Space charge in ionization detectors and the NA48 electromagnetic calorimeter

The subject of space charge due to positive ions slowly moving in parallel plate ionization chambers is considered. A model for the degradation of the detector response is developed, with particular emphasis on electromagneti c calorimeters. The topics discussed include: (a) the stationary; (b) the t ime dependent cases; (c) the limit of very large space charge, (d) the elec tric held dependence of the electron drift velocity; (e) the effect of long itudinal development of showers; (f) the behaviour of the average reduction s of response; and (g) the non-uniformity of response for different positio ns of the shower axis inside the cell defined by the electrodes. The NA48 c alorimeter is used as application and for comparison of results. (C) 1999 E lsevier Science B.V. All rights reserved.