Averaged cross sections for the reactions 68Zn(n,p)68gCu and 68Zn(n,p)68mCu for a 235U fission neutron spectrum

Making use of the method developed in our laboratory for the simultaneous determination of cross sections leading to both the ground and metastable states, we have measured the 68Zn(n,p)68gCu and 68Zn(n,p)68mCu reactions, using Zn enriched to 99.4% in its isotope 68Zn. The measured cross sections are (15.04±0.35) and (3.69±0.30) μb for the ground and metastable state, respectively. However, a direct determination of the cross section leading to the metastable state gives a value of (4.75±0.38) μb. A possible reason for this discrepancy—which is outside experimental uncertainties—is that some tabulated values used in our calculations for the decay parameters of 68gCu and 68mCu, have either larger than quoted, or unknown systematic, uncertainties.