# A study of correlated structure in three systems: Silicon-28, magnesium-24, and neon-20 + neon-20

#### Abstract

A differentially pumped windowless $\sp{20}$Ne gas target was used to investigate three systems: $\rm\sp{28}Si$ + $\rm\sp{20}Ne,\ \sp{24}Mg$ + $\rm\sp{20}Ne,$ and $\rm\sp{20}Ne$ + $\rm\sp{20}Ne.$ The system $\rm\sp{28}$Si + $\sp{20}$Ne is studied over a region of excitation energy in $\sp{48}$Cr from 50.5 to 67.5 MeV, measurements in the system $\sp{24}$Mg + $\sp{20}$Ne extended over a region of excitation energy in $\sp{44}$Ti from 51.0 to 71.0 MeV, and the system $\sp{20}$Ne + $\sp{20}$Ne covered a region of excitation energy in $\sp{40}$Ca from 51.5 to 58.5 MeV. Previous work on the $\sp{24}$Mg + $\sp{24}$Mg system$\sp{1,2}$ suggested that the reactions $\rm\sp{24}Mg(\sp{24}Mg,\sp{24}Mg\sp\*)\sp{24}Mg\sp\*$ and $\rm\sp{24}Mg(\sp{24}Mg,\sp{20}Ne\sp\*)\sp{28}Si\sp\*$ are dominated by the population of high spin molecular configurations in $\sp{48}$Cr that strongly resemble two $\sp{24}$Mg nuclei aligned pole-to-pole. The shape of the ground state of $\sp{24}$Mg and the calculated shapes of the high spin states in $\sp{48}$Cr suggested the $\sp{24}$Mg + $\sp{20}$Ne and $\sp{20}$Ne + $\sp{20}$Ne systems would be dominated by similar resonance structures. A statistical fluctuation analysis for the $\sp{28}$Si + $\sp{20}$Ne and $\sp{24}$Mg + $\sp{20}$Ne systems, combined with angular distribution measurements for each system, indicate that the systems included in this thesis are not dominated by similar phenomena. The differences between $\sp{28}$Si + $\sp{20}$Ne and $\sp{24}$Mg + $\sp{24}$Mg are consistent with the differences in the barrier heights of these two systems. A review of the previously assumed systematics for the observation of correlated high spin resonance phenomena suggests that the absence of similar high spin structure in the other two systems is due to shell model corrections that reduce the deformation of the yrast bands in $\sp{40}$Ca and $\sp{44}$Ti relative to the yrast band in $\sp{48}$Cr, which reduces the shape matching with the respective entrance channels, relative to the $\sp{24}$Mg + $\sp{24}$Mg $\to\ \sp{48}$Cr$\sp\*$ system. ftn$\sp1$R. W. Zurmuhle, et al. Phys. Lett. 129B, 384 (1983). $\sp2$S. Saini et al. Phys. Lett. 185B, 316, (1987).

Nuclear physics

#### Recommended Citation

Barrow, Stephen Paxton, "A study of correlated structure in three systems: Silicon-28, magnesium-24, and neon-20 + neon-20" (1994). Dissertations available from ProQuest. AAI9427499.
https://repository.upenn.edu/dissertations/AAI9427499

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