift for 2D position sensitive detectors are based on this unknown phenomenon. Almost all the patterns, such as the wedge-and-strip, backgammon, chevron and diamond patterns have the dependence along the wedged part. For this part the deviation due to the source vertical displacements varies with the source horizontal positions. This deviation has a maximum value (about 10% of the full length) at the center of the pattern. Using the patterned-cathodes with MWPC (multiwire proportional counters) for 2D position sensing is possible if the wire spacing is a multiple of the single pattern width. Also, these cathodes can be used for two dimensional position sensing, without any limitation, if the readout position in the other dimension is done using drift times of the primary electrons.