Multi-grid-type MSGC with the global–local-grouping function for neutron scattering applications

We are developing a multi-grid-type MSGC (multistrip gas counter) with the global-local-grouping (GLG) readout method for neutron scattering applications. In this method the avalanche charge is divided into two halves. One half charge is used for indicating the coarse position of the incident radiation. And the other half charge is used for locating the detailed position of the incident radiation. The incident position is determined by a two-stage identification method. The advantage of this method is to decrease the number of readout lines. This is crucial for neutron scattering applications since the detector must be operated in a pressure vessel. The drawback of the GLG method is to decrease the charge by 50% and to increase the detector capacitance. However, the total capacitance viewed by a preamplifier is not only the detector capacitance. Actually, when the pressure vessel is used the feedthrough connector inevitably adds a certain amount of capacitance. Thus the drawback of the GLG method is somewhat relieved. We have developed a 6.4 cm × 6.4 cm multi-layer GLG-MSGC plate with Toshibaʹs Au/Ti multi-layer technology. Anode pitch and cathode pitch were selected to be 0.8 mm, a value well suited for neutronic applications. The plate was operated successfully and both the local and the global position identification could be verified. A signal rise time of 400 ns was measured for thermal neutrons.