3,667 research outputs found
Emergence of nuclear clustering in electric-dipole excitations of Li
Nuclear clustering plays an important role, especially in the dynamics of
light nuclei. The importance of the emergence of the nuclear clustering was
discussed in the recent measurement of the photoabsorption cross sections as it
offered the possibility of the coexistence of various excitation modes which
are closely related to the nuclear clustering. To understand the excitation
mechanism, we study the electric-dipole () responses of Li with a fully
microscopic six-body calculation. The ground-state wave function is accurately
described with a superposition of correlated Gaussian (CG) functions with the
aid of the stochastic variational method. The final-state wave functions are
also expressed by a number of the CG functions including important
configurations to describe the six-body continuum states excited by the
field. We found that the out-of-phase transitions occur due to the oscillations
of the valence nucleons against the He cluster at the low energies around
10 MeV indicating ``soft'' giant-dipole-resonance(GDR)-type excitations, which
are very unique in the Li system but could be found in other nuclear
systems. At the high energies beyond MeV typical GDR-type transitions
occur. The He-H clustering plays an important role to the GDR phenomena
in the intermediate energy regions around 20 MeV.Comment: 13 pages, 10 figure
Evidence for <i>L</i>-dependence generated by channel coupling: <sup>16</sup>O scattering from <sup>12</sup>C at 115.9 MeV
Background: In earlier work, inversion of S matrix for 330 MeV 16O on 12C resulted in highly undulatory potentials; the S matrix resulted from the inclusion of strong coupling to states of projectile and target nuclei. L-independent S-matrix equivalent potentials for other explicitly L-dependent potentials have been found to be undulatory.
Purpose: To investigate the possible implications of the undulatory dynamic polarization potential for an underlying L dependence of the 16O on 12C optical potential.
Methods: S matrix to potential, SL
→ V (r), inversion which yields local potentials that reproduce the elastic channel S matrix of coupled channel (CC) calculations, will be applied to the S matrix for 115.9 MeV 16O on 12C. Further, SL for explicitly L-dependent potentials are inverted and the resulting L-independent potentials are characterized and compared with the undulatory potentials found for 16O on 12C.
Results: Some of the undulatory features exhibited by the potentials modified by channel coupling for 115.9 MeV 16O on 12C can be simulated by simple parameterized L-dependent potentials.
Conclusions: The elastic scattering of 16O by 12C is a particularly favorable case for revealing the effective L dependence of the potential modified by channel coupling. Nevertheless, there is no reason to suppose that
undularity is not a generic property leading in many cases to the choice: nucleus-nucleus potentials are (i) smooth and L-dependent, (ii) L-independent and undulatory, or (iii) both
Neutrino Induced 4He Break-up Reaction -- Application of the Maximum Entropy Method in Calculating Nuclear Strength Function
The maximum entropy method is examined as a new tool for solving the
ill-posed inversion problem involved in the Lorentz integral transformation
(LIT) method. As an example, we apply the method to the spin-dipole strength
function of 4He. We show that the method can be successfully used for inversion
of LIT, provided the LIT function is available with a sufficient accuracy.Comment: 5 pages, 2 figures. Poster presented by TM at the International
Workshop on Neutrino-Nucleus Interaction in the Few-GeV Region (NuInt15),
Novenber 16-21 2015, Osaka, Japa
- …