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

Theoretical study of the electronic states of hollandite vanadate K 2V8O16

Electronic states of hollandite vanadate K2V8O 16, a one-dimensional zigzag-chain system of t2g orbitals in a mixed valent state, are considered. We calculate the Madelung energies to determine the most stable charge-ordering pattern that is consistent with the observed superlattice structure. We then develop the strong-coupling perturbation theory to derive the effective spin-orbit Hamiltonian, starting from the triply-degenerate t2g orbitals in the VO6 octahedral structure. An exact-diagonalization technique is used on small clusters of this Hamiltonian to determine the orbital-ordering pattern and spin structures in the ground state. We thereby discuss the electronic and magnetic properties of K2 V8O16. © 2009 IOP Publishing Ltd.Ministry of Education, Culture, Sports, Science and Technology of Japan/18028008Ministry of Education, Culture, Sports, Science and Technology of Japan/18043006Ministry of Education, Culture, Sports, Science and Technology of Japan/185400338Ministry of Education, Culture, Sports, Science and Technology of Japan/19014004JSPS Research Fellowship for Young Scientist

A Comparative Study of the Parker Instability under Three Models of the Galactic Gravity

To examine how non-uniform nature of the Galactic gravity might affect length and time scales of the Parker instability, we took three models of gravity, uniform, linear and realistic ones. To make comparisons of the three gravity models on a common basis, we first fixed the ratio of magnetic pressure to gas pressure at $\alpha$ = 0.25, that of cosmic-ray pressure at $\beta$ = 0.4, and the rms velocity of interstellar clouds at $a_s$ = 6.4 km s$^{-1}$, and then adjusted parameters of the gravity models in such a way that the resulting density scale heights for the three models may all have the same value of 160 pc. Performing linear stability analyses onto equilibrium states under the three models with the typical ISM conditions, we calculate the maximum growth rate and corresponding length scale for each of the gravity models. Under the uniform gravity the Parker instability has the growth time of 1.2$\times10^{8}$ years and the length scale of 1.6 kpc for symmetric mode. Under the realistic gravity it grows in 1.8$\times10^{7}$ years for both symmetric and antisymmetric modes, and develops density condensations at intervals of 400 pc for the symmetric mode and 200 pc for the antisymmetric one. A simple change of the gravity model has thus reduced the growth time by almost an order of magnitude and its length scale by factors of four to eight. These results suggest that an onset of the Parker instability in the ISM may not necessarily be confined to the regions of high $\alpha$ and $\beta$.Comment: Accepted for publication in ApJ, using aaspp4.sty, 18 text pages with 9 figure

Global density-dependent α\alpha-nucleon interaction for α\alpha-nucleus elastic scattering

We provide a global density-dependent $^4$He-nucleon (DD-$\alpha N$) interaction to construct the $\alpha$-nucleus optical model potential (OMP) in a wide range of incident energies. The global parametrization for the DD-$\alpha N$ interaction is obtained based on the proton-$^4$He OMP which reproduces the elastic scattering cross-section data very well in the incident energies of 12.04--500 MeV per nucleon. We derive the $\alpha$-nucleus potential by a folding procedure with the point-nucleon density obtained by a microscopic mean-field model using the present DD-$\alpha N$ interaction. The density dependence of the DD-$\alpha N$ interaction is fixed phenomenologically to reproduce the $\alpha$-nucleus elastic scattering cross-section data by the $^{16}$O, $^{40}$Ca, $^{58}$Ni, $^{90}$Zr, and $^{208}$Pb targets at $E/A =$ 10--342.5 MeV. We also show the total reaction cross sections, which are helpful in fixing one free parameter, the renormalization factor for the imaginary part of the $\alpha$-nucleus potential. Lastly, we show some examples, which clearly demonstrate the validity and power of the present DD-$\alpha N$ approach.Comment: 20 pages, 11 figure

Enlarged deformation region in neutron-rich Zr isotopes by the second intruder orbit

Nuclear deformations and density profiles of neutron-rich even-even Zr isotopes are investigated using the Skyrme-Hartree-Fock-Bogoliubov method. Large quadrupole and hexadecapole deformations are predicted along with large enhancement of the total reaction cross sections at the neutron number $N=60$-74. Strong nuclear deformation starting at $N=60$ is induced by the occupation of the intruder orbit with the asymptotic quantum number $[nn_z\Lambda]\Omega$ = [550]1/2 originating from the spherical $0h_{11/2}$ orbit. The deformation region is further enlarged from $N=72$ to 74 owing to the occupation of the next intruder orbit with [530]1/2 originating from the spherical $1f_{7/2}$ orbit. This characteristic nuclear deformation is crucially reflected in the systematic behavior of the nuclear radii and the density profiles near the nuclear surface.Comment: 7 pages, 6 figures, to appear in Phys. Rev. C (Letter