Higher-multipole deformations and compactness of hot fusion reactions

Abstract

The effect of adding the higher-multipole deformations ${\ensuremath{\beta}}_{6}$ and ${\ensuremath{\beta}}_{8}$, and the octupole deformation ${\ensuremath{\beta}}_{3}$ (in addition to quadrupole and hexadecapole deformations ${\ensuremath{\beta}}_{2}$ and ${\ensuremath{\beta}}_{4}$), on the distribution of barriers in orientation degrees of freedom is studied for a ``compact'' configuration of spherical-plus-deformed or deformed-plus-deformed nuclei in hot fusion reactions. Though ${\ensuremath{\beta}}_{3}$ is known to be nonzero for only a few nuclei, its role toward compactness of hot fusion reactions is found to be as important as that of ${\ensuremath{\beta}}_{4}$. With ${\ensuremath{\beta}}_{3}$ included, depending on its sign and magnitude, the belly-to-belly compact, bbc (or equatorial compact, ec), configuration due to ${\ensuremath{\beta}}_{4}$ changes to not-belly-to-belly compact, nbbc (or not-equatorial compact, nec), and vice versa. Similarly, ${\ensuremath{\beta}}_{6}$ is found to be as important as ${\ensuremath{\beta}}_{3}$ and/or ${\ensuremath{\beta}}_{4}$ for spherical-plus-deformed nuclei, but is rather insignificant for collisions involving deformed-plus-deformed nuclei. On the other hand, the addition of ${\ensuremath{\beta}}_{8}$ is shown to be insignificant also for spherical-plus-deformed nuclei.