Deformation in28Si*produced via the16O+

S. Kundu

¹

,

C. Bhattacharya

²

,

Subhashish Bhattacharya

³

et al.

Abstract

The energy spectra of the α particles emitted in the reactions 16 O (7-10 MeV/nucleon) + 12 C have been measured in the center-of-mass angular range of 25 • θ c.m. 70 • . The experimental energy spectra have been compared with those obtained from the statistical model calculation with "deformability" parameters predicted by rotating liquid drop model (RLDM) and also fitted the same with optimized deformability parameters, which are quite different from the respective RLDM values. The data have also been found to be explained quite well using "frozen" deformation approximation, where the deformability parameters have been kept fixed at RLDM values of the parent nucleus throughout the decay process. The effective radius in the latter case is smaller compared to that obtained using the optimized parameters; however, in both cases, the deformations (effective radii) are larger than the corresponding RLDM values. So, considering the uncertainties in the estimation of actual compound nucleus deformations, it can, only qualitatively, be said that equilibrium orbiting, which is similar to particle evaporation in time scale, could also be one of the contributing factors for the observed deformation.

Study of the Jacobi shape transition in A≈30 nuclei

“…It should be mentioned that the earlier data reporting the signature of orbiting in Ref. [36] from the charged particle spectra, have shown the co-existence of molecular resonance states with equilibrated compound nucleus formation. In such a scenario, it is possible that high J components of the entrance channel are predominantly contributing to the orbiting state and consequently the CN is formed with J < J C .…”

“…The effect of direct reactions like pre-equilibrium emission, incomplete fusion etc. is not considered, since it has been shown to be negligible for 16 O+ 12 C at the present beam energy [36]. Most noteworthy is the striking difference between the GDR spectra in two reactions leading to 31 P and 28 Si nuclei.…”

Anomalous deviations from statistical evaporation spectra for the decay of the73Br and77Rb compound systems

“…The higher energy tail of the charged particles spectra are softer while for the neutrons the spectra are harder in comparison to the statistical model predictions and exhibit a bump which is a critical signature for pre-equilibrium process [13]. The deviation of α-particle spectra has been explained using different methods like the modification of spin dependent level density or optimizing the deformation parameters [14][15][16][17]. However, these methods failed to explain the proton spectra for some target-projectile combinations [2,3,16].…”