Measurement and analysis of the isomeric cross section ratios for the ${}^{94}\mathrm{Tc}$ nucleus

We report on an isomer yield ratio study of biologically important ${}^{94}\mathrm{Tc}$ following the fusion of the ${}^9\mathrm{Be}+{}^{89}\mathrm{Y}$ system, carried out using the offline $\gamma$-ray spectroscopy in continuation to the online activation method. The incident beam energies considered are above the Coulomb barrier for the present paper. The platypus model in conjunction with a potential model calculation was employed to analyze the data. An agreement in the order of magnitude between the experimental data and the theoretical predictions has been achieved by applying a phenomenological approach. The approach was further tested with isomer yield ratios of ${}^{94}\mathrm{Tc}$ formed through ${}^3\mathrm{He}+{}^{93}\mathrm{Nb}$ reactions. Possible factors that relate to the isomer yield ratios are also presented.

Figure 1

Decay scheme of ${}^{94}\mathrm{Tc}$. The data are taken from Ref. [26], and only partial transitions are shown in the scheme.

Figure 2

Offline coincidence spectra measured from the decay of ${}^{94}\mathrm{Tc}$ nucleus, gated by the (a) 1868.7-keV and (b) and (c) 871.1-keV transitions.

Figure 3

Radioactive decay curves for the (a) ${}^{94}\mathrm{Tc}^g$ and (b) ${}^{94}\mathrm{Tc}^m$ states formed through the ${}^9\mathrm{Be}+{}^{89}\mathrm{Y}$ reaction by using the 916.0- and 1868.7-keV transitions, respectively. See the text for details.

Figure 4

Measured and calculated excitation functions for the complete fusion of the ${}^9\mathrm{Be}+{}^{89}\mathrm{Y}$ system at above barrier energies. The blue dashed line refers to the result from the potential model calculation, assuming direct CF of the projectile-target without breakup. The red line corresponds to the result from the platypus model combined with the potential model calculation, assuming partial contribution (34%) from CF following breakup. The experimental data have been presented in Ref. [23]. See the text for details.

Figure 5

Calculated angular momentum distribution for compound nucleus from CF of the ${}^9\mathrm{Be}+{}^{89}\mathrm{Y}$ system at beam energies of 45.9 and 48.1 MeV. The division of population between the ground and the isomeric states at 45.9 MeV is indicated by the blue and red lines with $J_{\mathrm{eff}}=4\hslash$ and $\delta =0.5$. See the text for details.

Figure 6

The calculated and measured isomer ratios for ${}^{94}\mathrm{Tc}$ formed through the ${}^9\mathrm{Be}+{}^{89}\mathrm{Y}$ system, assuming different $J_{\mathrm{eff}}$'s and $\delta$ values. See the text for details.

Figure 7

(a) The measured and calculated complete fusion cross sections of the ${}^3\mathrm{He}+{}^{93}\mathrm{Nb}$ system at above barrier energies. The experimental data are deduced using cross sections from Ref. [36]. The theoretical curve results from the potential model calculation. (b) The measured [36] and calculated isomer yield ratios for the ${}^{94}\mathrm{Tc}$ using different $J_{\mathrm{eff}}$'s and $\delta$ values. See the text for details.