Measurements of neutron capture cross sections on ${}^{70}\mathrm{Zn}$ at 0.96 and 1.69 MeV

The cross sections of the ${}^{70}\mathrm{Zn}\left(n,\gamma \right){}^{71}\mathrm{Zn}^{\mathrm{m}}\left(T_{1/2}=3.96\pm 0.05\text{−}\mathrm{h}\right)$ reaction have been measured relative to the ${}^{197}\mathrm{Au}\left(n,\gamma \right){}^{198}\mathrm{Au}$ cross sections at 0.96 and 1.69 MeV using a ${}^7\mathrm{Li}\left(p,n\right){}^7\mathrm{Be}$ neutron source and activation technique. The cross section of this reaction has been measured for the first time in the MeV region. The new experimental cross sections have been compared with the theoretical prediction by talys-1.6 with various level-density models and $\gamma$-ray strength functions as well as the tendl-2015 library. The talys-1.6 calculation with the generalized superfluid level-density model and Kopecky-Uhl generalized Lorentzian $\gamma$-ray strength function predicted the new experimental cross sections at both incident energies. The ${}^{70}\mathrm{Zn}\left(n,\gamma \right){}^{71}\mathrm{Zn}^{\mathrm{g}+\mathrm{m}}$ total capture cross sections have also been derived by applying the evaluated isomeric ratios in the tendl-2015 library to the measured partial capture cross sections. The spectrum averaged total capture cross sections derived in the present paper agree well with the jendl-4.0 library at 0.96 MeV, whereas it lies between the tendl-2015 and the jendl-4.0 libraries at 1.69 MeV.

Figure 1

Neutron flux energy spectra $\phi \left(E\right)$ from the ${}^7\mathrm{Li}(p,n_0){}^7\mathrm{Be}$ and ${}^7\mathrm{Li}(p,n_1){}^7\mathrm{Be}$ reactions at (a) $E_p=2800\pm 20\mathrm{keV}$ (b) $E_p=3500\pm 20\mathrm{keV}$ obtained from the code epen.

Figure 2

The schematic of the experimental setup.

Figure 3

Detection efficiency calibration curve of the HPGe detector for the $(1\times 1)-{\mathrm{cm}}^2$ source placed at a distance of 1 cm from the detector. The error bar for the uncertainty due to counting statistics is within the symbol.

Figure 4

Excitation functions of the ${}^{70}\mathrm{Zn}\left(n,\gamma \right){}^{71}\mathrm{Zn}^{\mathrm{m}}$ cross sections measured in this paper, evaluated in tendl-2015 (solid line) as well as calculated by talys-1.6 with five different $\gamma$-ray strength functions (strengths 1–5) with the level-density models: (a) ldmodel1 (b) ldmodel2, (c) ldmodel3, (d) ldmodel4, and (e) ldmodel5. See the text for the details of these $\gamma$-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 5

Excitation functions of the ${}^{70}\mathrm{Zn}\left(n,\gamma \right){}^{71}\mathrm{Zn}^{\mathrm{g}+\mathrm{m}}$ cross sections derived in the present paper, evaluated in tendl-2015 and jendl-4.0 as well as calculated by talys-1.6 with the generalized superfluid level-density model (ldmodel3) and the Kopecky-Uhl generalized Lorentzian $\gamma$-ray strength function (strength 1). The derived present cross sections are $(p,n_0)$ neutron flux energy spectrum averaged, whereas the evaluated and calculated cross sections are for monoenergetic neutrons.