Development et mise au point en pile d'une nouvelle technique de spectromètrie neutronique basée sur le choc (n, p)

A new proton recoil spectrometer, for in-core neutron spectrum measurements, is described.
The spherical on cylindrical proportional counters, routinely used
energy interval from a few keV up to about 1.5 MeV. The described spectrometer was conceived to determine the neutron spectrum above this energy limit. Attention was paid to keep the lower validity energy limit sufficiently small as to obtain a large energy interval overlapping with the existing spectra. A hydrogeneous target and a surface barrier detector are the main parts of
the spectrometer. A small proportional counter is inserted between the two
as to eliminate background pulses in the solid state detector, due to gamma
radiation or competitive reactions with the silica of the detector. A filling of argon at low pressure completes the spectrometer. After the performances
of the spectrometer were tested in the BRl thermal graphite column by means of the ⁶Li (n,α)t reaction, a proton recoil spectrum was measured in the fast assembly mounted in BRl. The responses of both counters are analysed in a bidimensional configurationon by means of a two-parameter analyser.