Measurement of the MACS of at kT=30 keV as a test of a method for Maxwellian neutron spectra generation

Measurement of the Maxwellian-Averaged Cross-Section (MACS) of the Ta ( n , γ ) 181 reaction at kT=30 keV by the activation technique using an innovative method for the generation of Maxwellian neutron spectra is presented. The method is based on the shaping of the proton beam to produce a desired neutron spectrum using the 7Li(p,n) reaction as a neutron source. The characterization of neutron spectra has been performed by combining measured proton distributions, an analytical description of the differential neutron yield in angle and energy of the 7Li(p,n) reaction, and with Monte Carlo simulations of the neutron transport. A measured value equal to 815±73 mbarn is reported for the MACS of the reaction Ta ( n , γ ) 181 at kT=30 keV. The MACS of the reaction Au ( n , γ ) 197 provided by KADoNiS has been used as a reference.