-
Article type: Cover
1991 Volume 83 Issue 4 Pages
Cover1-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Article type: Appendix
1991 Volume 83 Issue 4 Pages
App1-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Article type: Appendix
1991 Volume 83 Issue 4 Pages
D1-D8
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
W. CASSING, B. BLATTEL, V. KOCH, U. MOSEL
Article type: Article
1991 Volume 83 Issue 4 Pages
D9-D18
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
The description of heavy-ion collisions up to bombarding energies of a few GeV per nucleon is based on a relativistic transport equation for the baryon phase-space distribution as derived from time-dependent Dirac-Brueckner theory within semi classical limits. It describes the selfconsistent mean-field dynamics with its momentum-dependent forces as well as the residual nucleon-nucleon collisional history. We analyze the sensitivity of collective flow observables to the scalar and vector part of the nucleon selfenergy and its relation to the nuclear equation of state.
View full abstract
-
A. Ohnishi, T. Maruyama, H. Horiuchi
Article type: Article
1991 Volume 83 Issue 4 Pages
D19-D25
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
Deep-inelastic collision is studied by the use of Quantum Molecular Dynamics. The ridge line and the width at large angles of WIlczynski plot in the reaction ^<16>O+^<93>Nb(204MeV) are well described by QMD. The width at large angles are largely due to the stochasticity of 2-nucleon collisions. The contribution of collective motions of fragments-rotations and vibrations-to the energy loss is also studied, and calculated to be about 20 〜 30 MeV in this reactoin.
View full abstract
-
Toshiki Maruyama, Akira Ohnishi, Hisashi Horiuchi
Article type: Article
1991 Volume 83 Issue 4 Pages
D26-D31
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
We applied QMD method to investigate the evolution of the reaction mechanisms in ^<16>O+^<16>O system for the energy region from about 1 MeV/u to several hundreds MeV/u. The fragment mass distribution shows us the outline of incident energy and impact parameter dependence of reaction mechanisms. For the low energy region, fusion reaction is dominant and there is little impact parameter dependence. The calculated complete fusion reaction cross section reproduced the experiments well. For the energy region of E_<lab> ≳ 30 or 50 MeV/u, there appear distinct impact parameter dependence; for head on reaction the reaction evolves to explosion, and for b=3 fm P-S-like processes appear, and for b=5 fm the reaction evolves to DIC-like and to QE process. For the P-S-like processes and DIC-like processes, we will discuss elsewhere.
View full abstract
-
K. Yabana
Article type: Article
1991 Volume 83 Issue 4 Pages
D32-D37
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
P. Frobrich
Article type: Article
1991 Volume 83 Issue 4 Pages
D38-D45
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Taksu Cheon
Article type: Article
1991 Volume 83 Issue 4 Pages
D46-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
T. Mizusaki
Article type: Article
1991 Volume 83 Issue 4 Pages
D47-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Kazuhiro MURAMATSU
Article type: Article
1991 Volume 83 Issue 4 Pages
D48-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Michael Berry
Article type: Article
1991 Volume 83 Issue 4 Pages
D49-D50
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
T. Yukawa
Article type: Article
1991 Volume 83 Issue 4 Pages
D51-D59
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Hiroshi Hasegawa
Article type: Article
1991 Volume 83 Issue 4 Pages
D60-D73
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
We discuss Yukawa's scope [1] on Dynamical theory of level statistics (see §2 of article [1a] by Yukawa and Ishikawa in 1989). A brief outline of this chapter will extract,three basic questions to be answered: (a) What is the Ilamiltonian structure of the level dynamics (Poisson -bracket re- lations and the Liouville theorem)? (b) Is the proposed joint distribution, intermediate between Poissonian and Gaussian, legetimate? (c) How this distribution can be used to describe the actual level statistics, in particular, that for near integrable systems? Our answers are affirmative and concrete to an extent, as can be seen in this report.
View full abstract
-
Hans A. Weidenmuller
Article type: Article
1991 Volume 83 Issue 4 Pages
D74-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
N. Takigawa
Article type: Article
1991 Volume 83 Issue 4 Pages
D75-D85
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
I discuss two subjects concerning the decay of a metastable state in a system with many degrees of freedom. In the first part, I discuss the effect of a surface vibration of the residual nucleus on the energy spectrum of particles emitted from a hot compound nucleus. In the second part, I derive a formula of the fission width based on a path integral evaluation of the imaginary part of the free energy, and discuss how the Kramers formula is modified by the memory effect for viscosity and by the quantum fluctuation of the fission path. Attention is particularly paid to the effects of the finite range property of the coupling Hamiltonian between the fission coordinate and the environmantal degrees of freedom, which are represented by a set of harmonic oscillators. Also, I sketch the present understanding of the large enhancement of the heavy ion fusion cross section at sub-barrier energies.
View full abstract
-
S. Yamaji, H. Hofmann, A. S. Jensen
Article type: Article
1991 Volume 83 Issue 4 Pages
D86-D88
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Y. Alhassid
Article type: Article
1991 Volume 83 Issue 4 Pages
D89-D100
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
The fluctuation properties of the spectrum and of the electromagnetic B(E2) transition of low-lying collective states of nuclei are studied. Using the framework of the interacting boson model we discuss the transition between rotational and γ-unstable nuclei. Near those two limits the system exhibits regular behavior but in the transition region it shows chaotic behavior, where the fluctuations of both the levels and the E2 intensities approach those characterizing the Gaussian Orthogonal Ensemble of random matrices. Analysis of the classical mean-field dynamics of the five nuclear quadrupole shape degrees of freedom confirms the quantal results.
View full abstract
-
Y. HASHIMOTO
Article type: Article
1991 Volume 83 Issue 4 Pages
D101-D112
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Hidehiko TSUKUMA
Article type: Article
1991 Volume 83 Issue 4 Pages
D113-D118
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
Quantum chaoticity is studied from a viewpoint of nuclear collective dynamics. A definition of quantum chaoticity is presented by means of the microscopic theory of large amplitude collective dynamics based on the quantum vergion of the self-consistent collective coordinate method. Furthermore, the distribution function F_i(q_1, q_2) is calculated for a typical regular state and a typical chaotic one determined by our theory, and physical meaning of our definition of quantum chaoticity is discussed from a viewpoint of classical picture.
View full abstract
-
Yoshifumi R. Shimizu, Thomas Dossing, Enrico Vigezzi, Ricardo A. Brogl ...
Article type: Article
1991 Volume 83 Issue 4 Pages
D119-D130
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
The mechanism of decays of the superdeformed rotational bands is studied as a barrier penetration problem by making use of microscopically calculated potential energy surfaces in the (ε_2, γ)-plane. The transmission coefficients extracted by a recently proposed model of the decay out of superdeformed bands are compared with the results of calculation which are obtained by the semiclassical method of an "invariant adiabatic path". It is found that the effect of pairing correlations on the potential energy and/or the mass tensor is essential in order to account for the rapid depopulation of superdeformed rotational bands.
View full abstract
-
K. SUGAWARA-TANABE
Article type: Article
1991 Volume 83 Issue 4 Pages
D131-D140
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
The thermal RPA equation based on the thermal cranked HFB ensemble is solved for the thermal giant dipole resonance excited on the high spin superdeformed states in ^<132>Ce.
View full abstract
-
H. Nishioka
Article type: Article
1991 Volume 83 Issue 4 Pages
D141-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Kosai TANABE
Article type: Article
1991 Volume 83 Issue 4 Pages
D142-D143
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
Fully self-consistent microscopic approaches to the nuclear structure in the offyrast region are reviewed with special emphasis lay eel on the basic importance of the thermal Hrtree-Fock-Bogoliubov (THFB) approximation. for the description of average properties of highly excited nucleus, and the thermal RPA (TRPA) on top of the THFB quasiparticle picture in taking account of the thermal effect on the mean field for the description of giant dipole resonances (GDR) built on the hot rotating nucleus. It has been shown that the particle number- and angular momentum-constrained Hartree-Fock-Bogoliubov (CHFB) approximation can provide correct microscopic interpretation of the backbending behaviour of rotational level sequence along yrast in terms of the gapless superconductivity, detailed informations about behaviour of single-particle orbitals in coexisting different shapes, accurate simultaneous reproduction of both backbends and g-factors and reproduction of superdeformed bands for the nuclides in the A = 130 region. Preserving these outstanding merits of the CHFB scheme as a fully self-consistent mean field approximation, one can extend the formalism with statistical recipe to the ther- mal HFB (THFB) approximation which is useful in the description of the off-yrast states of nucleus. Some details of the variational derivation of the THFB equation and related formalism have been presented in Ref. 2). The THFB solution can produce a detailed phase diagram of deformed nucleus showing the super-normal phase transition caused by the com- bined effect of rotation and temperature and the possibility of bidirectional alignment of spins in the small angular momentum region for the case of ^<164>Er. A remaining fundamental problem for the THFB formalism was how to prove the Bloch-Messiali theorem for the finite temperature formalism and how to define the level- dependent order parameters in the THFB frmalism. This problem can be solved by applying the thermo field dynamics (TFD). This must be the final completion of the THFB formalism. The TRPA formalism has been developed to describe the GDR at high temperatures. The basic quasiparticle picture is provided by the THFB solution, on top of which the linear response function for the dipole operator corresponding to the displacement vector from the center of mass for protons to the one for neutrons. Overall trends of the GDR observed in some deformed nuclei are well reproduced from the TRPA calculations. To take account of more thermal correlations, further possibility of extending the TRPA formalism is discussed in Ref. 19). By applying the TFD to the variational derivation of the extended TRPA equation, a minimum point of the grand potential is searched for in the RPA parameter manifold of larger dimensionality corresponding to doubled single-particle operator space.
View full abstract
-
Takaharu Otsuka
Article type: Article
1991 Volume 83 Issue 4 Pages
D144-D153
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
A new framework, called Variational Shell Model, is proposed to describe the structure of light neutron-rich exotic nuclei. An application to ^<11>Be is presented, showing that the anomalous 1/2^+ ground state is reproduced very naturally with Skyrme (S III) interaction, in contrast to Hartree-Fock calculation. A new binding mode, called dynamical orbital fluctuation, is suggested as the mechanism responsible for this anomalous ground state.
View full abstract
-
SEIYA NISHIYAMA, HIDEO FUKUTOME
Article type: Article
1991 Volume 83 Issue 4 Pages
D154-D163
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
We developed a general theory to describe a superconducting Fermion system with large quantum fluctuations. The theory is a direct extension of the resonating Hartree-Fock (HF) theory to the Hartree-Bogoliubov case including pair correlations. We start with an exact coherent state representation of a superconducting Fermion system on a special orthogonal group. A state with large quantum fluctuations is approximated by a superposition of non-orthogonal Hartree-Bogo1iubov (HB) wave functions with different correlation structures. We obtain the variational equations to determine the resonating HB wave functions in a quite parallel manner to the resonating HF theory. In order to show the usefulness of the theory, we apply it to a problem of describing the resonance of multiple shapes coexisting in transitional even nuclei. To avoid an unnecessary complication, we adopt the simplest model consisting of two local energy minima of prolate and oblate shapes founded in a pairing plus quadrupole interaction model with three single particle energy levels.
View full abstract
-
Takahiro Fukui
Article type: Article
1991 Volume 83 Issue 4 Pages
D164-D167
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
A new microscopic method based on the diabatic picture is proposed to describe the low-lying deformed excited 0^+ states in semi-magic nuclei. In this method, the couplings between anharmonic shape vibrations associated with different Hartree-Fock-Bogoliubov minima are diagonalized after constructing the diabatic basis.
View full abstract
-
Kazuya YAMADA
Article type: Article
1991 Volume 83 Issue 4 Pages
D168-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Hirokazu AIBA
Article type: Article
1991 Volume 83 Issue 4 Pages
D169-D175
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
V. G. Zelevinsky
Article type: Article
1991 Volume 83 Issue 4 Pages
D176-D177
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Article type: Appendix
1991 Volume 83 Issue 4 Pages
App2-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Article type: Appendix
1991 Volume 83 Issue 4 Pages
App3-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Article type: Cover
1991 Volume 83 Issue 4 Pages
Cover2-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS
-
Article type: Cover
1991 Volume 83 Issue 4 Pages
Cover3-
Published: July 20, 1991
Released on J-STAGE: October 02, 2017
JOURNAL
FREE ACCESS