Abstract
Background: Several inclusive and few exclusive [evaporation residue (ER) gated] measurements for symmetric systems reported in the literature describe the anomalous deviations of light particle evaporation spectra from the statistical model predictions. However, no consistent description exists for these deviations.
Purpose: To establish the consistent interpretation of reported anomalous deviations.
Method: The inclusive and exclusive measurements of -particle, proton, and neutron spectra were carried out for the fusion of two relatively symmetric systems Si + Sc (E = 125 MeV and l = 47) and S + Sc (E = 125 MeV and l = 43) leading to the compound nuclei Br and Rb with excitation energies 78 MeV and 71 MeV, respectively.
Results: The experimental light particle spectra for both the reactions show anomalous deviations from the statistical model predictions. The charged particles spectra are found to be suppressed, whereas the neutron spectra exhibit a bump at the higher energy tail. These spectra are investigated in terms of the modification of the important ingredients of the statistical model viz. the level density parameter, rescaling of the yrast line, and the use of value suggested by the dynamical models.
Conclusions: It is conjectured that the higher partial waves do not fuse, but result in the formation of a deformed dinuclear system. The binding energy of neutrons is reduced while those for protons and particles are enhanced in the deformed dinuclear system as compared to those in the shape-equilibrated system. Hence, the higher partial waves inhibit their contributions to the -particle spectra and lead to the preshape equilibrium of neutrons and protons, with the neutron emission dominating over the proton emission.
4 More- Received 9 August 2013
- Revised 12 February 2014
DOI:https://doi.org/10.1103/PhysRevC.89.034621
©2014 American Physical Society