Development of a novel low-pressure detector with high position and time-of-flight resolution for thermal neutron detection

The pulsed high-flux neutron source ESS, in synergy with advanced neutron optics and spectrometers, will require imaging detectors with better resolution and faster response than presently available. Thus in this work, which is part of a project of the Hahn-Meitner-Institut (HMI), a novel neutron detector has been developed. In the central detector plane a composite foil converter (157Gd/CsI) is located, emitting, after neutron capture and subsequent emission of conversion electrons, a detectable cluster of low-energy electrons. In two adjacent low-pressure gas gaps, sandwiched between fourfold segmented micro-strip gas chamber (MSGC) plates on each side, the clusters are pre-amplified in parallel-plate mode and further in the strong alternating fields between the micro-strips. The advanced micro-strip design is made in multilayer technology on a robust glass substrate. Two closely spaced electrode planes are used for two-dimensional position readout. The expected position resolution is 0.1 - 0.3 mm and the time-of-flight resolution for thermal neutrons is less than 4 ns. Within the scope of this work all electrodes have been optimised for low-pressure, two-stage amplification by a comprehensive modelling. For the second coordinate plane a new electrode structure was found, which gives fast and high signals