The Use of the Reaction ⁹³Nb(n,n')^93mNb for Fast Neutron Flux Measurement

A method for high fast neutron flux measurement using the reaction ⁹³Nb(n,n')^93mNb was tested. The method is based on measurement of niobium x rays. An average cross section over a measured ²⁵²Cf neutron spectrum was calculated and found to be = 1.88 ± 3% b. Here, ^93mNb has a metastable level at 30 keV with a half -life of 13.6 yr. The branching ratio of the gamma rays emitted from this level was found to be ∼4%. The measurement was done by measuring the 16.52 + 16.62 keV niobium x-ray lines with an Si(Li) detector.