Excitation of nuclear anharmonic vibrations in heavy-ion fusion reactions

Abstract

We discuss the effects of multi-phonon excitations on heavy-ion fusion reactions at energies near and below the Coulomb barrier, focusing especially on the role of anharmonicities. We carry out a systematic study of those effects on the excitation function of the fusion cross section and on the fusion barrier distribution, by using the vibrational limit of the interacting boson model. We also analyze the recently measured high-precision data of the 16 O + 148 Sm fusion reaction with this model and discuss the anharmonic properties of the quadrupole as well as the octupole vibrations in 148 Sm. Negative and positive static quadrupole moments are deduced for the first 2 + and 3 − states in 148 Sm, respectively. It is shown that the fusion barrier distribution strongly depends on the sign of the quadrupole moments, suggesting that subbarrier fusion reactions offer an alternative method to extract the static quadrupole moments of phonon states in spherical nuclei.PACS number(s): 25.70. Jj, 21.60.Fw, 21.10.Ky, 27.60.+j

Anharmonicity of multi–octupole-phonon excitations inPb208: Analysis with multireference covariant density functional theory and subbarrier fusion ofO16Yao1, Hagino2 2016Phys. Rev. CSelf Cite182110View full textAdd to dashboardCite

“…Incidentally, heavy-ion fusion reactions provide an alternative way to probe the multi-phonon excitations in atomic nuclei, which significantly affect the subbarrier fusion cross sections [16][17][18][19] as illustrated by coupled-channels calculations [16,20,21]. Previous coupled-channels calculations for the fusion reaction of 16 O+ 208 Pb based on multi-harmonic-phonon excitations fail to reproduce the observed energy dependence of fusion cross sections [22][23][24], and overestimate the height of the main peak in the so called fusion barrier distribution [25].…”

“…Incidentally, heavy-ion fusion reactions provide an alternative way to probe the multi-phonon excitations in atomic nuclei, which significantly affect the subbarrier fusion cross sections [16][17][18][19] as illustrated by coupled-channels calculations [16,20,21]. Previous coupled-channels calculations for the fusion reaction of 16 …”

Semimicroscopic modeling of heavy-ion fusion reactions with multireference covariant density functional theory

“…Therefore, the conclusion in Refs. [12,13] remains the same, that is, the sign of the quadrupole moment of an excited state can be determined with heavyion subbarrier fusion reactions, when high precision experimental data are available. For the 58 Ni+ 58 Ni system shown in Fig.…”

“…In Refs. [12,13], the effect of anharmonicity on subbarrier fusion of 16 O+ 144,148 Sm has been investigated using the vibrational limit of interacting boson model (IBM). See also Ref.…”

“…[14] for an application of this method to large-angle quasi-elastic scattering of the 16 O+ 144 Sm system. Although the static quadrupole moment of the first excited state could be successfully extracted by analyzing the high precision experimental data with this approach [12,13], the application of IBM has several limitations for a global study. Firstly, the method is not applicable to doubly magic nuclei, as the number of bosons in IBM is estimated from the number of valence nucleons outside shell closures.…”