نتایج جستجو برای: deformed shell model
تعداد نتایج: 2157451 فیلتر نتایج به سال:
The explanation of the asymmetry in the fragment mass distributions of many actinide nuclei has long been a stumblestone in fission theory. Shortly after the advent of the shell model, Lise Meitner related the mass asymmetry to shell structure, in particular to magic nucleon numbers in one of the fragments. Indeed, since the classical liquid drop model (LDM) prefers symmetric shapes, the mass a...
We propose a simple quartet condensationmodel (QCM)which describes with very high accuracy the isovector pairing correlations in self-conjugate nuclei. The quartets have an α-like structure and are formed by collective isovector pairs. The accuracy of the QCM is tested forN = Z nuclei for which exact shell model diagonalizations can be performed. The calculations are done with two isovector pai...
The deformation barriers standing in the quasi-molecular shape path have been determined in the actinide region within a macroscopicmicroscopic energy derived from a generalized liquid drop model, the algebraic droplet model shell corrections and analytic expressions for the pairing energies. Double and triple-humped fission barriers appear. The second barrier corresponds to the transition from...
We present a review of recent applications of the relativistic mean-field theory to the structure of nuclei close to the drip-lines. For systems with extreme isospin values, the relativistic Hartree-Bogoliubov model provides a unified and self-consistent description of mean-field and pairing correlations. The model has been applied in studies of structure phenomena that include: formation of ne...
Protons and neutrons in the atomic nucleus move shells analogous to electronic shell structures of atoms. The nuclear structure varies as a result changes mean field with number N protons Z, these variations can be probed by measuring mass differences between nuclei. = Z 40 self-conjugate 80Zr is particular interest, its proton neutron are expected very similar, ground state highly deformed. He...
We consider the problem of constructing the middle surface of a deformed elastic shell from its first and second fundamental forms, âαβ and b̂αβ . The undeformed shell is a spherical cap of radius R and thickness h with an angular width 2θ0 where 0 < θ0 < π/2. The cap is subjected to a constant uniform load λ and is simply supported at its edge. We seek to compute the one–parameter families of b...
The low-lying states in 106Zr and 108Zr have been investigated by means of β-γ and isomer spectroscopy at the RI beam factory, respectively. A new isomer with a half-life of 620±150 ns has been identified in 108Zr. For the sequence of even-even Zr isotopes, the excitation energies of the first 2+ states reach a minimum at N = 64 and gradually increase as the neutron number increases up to N = 6...
09 v 1 4 A ug 2 00 0 On the Solution of the Number - Projected Hartree - Fock - Bogoliubov Equations
The numerical solution of the recently formulated number-projected Hartree-Fock-Bogoliubov equations is studied in an exactly soluble cranked-deformed shell model Hamiltonian. It is found that the solution of these number-projected equations involve similar numerical effort as that of bare HFB. We consider that this is a significant progress in the mean-field studies of the quantum many-body sy...
Intermediate-energy Coulomb excitation measurements are performed on the N ≥ 40 neutron-rich nuclei (66,68)Fe and (64)Cr. The reduced transition matrix elements providing a direct measure of the quadrupole collectivity B(E2;2(1)(+) → 0(1)(+)) are determined for the first time in (68)Fe(42) and (64)Cr(40) and confirm a previous recoil distance method lifetime measurement in (66)Fe(40). The resul...
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