Study of Jacobi shape transition in α cluster and non-α cluster nuclei.

The nuclear shape change as a function of angular momentum and temperature is one of the interesting topics in nuclear structure physics. Of particular interest is the Jacobi shape transition, an abrupt change of nuclear shape from non-collectively rotating oblate to collectively rotating triaxial/prolate, probed via giant dipole resonance built on excited states. The clustering structure of the nuclei also plays an important role in reaction dynamics. Therefore, in order to understand the role played by α clustering, the Jacobi shape transition of α cluster and non-α cluster nuclei has been investigated. This talk will present preliminary results of the experiments carried out at PLF, in reaction of 16O+12C@Elab=125 MeV and 19F+12C@Elab=127 MeV populating 28Si (α cluster) and 31P (non-α cluster), respectively. The preliminary results indicate an enhancement around ∼10 MeV in the high energy γ-ray spectrum in 31P non-α cluster nuclei, which could be the signeture of Jacobi shape transition. In addition to this, a PARIS (Photon Array for the Studies with Radioactive Ion and Stable beams) mini-cluster has been set-up and was tested in-beam with digital readout electronics. Some of these results together with the studies of neutron interaction in PARIS phoswich detector will be presented.