A large-area ceramic GEM neutron detector with high efficiency at CSNS

With the development of neutron sources towards higher fluxes, detectors require higher counting rates to remain applicable, especially for direct-beam or small-angle scattering measurements. Gas electron multiplier (GEM) detectors have emerged as a suitable candidate owing to their high counting rate capability, high spatial resolution, and feasibility for large-area fabrication. This paper presents a prototype multilayer boron-coated ceramic GEM detector developed at the China Spallation Neutron Source (CSNS). The ceramic GEM, originally developed by the Institute of High Energy Physics (IHEP), was employed to reduce neutron scattering owing to its high transmittance and low self-scattering. To date, a multilayer ceramic GEM detector has been fabricated and tested. The detector features an active area of 200.7 mm × 200.7 mm, a spatial resolution better than 2.5 mm (full width at half maximum, FWHM), a maximum system counting rate exceeding 1.1 MHz, and a neutron detection efficiency of approximately 43 ± 2% at a wavelength of 4.8 Å. Moreover, the detector exhibits good imaging capability and can be used for large-volume imaging. Its excellent performance makes it well suited for the Very Small Angle Neutron Scattering (VSANS) instrument and the Energy-resolved Neutron Imaging Instrument (ERNI) at CSNS.