Extension of the multiphonon method to odd mass deformed nuclei

The multiphonon method based on one type of phonon is extended to odd mass nuclei. The formulas for the matrix elements of one and two body operators are given.     

Removal of redundancy from the single particle equation of motion method for odd mass nuclei

A method is developed for the removal of redundancy which is known to plague the calculation of low lying spectra of odd mass nuclei by the equation of motion method. The feasibility of the method is verified numerically.     

Level density for doubly odd deformed nuclei

The level density for doubly odd deformed nuclei near B_n is calculated within the framework of the semi-microscopic approach. The calculated values are found to be in good agreement with the experimental ones. It is shown that for the I ? 1 states it is important to take into account rotational motion.     

Particle-rotor model for doubly odd transitional nuclei of the Tl-region

A model has been investigated describing a situation in which two noninteracting high-j Nilsson-BCS quasiparticles move in the deformed field of an axially and reflection symmetric rotor. According to the positions of thej-shells with respect to the proton and neutron Fermi surfaces structures of different character emerge referred to as semi- and doubly-decoupled. In particular, strongly Coriolis-distorted bands recently reported in doubly odd Tl nuclei are discussed. Also \(\tilde \pi h_{9/2} \) bands in neighbouring odd mass Tl isotopes are analysed on the same footing. It is shown that the pronounced odd even staggering of the transition energies can be understood as a specific quantal feature associated with the Coriolis interaction.     

Signature effects in odd mass ytterbium nuclei in an angular momentum projected Hartree-Fock analysis

We explain the signature effects in the spectrum of odd mass Yb nuclei in a projected Hartree-Fock calculation without assuming gamma asymmetry. Rotation-alignment of nucleons in largej orbits is responsible for the signature dependence in energy and transition rates.     

Reaction cross sections for collisions involving exotic light nuclei within the glauber approach

The reaction cross sections for the interaction of exotic nuclei ⁶He and ¹¹Li with ¹²C nuclei are calculated for energies of about 0.8 GeV per nucleon. The cross sections calculated by the exact Glauber formula are compared with their counterparts found by using the formulas of the optical limit, the rigidtarget approximation, and the few-body approximation. The effect of the structure of the nuclei being considered on the calculated cross sections is examined. The root-mean-square radii of the ⁶He and ¹¹Li nuclei are estimated on the basis of experimental data on the cross sections for the interaction of these exotic nuclei with ¹²C nuclei.     

Mean-field derivation of the interacting boson model Hamiltonian and exotic nuclei

A novel way of determining the Hamiltonian of the interacting boson model (IBM) is proposed. Based on the fact that the potential energy surface of the mean-field model, e.g., the Skyrme model, can be simulated by that of the IBM, parameters of the IBM Hamiltonian are obtained. By this method, the multifermion dynamics of surface deformation can be mapped, in a good approximation, onto a boson system. The validity of this process is examined for Sm and Ba isotopes, and an application is presented to an unexplored territory of the nuclear chart, namely, the right lower corner of 208Pb.     

Angular distribution of photofission fragment of even-even and odd mass nuclei studies using SSNTD technique

Fission fragment angular distribution measurements of even-even (²³²Th) and odd mass (²³⁷Np) nuclei were carried out using bremsstrahlung radiation in the energy range 7.4 to 9.2 MeV from variable energy microtron at Mangalore University. In the present work SSNTD lexan polycarbonate films were used to detect the fission tracks from both even-even (²³²Th) and odd mass (²³⁷Np) nuclei. From the knowledge of track density formed from photofission reaction of ²³²Th and ²³⁷Np, angular distribution of fission fragments was measured. The results obtained are discussed on the basis of Age Bohr theory in this paper.     

A simple model for doublet bands in doubly odd nuclei

Nuclear structure of doublet bands in doubly odd nuclei with mass A ∼ 130 is investigated within the framework of a simple model where the even-even core couples with a neutron and a proton in intruder orbitals through a quadrupole-quadrupole interaction. The model reproduces quite well the energy levels of doublet bands and electromagnetic transitions. The staggering of the ratios B(M1;I → I - 1)/B(E2;I → I - 2) of the yrast bands turns out to be described by the chopsticks-like motion of two angular momenta of the unpaired neutron and the unpaired proton when they are weakly coupled with the core.-1 An erratum to this article is available at .     

On the interpretation of rotational bands in odd actinide nuclei

While the cranked quasiparticle model gives too large alignment of angular momentum for the ground state bands of ²³⁵U and ²³⁷Np, the empirical alignments are well reproduced in a quasiparticle plus rotor model with a rotation dependent interaction between core and quasiparticle. This model also gives better agreement with the data than a cranked quasiparticle model with Coriolis attenuation.     

Electromagnetic processes in light nuclei: Results within a microscopic approach

Results obtained by investigating the electrodisintegration of A = 3 and 4 nuclei and the photodisintegration of A = 3, 4, 6, and 7 nuclei on the basis of precise solutions to dynamical problems involving NN and NNN forces are presented. The role of NNN forces, final-state relativistic effects, the contribution of meson-exchange currents, an anomaly in electrodisintegration at high momentum transfers and low energy transfers, sensitivity to nuclear dynamics in the exclusive electrodisintegration of ⁴He nuclei, and the soft-mode resonance in the photodisintegration of ⁶He nuclei are considered.     

Giant resonances in exotic spherical nuclei within the RPA approach with the Gogny force

Theoretical results for giant resonances in the three doubly magic exotic nuclei ⁷⁸Ni, ¹⁰⁰Sn and ¹³²Sn are obtained from Hartree-Fock (HF) plus Random Phase Approximation (RPA) calculations using the D1S parameterization of the Gogny two-body effective interaction. Special attention is paid to full consistency between the HF field and the RPA particle-hole residual interaction. The results for the exotic nuclei, on average, appear similar to those of stable ones, especially for quadrupole and octupole states. More exotic systems have to be studied in order to confirm such a trend. The low energy of the monopole resonance in ⁷⁸Ni suggests that the compression modulus in this neutron-rich nucleus is lower than the one of stable ones.     

New coupling limit for odd nuclei and truncated analog of Stephens basis

In the SU(3) limit of PTQM for particular intermediate particle-vibration coupling strengths Γ = ±Γ_SUSY there arise two complementary coupling limits, denoted as SUSY and coherent-SUSY schemes. The coherent-SUSY pattern is a truncated analog of the Stephens rotation-aligned model and the question of the analog of SUSY-scheme in the rotational model seems still open.     

Liquid drop parameters for hot nuclei

Using the semi-classical extended Thomas-Fermi (ETF) density variational method, we derived self-consistently the liquid drop model (LDM) coefficients for the free energy of hot nuclear systems from a realistic effective interaction (Skyrme SkM¹). We expand the temperature (T) dependence of these coefficients up to the second order in T and test their application to the calculation of the fission barriers of the nuclei ²⁰⁸Pb and ²⁴⁰Pu.     

Multi-band spectra of odd and even nuclei of the s-d shell

The energy levels of^{21, 23}Na,^{22, 23}Ne,^{24, 28}Mg and^{25, 29}Al are obtained by mixing various bands using the projected deformed Hartree-Fock (DHF) method. Solutions having minimum energies are found to be prolate for all the nuclei considered here. Higher bands are obtained either by considering particle-hole excitations or oblate solutions. These various bands are mixed using the projection method and care has been taken to orthogonalize the bands. The interactions used in this study are those given by Kuo, Preedom-Wildenthal (PW) and WHMK interactions. The last one seems to give good results for most of the nuclei considered here. Not only are the lowest bands well-reproduced but the second lowest bands agree reasonably well in most nuclei. The third lowest ones obtained in some nuclei are not yet observed as complete bands. However, K obtained for the third band seems to be correct. A comparison with shell model calculations—which are numerically exhausting—shows similar results for the lowest band. However, the agreement of the second band varies from nucleus to nucleus. A comparison between matrix elements of the interactions is made to analyze the results.