Extreme nuclear shapes examined via giant dipole resonance lineshapes in hot light-mass systems

Abstract

The influence of alpha clustering on nuclear reaction dynamics is investigated using the giant dipole resonance (GDR) lineshape studies in the reactions (20)Ne (E(lab) = 145, 160 MeV) + (12)C and (20)Ne (E(lab) = 160 MeV) + (27)Al, populating (32)S and (47)V, respectively. The GDR lineshapes from the two systems are remarkably different from each other. Whereas, the non-alpha-like (47)V undergoes Jacobi shape transition and matches exceptionally well with the theoretical GDR lineshape estimated under the framework rotating liquid drop model (RLDM) and thermal shape fluctuation model (TSFM) signifying shape equilibration, for the alpha cluster (32)S an extended prolate kind of shape is observed. This unusual deformation, seen directly via gamma decay for the first time, is predicted to be due to the formation of orbiting dinuclear configuration or molecular structure of (16)O+ (16)O in the (32)S superdeformed band.