First results of an active-converter neutron spectrometer

A recoil-proton spectrometer based on a Monolithic Silicon Telescope coupled to a polyethylene converter was developed in the last decade by the authors. It demonstrated to be capable of performing an accurate gamma-neutron discrimination [1], allowing to assess neutron spectra in the energy range 0.4 to 8 MeV. This work presents the study and the development of a novel configuration: a real-time recoil-proton spectrometer. The basic idea is to employ a plastic scintillator as an active converter for measuring the energy released by recoil-protons in the converter itself. By summing, event-by-event, the energy deposited in the active converter and in the downstream silicon telescope, the energy of the impinging neutron is derived online through a simple numerical procedure.