Diffraction measurements with a boron-based GEM neutron detector

The research of reliable substitutes of He-3 detectors is an important task for the affordability of new neutron scattering instrumentation for future spallation sources like the European Spallation Source. GEM (Gas Electron Multiplier)-based detectors represent a valid alternative since they can combine high-rate capability, coverage of up to 1 m(2) area and good intrinsic spatial resolution (for this detector class it can be better than 0.5 mm). The first neutron diffraction measurements performed using a borated GEM detector are reported. The detector has an active area of 10 x 5 cm(2) and is equipped with a borated cathode. The GEM detector was read out using the standard ISIS Data Acquisition System. The comparison with measurements performed with standard He-3 detectors shows that the broadening of the peaks measured on the diffractogram obtained with the GEM is 20-30% wider than the one obtained by He-3 tubes but the active area of the GEM is twice that of He-3 tubes. The GEM resolution is improved if half of its active area is considered. The signal-to-background ratio of the GEM is about 1.5 to 2 times lower than that of He-3. This measurement proves that GEM detectors can be used for neutron diffraction measurements and paves the way for their use at future neutron spallation sources. Copyright (C) EPLA, 2014