New measurement of residues from ${}^7\mathrm{Li}+{}^{\mathrm{nat}}\mathrm{Ta}$ reaction within 4–6.5 MeV/nucleon: Production yield for ${}^{183}\mathrm{Os}$

Exploration of reaction dynamics of the weakly bound heavy-ion interaction with an intermediate or heavy mass target in the low energy range has been a subject of interest over the past decades; however, different modes of fusion such as breakup fusion, incomplete fusion, and transfer phenomena observed experimentally are not yet fully understood. Experimental studies are therefore essential to address the problem. In this article, we report a new set of cross-section data of the residues produced in the weakly bound ${}^7\mathrm{Li}$ induced reaction on ${}^{\mathrm{nat}}\mathrm{Ta}$ within the 27–45 MeV energy range. Along with the major yield of ${}^{\text{183g+m}}\mathrm{Os}$, production of ${}^{\text{180m}}\mathrm{Hf}$ and ${}^{183}\mathrm{Ta}$ are also observed up to $\sim 35\mathrm{MeV}$, which is possibly an indication of the incomplete fusion mechanism or breakup-transfer phenomena. The trend of the isomeric cross-section ratio of ${}^{183}\mathrm{Os}$ indicates the role of angular momentum and spin distribution besides the excitation energy, and is interpreted by theory. The optimized production parameters and yields of ${}^{\text{183g,m}}\mathrm{Os}$ are assessed.

Figure 1

A $\gamma$-ray spectrum of the 35.3 MeV ${}^7\mathrm{Li}$ activated Ta-foil collected after 47 min of the EOB, characteristics $\gamma$-ray peaks are shown in keV.

Figure 2

Comparison of the experimental cross-sections of ${}^{\text{183g}}\mathrm{Os}$ with the theoretical estimations from pace4, alice14, and empire3.2.2 with different level density parameters.

Figure 3

Comparison of the experimental cross-sections of ${}^{\text{183m}}\mathrm{Os}$ with the theoretical estimations from alice14 and empire3.2.2 with different level density models.

Figure 4

Half-life estimations for ${}^{\text{180m}}\mathrm{Hf}$ and ${}^{183}\mathrm{Ta}$.

Figure 5

Comparison of the experimental cross-sections of ${}^{\text{180m}}\mathrm{Hf}$ with empire3.2.2 with different level density models.

Figure 6

Same as in Fig. 5 for ${}^{183}\mathrm{Ta}$

Figure 7

Abridged decay scheme of ${}^{\text{183g,m}}\mathrm{Os}$ residues with energy levels marked in keV.

Figure 8

Comparison of experimental ICR values of ${}^{183}\mathrm{Os}$ with the theoretical estimations from empire3.2.2.

Figure 9

Production yield of ${}^{\text{183g+m}}\mathrm{Os}$ at distinct bombarding energies.