High-resolution cross section measurements for neutron interactions on $^{89}$Y with incident neutron energies up to 95 keV

Abstract

The cross section of the $^{89}$Y(n, $\gamma$) reaction has important implications in nuclear astrophysics and for advanced nuclear technology. Given its neutron magic number N = 50 and a consequent small neutron capture cross section, $^{89}$Y represents one of the key nuclides for the stellar s-process. It acts as a bottleneck in the neutron capture chain between the Fe seed and the heavier elements. Moreover, it is located at the overlapping region, where both the weak and main s-process components take place. $^{89}$Y, the only stable yttrium isotope, is also used in innovative nuclear reactors. Neutron capture and transmission measurements were performed at the time-of-flight facilities n_TOF at CERN and GELINA at JRC-Geel. Resonance parameters of individual resonances were extracted from a resonance analysis of the experimental transmission and capture yields, up to a neutron incident energy of 95 keV. Even though a comparison with results reported in the literature shows differences in resonance parameters, the present data are consistent with the Maxwellian averaged cross section suggested by the astrophysical database KADoNiS.

Appendix A: List of mishaps in evaluated data libraries

In JENDL-5.0 [25]

• 1. The neutron width $\Gamma _n$ for the 7483 eV resonance is given as 0.654 eV and should be 65.4 eV.

In ENDF [27] and JEFF-3.3 [26]

• 1. There is a group of resonances, i.e. the resonances at 51703, 52035, 55330, 56582, 62459, 69070, 74490, 75107, 75977, 83180, 85210, 89173, and 94125 eV, with neutron widths that are reduced by a factor 1000, e.g. the $\Gamma _n$ for the 51703 eV resonance is given as 0.06 eV and should be 60 eV.

• 2. The energy for the 53865 eV resonance is given as 52865 eV.