In the framework of the BrightnESS grant, the prototype of a time resolved high resolution neutron detector has been developed for the NMX instrument at European Spallation Source ERIC (ESS). The triple GEM detector with a Gadolinium neutron converter has an active area of 50 x 50 cm2 and an x/y strip readout with 400 μm pitch, which is read out with RD51 VMM3a hybrids and the Scalable Readout System (SRS).
A position resolution of better than 300 μm has been obtained with thermal neutrons. A Cadmium mask with 1.0 mm holes, diagonally separated by 1.3 mm, can be clearly resolved.
The first measurement with the full size demonstrator have been performed using a Copper X-ray beam. The 2D image of the beam is presented below.