High-energy resolution spectrometer with proportional counter and Si-detector telescope type for 14 MeV neutrons in plasma diagnostics

A new type of fast neutron spectrometer composed of a CH4 proportional coun ter and a Si semiconductor detector which is called the counter telescope t ype was constructed for plasma-temperature diagnostics. The counting gas CH 4 is used as a converter of neutrons to protons. Since the energy loss of t he proton in the converter CH4 can be fairly precisely measured with the pr oportional counter, the energy resolution for the proton is high, so that a good energy resolution for neutrons is obtained. The energy resolution of the spectrometer itself excluding the energy spread of the D-T 14 MeV neutr ons was 1.7% which seems to be the best so far, and the detection efficienc y was 1 x 10(-6). If better energy resolution is preferable, even 0.5% is o btained and the efficiency in this case is 4 x 10(-8). (C) 1999 Elsevier Sc ience B.V. All rights reserved.