Measurements of the cross-section of 111Cd(n,n′)111mCd reaction for 241Am/Be neutrons

The cross-section of the Cd-111(n,n ')Cd-111m reaction was measured with Am-241/Be neutrons using a natural cadmium target (Cd-nat). The neutron fluence and mean neutron energy of the source were determined using the ISO 8529-1 neutron spectrum and the known cross-sections of the monitor reaction In-115(n,n ')(115)mIn. In order to measure the poor gamma-ray activity of the reaction products, an HPGe detector with 70% detection efficiency surrounded by an adequate graded shield was applied. The efficiency calculations for the detector were performed using standard point calibration sources and the EFFTRAN efficiency code. Using the measured values of the neutron flux and the induced gamma-ray activity of 111mCd, the cross-section of the Cd-111(n,n ')Cd-111m reaction at the average neutron energy of 4.05 MeV was found to be 361 +/- 21 mb. An estimation of the contribution to the total cross-section by the accompanied reactions Cd-110(n,gamma)Cd-111m and Cd-112(n, 2n)Cd-111m was achieved and the related cross-sections were found to be 0.16 mb and 8.99 mb, respectively.