Enhancement of counting statistics and noise reduction in the forward-scattering detectors on the Vesuvio spectrometer.

Experiments were performed using photon-sensitive detectors, installed on the Vesuvio spectrometer at the ISIS neutron source, in order to improve the detection limit of hydrogen atom in condensed-matter samples and allow a more precise line-shape analysis of the atomic momentum distribution. At present, these detectors measure photons with energies greater than 600 keV in order to avoid the main sources of background. We discuss the advantage in reducing the level of the energy threshold so as to detect high-intensity low-energy prompt-gamma rays emitted after the radiative neutron capture by gold, used as the energy analyser on Vesuvio.