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Spectroscopy of high spin states in O 16 and Ne </mml:…

1979; American Institute of Physics; Volume: 20; Issue: 5 Linguagem: Inglês

10.1103/physrevc.20.1743

1538-4497

S. Sanders, L. M. Martz, P. D. Parker,

Atomic and Molecular Physics

Spins, parities, and ${\ensuremath{\alpha}}_{0}$-decay branching ratios have been determined for a number of states in $^{16}\mathrm{O}$ and $^{20}\mathrm{Ne}$ using the $^{12}\mathrm{C}$($^{12}\mathrm{C}$, $^{8}\mathrm{Be}$)$^{16}\mathrm{O}$*(${\ensuremath{\alpha}}_{0}$)$^{12}\mathrm{C}$ and $^{16}\mathrm{O}$($^{12}\mathrm{C}$, $^{8}\mathrm{Be}$)$^{20}\mathrm{Ne}$*(${\ensuremath{\alpha}}_{0}$)$^{16}\mathrm{O}$ reactions. The $^{8}\mathrm{Be}$ nuclei were detected at 0\ifmmode^\circ\else\textdegree\fi{}, and the alpha particles from the decay of the excited states formed in the ($^{12}\mathrm{C}$, $^{8}\mathrm{Be}$) reactions were detected over the range $40\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{lab}}\ensuremath{\le}97\ifmmode^\circ\else\textdegree\fi{}$, typically corresponding to a range in the heavy-recoil center-of-mass system of $50\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{RCM}}\ensuremath{\le}120\ifmmode^\circ\else\textdegree\fi{}$. Structure observed at an excitation energy of 22.5\ifmmode\pm\else\textpm\fi{}0.5 MeV in $^{16}\mathrm{O}$ appears to correspond to an ${8}^{+}$ state which is then a candidate for identification as the ${8}^{+}$ member of the ${K}^{\ensuremath{\pi}}={0}^{+}, 4\mathrm{p}\ensuremath{-}4\mathrm{h}$ rotational band. In $^{20}\mathrm{Ne}$ we have confirmed a number of spin assignments for states below 16 MeV in excitation, and in addition we have made the following assignments: 16.63 MeV (${7}^{\ensuremath{-}}$), 17.3 MeV (${8}^{+}$), 21.08 MeV (${9}^{\ensuremath{-}}$), and 22.87 MeV (${9}^{\ensuremath{-}}$). All of the ${\ensuremath{\alpha}}_{0}$ branching ratios for the strongly populated states in $^{20}\mathrm{Ne}$ are found to be roughly 100%, with the exception of those for the 17.3 MeV (${8}^{+}$) and 21.08 MeV (${9}^{\ensuremath{-}}$) levels which are found to be 40% and 65%, respectively.NUCLEAR REACTIONS $^{12}\mathrm{C}$($^{12}\mathrm{C}$, $^{8}\mathrm{Be}$)$^{16}\mathrm{O}$*(${\ensuremath{\alpha}}_{0}$)$^{12}\mathrm{C}$, $^{16}\mathrm{O}$($^{12}\mathrm{C}$, $^{8}\mathrm{Be}$) $^{20}\mathrm{Ne}$*(${\ensuremath{\alpha}}_{0}$)$^{16}\mathrm{O}$, particle-particle angular correlations; ${E}_{\mathrm{lab}}=78$ MeV, ${\ensuremath{\theta}}_{^{8}\mathrm{Be}}\ensuremath{\approx}0\ifmmode^\circ\else\textdegree\fi{}$. Deduce ${J}^{\ensuremath{\pi}}$, $\frac{{\ensuremath{\Gamma}}_{{\ensuremath{\alpha}}_{0}}}{{\ensuremath{\Gamma}}_{\mathrm{total}}}$.