A study of resonant structures in the neon-20 + oxygen-16 system

Yuanjun Miao, University of Pennsylvania


In a search for high spin molecular states in $\sp{36}$Ar, the $\sp{20}$Ne + $\sp{16}$O system was studied using a differentially pumped windowless $\sp{20}$Ne gas target. The exit channel mass partitions $\sp{20}$Ne + $\sp{16}$O, $\sp{24}$Mg + $\sp{12}$C, $\sp{16}$O + $\sp{16}$O + $\alpha$, and $\sp{18}$F + $\sp{18}$F have been identified in the current work. Angle-averaged excitation functions were obtained for the energy range 16.39 MeV $\le E\sb{cm} \le$ 41.67 MeV in 278 keV steps. Inelastic scattering involving the $\sp{16}$O(0$\sbsp{2}{+}$, 6.05 MeV) state was separated from the nearby $\sp{16}$O(3$\sbsp{1}{-}$, 6.13 MeV) state by detecting the $e\sp{-}$ and $e\sp{+}$ emitted from the internal pair decay of the $\sp{16}$O(0$\sbsp{2}{+}$) state. A statistical fluctuation analysis for the $\sp{20}$Ne + $\sp{16}$O and $\sp{24}$Mg + $\sp{12}$C mass partitions indicates that a few weakly correlated structures are present in the current system. Tentative spin assignments based on angular distribution measurements suggest that the resonant structures are possibly associated with rotational states of $\sp{36}$Ar, which are about 10 MeV higher than results from a cranked cluster model calculation$\sp1$. The large branching ratios to the low-lying inelastic channels from these resonances may suggest the $\sp{16}$O-$\alpha$-$\sp{16}$O configuration in the compound system. The structures observed in the current data are considered to be different in decay behavior from the molecular states seen in $\sp{48}$Cr populated by the $\sp{24}$Mg + $\sp{24}$Mg entrance channel$\sp2$. Unexpectedly large cross sections, comparable to those in the inelastic scattering channels, are reported for the $\sp{18}$F + $\sp{18}$F exit channel at a Q value corresponding to a total excitation energy of 2 MeV. ftn$\sp1$W. D. Rae, et al., Phys. Lett. 279B, 207(1992). $\sp2$R. W. Zurmuhle, et al., Phys. Lett. 129B, 384(1983).

Subject Area

Nuclear physics

Recommended Citation

Miao, Yuanjun, "A study of resonant structures in the neon-20 + oxygen-16 system" (1995). Dissertations available from ProQuest. AAI9532246.