Speaker
Gabriele Croci
(Universita & INFN, Milano-Bicocca (IT))
Description
The research of valid alternatives to 3He detectors is fundamental for the detector affordability of new neutron spallation sources like the European Spallation Source (ESS). In the case of ESS it is also essential to develop high-rate detectors that can fully exploit the increase of neutron flux relatively to present neutron sources. One of the technologies fulfilling these requirements is the Gas Electron Multiplier (GEM) coupled to boron converter layers. Some developments and improvements are needed in order to make this detector technology mature to be really competitive. The detector has to be able to sustain a high rate thermal neutron flux, must have a high efficiency (similar to 3He) and the resolution of FWHM of diffraction peaks must comparable to those of 3He systems. This presentation shows recent improvements obtained in the last two years in these directions. The neutron rate capability was tested under a very high flux thermal neutron beam (108 n/cm2*s) showing no decrease of performances up to several MHz/cm2; neutron diffraction experiments with a GEM detector took place (for the first time) on the INES instrument at ISIS, showing results directly comparable to those of 3He tube; a new prototype of higher efficiency boron GEM based detector was realized and recently tested showing an efficiency between 15% and 20% to 25 meV neutrons. This prototype represents a further step towards the realization of high efficiency thermal neutron GEM based detectors.