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.