Position readout of MSGC by position encoding into signal pulses

Abstract

We are currently developing a compact readout method for MSGCs based on a fast ADC system and position encoding in signal waveforms. In this method signals from MSGC are recorded and digitally analyzed to give an incident position of individual signals. Signal shapes are varied with the incident position of the MS plate. Both x and y axes can be encoded into one pulse signal for later analysis in the digital signal section. To realize this principle, first we have built a special type of MS plates. The MS plate consists of anode strips, cathode electrodes, and grid electrodes between the anode and the cathode. No backside electrode is required for two dimensional position sensing. After simulation calculations about ion collection, several prototype MS plates were fabricated. A test detector has shown a photopeak for 5.9 keV X-rays. The principle of the position detection has been checked using a fall time measurement of shaped signal pulses. Further development of the signal decoding process is being performed.