Spectral measurement of quasi-monoenergetic high-energy neutron field by combination of TOF and Bonner unfolding methods

The spectral neutron fluence was measured by a combination of the TOF method (above keV region) and the Bonner unfolding method (whole energy region), for a 45-MeV quasi-monoenergetic high-energy neutron field. The extrapolated TOF-based spectrum information was used as a default spectrum for the Bonner unfolding method. The Bonner measurements were performed using the
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He-counter based Bonner sphere spectrometer (BSS) and the gold-activation BSS. While both unfolding reproduced reasonable solutions, difference in amount of the low-energy neutrons was observed between the types of BSS.