Energy dependence of the neutron capture cross section on ${}^{70}\mathrm{Zn}$ near the inelastic scattering threshold

The ${}^{70}\mathrm{Zn}\left(n,\gamma \right){}^{71}\mathrm{Z}{\mathrm{n}}^{\mathrm{m}}$ ($T_{1/2}=3.96\mathrm{h}$) cross section has been measured at $0.40\pm 0.15\mathrm{MeV}$ and $0.70\pm 0.10\mathrm{MeV}$ using a ${}^7\mathrm{Li}{\left(p,n\right)}^7\mathrm{Be}$ neutron source. The energy of proton energy of neutron energy spectrum code was used to calculate the neutron energy spectrum, and the ${}^{197}\mathrm{Au}{\left(n,\gamma \right)}^{198}\mathrm{Au}$ reaction was used as monitor reaction. Detailed uncertainty analysis has been performed, and the newly measured cross sections are reported with their uncertainties and correlation coefficients. The energy dependence seen in the cross sections measured in the present work and in the previous work at higher energies has been compared with the theoretical model prediction with various level density models and γ-ray strength functions. Model code dependence of the prediction is also discussed.

Figure 1

Neutron flux energy spectrum φ($E$) from the ${}^7\mathrm{Li}{\left(p,n_0\right)}^7\mathrm{Be}$ reaction at $E_p=2.25\pm 0.02\mathrm{MeV}$ obtained from the code EPEN [12].

Figure 2

Neutron flux energy spectrum φ($E$) from the ${}^7\mathrm{Li}{\left(p,n_0\right)}^7\mathrm{Be}$ and ${}^7\mathrm{Li}{\left(p,n_1\right)}^7\mathrm{Be}$ reaction at $E_p=2.60\pm 0.02\mathrm{keV}$ obtained from the code EPEN [12].

Figure 3

Excitation functions of the ${}^{70}\mathrm{Zn}\left(n,\gamma \right){}^{71}\mathrm{Z}{\mathrm{n}}^{\mathrm{m}}$ cross sections measured by us, evaluated in TENDL-2015 (solid line) as well as predicted by TALYS-1.8 with eight different γ-ray strength functions (PSF-1–8) and the level density models (LDM-1–6): (a) LDM-1, (b) LDM-2, (c) LDM-3, (d) LDM-4, (e) LDM-5, and (f) LDM-6. See the text for the details of these γ-ray strength functions and level density models. The experimental cross sections are ($p,n_0$) neutron flux energy spectrum averaged, whereas the evaluated and calculated cross sections are for monoenergetic neutrons.

Figure 4

Comparison between predictions of ${}^{70}\mathrm{Zn}\left(n,\gamma \right){}^{71}\mathrm{Z}{\mathrm{n}}^{\mathrm{m}}$ reaction cross sections by TALYS-1.6 and TALYS-1.8 with two different γ-ray strength functions (PSF-3 and PSF-4) and the level density model (LDM-3) respectively.