Validation of selected (n,2n) dosimetry reactions in IRDFF-1.05 library

Spectrum-averaged cross sections (SACS) have been measured in the reference ²⁵²Cf(sf) neutron field for the following high-threshold (n,2n) neutron dosimetry reactions since they are especially important due to the high threshold which allows validation of upper parts of prompt fission neutron spectrum. This work includes 59Co(n,2n)58Co, 197Au(n,2n)196Au, ¹⁶⁹Tm(n,2n)¹⁶⁸Tm, ⁵⁵Mn(n,2n)⁵⁴Mn, ⁹³Nb(n,2n)^92 mNb and ⁸⁹Y(n,2n)⁸⁸Y and for the ⁵⁹Co(n,p)⁵⁹Fe threshold reactions. SACS were inferred from experimentally determined reaction rates by gamma spectrometry using a semiconductor high-purity germanium detector to measure irradiated samples. Measured reaction rates agree within quoted uncertainties with those calculated from the IRDFF-1.05 library, except for the reaction ⁵⁵Mn(n,2n)⁵⁴Mn, for which the measured value is underestimated by 16%. For this reaction the ENDF-B/VII.1 evaluation agrees with measured reaction rate within uncertainties.