Development of a ceramic gas-electron-multiplier neutron detector prototype with a large sensitive area

The rapid growth of neutron flux has driven the development of ³He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutron Source (CSNS). Position-sensitive neutron detectors with a high counting rate and large area play an important role in the instruments performing neutron measurements in or close to the direct beam. The ceramic gas-electron-multiplier (GEM) detector serves as a promising solution, and considerable work has been done using the small-area GEM neutron detectors. In this article, we designed and constructed a detector prototype utilizing ceramic GEM foils with an effective area of about 307 mm×307 mm. To evaluate and investigate their basic characteristics, the Monte Carlo (MC) tool FLUKA was employed and several neutron beam tests were conducted at CSNS. The simulated spatial resolution was basically in agreement with the measured value of 2.50±0.01 mm (FWHM). The wavelength spectra measurement was verified through comparisons with a commercial beam monitor. In addition, a detection efficiency of 4.7±0.1% was achieved for monoenergetic neutrons of 1.59 Å wavelength. This is consistent with the simulated result. The results indicate that the large-area ceramic GEM detector is a good candidate to implement neutron beam measurements. Its efficiency can be improved in a cascading manner to approach that reached by traditional ³He detectors.