A new M-MSGC readout method and front-end ASIC development

A multi-grid-type microstrip gas chamber (M-MSGC) is being developed for a new spallation neutron source in Japan. In order to determine incident neutron positions, we plan to use an induced charge through floating pads on the M-MSGC. However, the induced charge spreads over several readout strips and a compact centroid calculation method was used to determine the position. At the same time, we need to reduce the number of interconnections through the gas vessel. For these purposes we are developing a new encoding readout method. The principle of the encoding method is based on a charge division method. Analog ASICs were developed that could encode up to 200 positions. Another encoding method is proposed using analog–digital–analog conversion, which showed a capability to encode more than 940 channels.