Vanishing spin alignment : experimental indication of triaxial ${}^{28}\mathbf{Si}+{}^{28}\mathbf{Si}$ nuclear molecule

Abstract

Fragment-fragment-${\hat{I}}^3$ coincidences have been measured for ${}^{28}\mathrm{Si}+{}^{28}\mathrm{Si}$ at an energy corresponding to the population of a conjectured resonance in ${}^{56}$Ni. Fragment angular distributions as well as ${\hat{I}}^3$-ray angular correlations indicate that the spin orientations of the outgoing fragments are perpendicular to the orbital angular momentum. This differs from the ${}^{24}\mathrm{Mg}+{}^{24}\mathrm{Mg}$ and the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ resonances, and suggests two oblate ${}^{28}\mathrm{Si}$ nuclei interacting in an equator-to-equator molecular configuration.

14 pages standard REVTeX file, 3 ps Figures -- Accepted for publication in Physical Review C (Rapid Communication)