Upgrade of the Magnetic Proton Recoil (MPRu) spectrometer for 1.5-18 MeV neutrons for JET and the next step

We describe the upgraded Magnetic Proton Recoil fusion neutron spectrometer (MPRu). The original MPR was installed at the JET fusion experiment in 1996, and was designed for diagnosis of the 14-MeV neutron emission in high-power deuterium-tritium (DT) fusion experiments. The goal of the MPR upgrade project is to widen the operational range of the instrument to the full range of fusion relevant neutron energies, 1.5 < En < 18 MeV, to increase its flexibility and to improve the background immunity of the spectrometer's focal plane detector. In this paper we describe how these goals have been achieved by the installation of a new detector hodoscope, based on phoswich scintillators, in combination with state-of-the-art digital data acquisition electronics and enhanced monitoring capabilities. Examples of test results and predicted performance are given.