Electromagnetic transitions as a probe for Superdeformation in 28Si

There is great interest in superdeformation in light nuclei, A < 40 region, in particular
alpha-conjugate nuclei in the sd-shell. Enhanced collectivity for such light systems opens
new opportunities to test nuclear-structure theories. Antisymmetrized molecular dynamics,
large-scale shell model and beyond mean-field calculations which predict superdeformed
structures in these regions can be validated and tuned with the aid of experimental evidence
of superdeformed bands in light nuclei. A J(pi) = 6+ state at 12.865 MeV in 28Si
with a measured B(E2) value of more than 25 W.u for the transition to the 10.946-MeV
J(pi) = 4+ state is indicative of a highly collective transition and has been thought to form
part of a candidate SD band. Measurements of in-band electromagnetic transitions are
required to fully describe this proposed SD band. The CAGRA campaign is a combination
of small-angle inelastic scattering with high resolution
gamma-ray spectroscopy. This method
preferentially populates low-spin and isoscalar natural parity states. A 12 Clover + 4
LaBr3 array was used in coincidence with the high resolution Grand Raiden spectrometer
to momentum analyse inelastically scattered alpha-particles. The experiment was performed at
the Research Center for Nuclear Physics (RNCP) of Osaka University, Japan. This thesis
will focus on the experimental challenges, analysis and results of the 28Si(alpha,alpha') reaction
at 9.1 degrees with E_beam = 130 MeV impinged on a natural Si target. The first upper limits of the
in-band gamma-ray transition strength of 6.08 W.u from the J(pi) = 4+ to J(pi) = 2+ of the proposed
superdeformed band in 28Si has been measured. This has the potential to constrain future
theoretical predictions of superdeformation in 28Si.