Silicon surface barrier detector for fusion neutron spectroscopy

The usefulness of the intrinsic 28Si(n,α)25Mg and 28Si(n, p)28Al reactions in silicon surface barrier detectors for measurements of ion temperatures in D‐T fusion plasmas and of D‐T fusion neutron flux has been investigated. For a 14‐MeV neutron‐generator narrow‐energy‐line source, the energy resolution (∼1.5%), detection efficiency, and useful count rates have been determined. Based on these results, for a 100‐ms time bin, D‐T plasma ion temperatures from 2 to 6 keV can be determined from the full‐width half‐maximum (FWHM) of the neutron‐induced α spectral lines, with the error estimated to be 25% to 5%, respectively. The maximum intrinsic detection efficiency for a nominal 1500‐μm‐thick detector is ∼6×10−4.