We have studied the decay of actinide nuclear system ${}^{254}$Fm${}^{*}$ formed in ${}^{11}$B  $+$ ${}^{243}$Am reaction using the dynamical cluster decay model (DCM), with choices of spherical, quadrupole deformation ${\beta }_2$ alone and higher multipole deformations ${\beta }_2$–${\beta }_4$. For ${\beta }_2$ deformations, the optimum orientations ${\theta }_i^{\mathrm{opt}}$ are used whereas for higher multipole deformations the compact orientations ${\theta }_i^c$ of decaying fragments are taken in to account. Besides static-${\beta }_2$ deformations, the effects of dynamical-${\beta }_2$ deformations are also explored. The calculated cross sections find excellent agreement with the available experimental data with spherical as well as deformed choices of fragmentations, enabling us to account for the role of important nuclear deformation effects in the ${}^{11}$B-induced nuclear reaction. Spontaneous decay of ${}^{254}$Fm with cold elongated configuration and optimum orientation is also worked out. The mass distributions of excited fermium isotopes in the neighborhood of ${}^{254}$Fm${}^{*}$ are also explored. In addition, the roles of temperature, angular momentum, and fission fragment anisotropies are investigated in the context of the chosen reaction.

• Received 12 July 2012

DOI:https://doi.org/10.1103/PhysRevC.86.064610