Effects of mass renormalization on the surface properties of heavy-ion fusion potential

We discuss the effects of fast nuclear excitations on heavy-ion fusion reactions at energies near and below the Coulomb barrier. Using the fusion of two $^{40}$Ca nuclei as an example and the inversion method, we show that the mass renormalization induced by fast nuclear excitations leads to a large surface diffuseness in the effective potential for heavy-ion fusion reactions.Comment: 13 pages, Late

Anharmonic phonon excitations in subbarrier fusion reactions

Recently measured high precision data of fusion excitation function have enabled a detailed study on the effects of nuclear collective excitations on fusion reactions. Using such highly accurate data of the $^{16}$O + $^{144,148}$Sm reactions, we discuss the anharmonic properties of collective phonon excitations in $^{144,148}$Sm nuclei. It is shown that subbarrier fusion reactions are strongly affected by the anharmonic effects and thus offer an alternative method to extract the static quadrupole moments of phonon states in a spherical nucleus.Comment: 10 pages, To be published in the Proceedings of the Tours Symposium on Nuclear Physics III, Tours, France, September 1997 (American Institute of Physics

Spatially Resolved NMR Relaxation Rate in a Noncentrosymmetric Superconductor

We numerically study the spatially-resolved NMR around a single vortex in a noncentrosymmetric superconductor such as CePt3Si. The nuclear spin-lattice relaxation rate 1/T1 under the influence of the vortex core states is calculated for an s+p-wave Cooper pairing state. The result is compared with that for an s-wave pairing state.Comment: 2 pages; submitted to Proc. of SCES'0

Evidence of Double Phonon Excitations in ^{16}O + ^{208}Pb Reaction

The fusion cross-sections for ^{16}O + ^{208}Pb, measured to high precision, enable the extraction of the distribution of fusion barriers. This shows a structure markedly different from the single-barrier which might be expected for fusion of two doubly-closed shell nuclei. The results of exact coupled channel calculations performed to understand the observations are presented. These calculations indicate that coupling to a double octupole phonon excited state in ^{208}Pb is necessary to explain the experimental barrier distributions.Comment: 6 pages, 2 figures, To be published in the Proceedings of the FUSION 97 Conference, South Durras, Australia, March 1997 (J. Phys. G

Radiation correction to astrophysical fusion reactions and the electron screening problem

We discuss the effect of electromagnetic environment on laboratory measurements of the nuclear fusion reactions of astrophysical interest. The radiation field is eliminated using the path integral formalism in order to obtain the influence functional, which we evaluate in the semi-classical approximation. We show that enhancement of the tunneling probability due to the radiation correction is extremely small and does not resolve the longstanding problem that the observed electron screening effect is significantly larger than theoretical predictions.Comment: 9 pages, 1 eps figure

Fusion barrier distributions in systems with finite excitation energy

Eigen-channel approach to heavy-ion fusion reactions is exact only when the excitation energy of the intrinsic motion is zero. In order to take into account effects of finite excitation energy, we introduce an energy dependence to weight factors in the eigen-channel approximation. Using two channel problem, we show that the weight factors are slowly changing functions of incident energy. This suggests that the concept of the fusion barrier distribution still holds to a good approximation even when the excitation energy of the intrinsic motion is finite. A transition to the adiabatic tunneling, where the coupling leads to a static potential renormalization, is also discussed.Comment: 9 pages, 4 figures, Submitted to Physical Review