Formation of the isomeric pair194Irm,gin interactions ofαparticles with192Os

Abstract

Cross sections were measured by the activation technique for the nuclear processes ${}^{192}$Os(\ensuremath{\alpha},$d$+$\mathit{pn}$+$\mathit{np}$)${}^{194}$Ir${}^{m}$${}^{,\mathrm{g}}$ up to \ensuremath{\alpha}-particle energies of 39 MeV. From the measured data the isomeric cross-section ratio was deduced as a function of projectile energy. The present experimental data as well as those for the ${}^{194}$Pt($n$,$p$)${}^{194}$Ir${}^{m}$${}^{,\mathrm{g}}$ reaction, given in the literature, were compared with the results of nuclear model calculations using the code talys, which combines the statistical, precompound, and direct interactions. In general, the experimental data were reproduced well by the model calculations, which were done using relatively low values of \ensuremath{\eta} (i.e., ${\ensuremath{\Theta}}_{\mathrm{eff}}/{\ensuremath{\Theta}}_{\mathrm{rigid}}$). The results provide more evidence for the mass dependence of \ensuremath{\eta}. The level density parameter for ${}^{194}$Ir was determined unambiguously.