Improving the performance of the MWPC X-ray imaging detector by means of the multi-step avalanche technique

X-ray imaging systems based on conventional MWPC technology and artificial delay line readout techniques have been developed at RAL for several applications over a period of some eight years. Successful as this effort has been, it is now perceived that very limited scope exists for the further improvement of the imaging capability of the standard MWPC design. Attention has therefore been turned to the possibility of exploiting the multi-step avalanche (MSA) system of electron multiplication in this context. Results from a prototype system are presented which show spatial resolution better than that achieved in our MWPC systems with no wire artefacts in the image. The facility for controlling the effective depth of the detector electronically is also demonstrated so offering some alleviation of the parallax problem common to all gaseous X-ray detectors.