Development of an imaging microstrip gas chamber with a 5 cm × 5 cm area based on multi-chip module technology

Abstract

We have developed a two-dimensional MicroStrip Gas Chamber (MSGC) with a 5 cm × 5 cm detection area based on Multi-Chip Module (MCM) technology. It has a 17 μm thin substrate, 254 anodes, and 255 back strips both with a 200 μm pitch. The MSGC was mounted on a large Pin Grid Array (PGA) package having more than 500 pins, which allowed us to readily connect a large number of signals of an imaging MSGC with readout electronics. In this article, we report on the capability of the MSGC as an X-ray imaging detector operated near an intense X-ray source. In order to get stable operation at high X-ray intensity, we found one solution using a ∼ 20 μm substrate and a surface resistivity of ∼ 10 15 Ω/square. The control of the surface resistivity was carried out by coating the polyimide substrate with organic titanium. This improvement enabled the MSGC to be stably operated for ∼ 10 3 s under a very high counting rate of 10 7 Hz/mm 2. The MSGC is also being operated for several months under medium intensity X-rays from an X-ray generator. In this measurement, high quality digital X-ray images with ∼ 60 μm RMS (Root Mean Square) position resolution were obtained with a simple-readout method of recording only the positions of hit electrodes.