Abstract
In recent years, Gas Electron Multiplier (GEM) neutron detector has been developing towards high spatial resolution and high dynamic counting range. A novel concept of the Al stopping layer was proposed to enable the detector to achieve sub-millimeter (sub-mm) spatial resolution. The neutron conversion layer was coated with the Al stopping layer to limit the emission angle of ions into the drift region. The short track projection of ions was obtained on the signal readout board, and the detector would get good spatial resolution. The spatial resolutions of the GEM neutron detector with Al stopping layer were simulated and optimized based on Geant4GarfieldInterface. When Al stopping layer was 3.0 μm thick, drift region was 2 mm thick, strip pitch was 600 μm, and digital readout was employed. The spatial resolution of the detector was 0.76 mm, and the thermal neutron detection efficiency was about 0.01%. Thus, the GEM neutron detector with a simple detector structure and a fast readout mode was developed to obtain a high spatial resolution and high dynamic counting range. It could be used for the direct measurement of a high-flux neutron beam, such as Bragg transmission imaging, very small-angle scattering neutron detection and neutron beam diagnostic.
