Microscopic study of deformed neutron-deficient 124-132Ce isotopes

Abstract

Variation after Projection (VAP) calculations in conjunction with Hartree Bogoliubov (HB) ansatz have been carried out for 124−132 Ce mass chain. In this framework, the yrast spectra, B(E2) transition probabilities and occupation numbers for various shell model orbits have been obtained. The observed decrease in deformation in going from 124 Ce to 132 Ce is seen to arise due to a slow decrease in the occupation of 1g 7/2 proton orbit and a systematic increase in the occupations of 2d 5/2 , 1g 7/2 and 1h 11/2 neutron orbits. Besides this, the experimental low-lying yrast spectra and B(E2) transition probabilities are reproduced with reasonable accuracy by using PQOH interaction. I IntroductionAn inspection of the recent experimental data [1-10], for example the energy level spacings and the lifetimes of excited states in the light neutron-deficient Cerium (Ce) nuclei reveals a region of pronounced collective behavior. The experimental data [1][2][3][4][5] ) as an effect of h 11/2 neutron alignment process. It has been found that theoretical attempts have been made by many authors to study specific nuclei and there is a lack of microscopic calculation to study the low-lying systematics of the entire neutron-deficient part of Ce isotopic mass chain in a single framework. It is with this motivation to study the low-lying systematics of the neutron-deficient isotopes that we plan to study these nuclei in a suitable calculational framework.In the present paper an attempt has been made to carry out a microscopic study of the yrast states and B(E2) transition probabilities in the neutron-deficient 124−132 Ce, by employing the VAP [13] formalism in conjunction with the HB [14] ansatz for the axially symmetric wave functions. For the calculation of yrast levels, the pairing plus-quadrupolequadrupole-plus-octupole-octupole plus-hexadecapolehexadecapole (PQOH) model of effective interaction in a valence space spanned by 3s 1/2 , 2d 3/2 , 2d 5/2 , 2f 7/2 , 1g 7/2 , 1h 9/2 , 1h 11/2 and 1i 13/2 orbits for protons as well as neutrons is employed. The 100 Sn is considered as an inert core. II Calculational details II.1 The one and two body parts of the HamiltonianThe spherical single-particle energies (S.P.E.'s) that we have employed are (in MeV): (2d 5/2 ) = 0.0, (3s 1/2 ) = 1.4, (2d 3/2 ) = 2.0, (1g 7/2 ) = 4.0, (1h 11/2 ) = 6.5, (2f 7/2 ) = 13.0, (1h 9/2 ) = 14.0 and (1i 13/2 ) = 15.5. The S.P.E.'s of 2d 5/2 , 3s 1/2 , 2d 3/2 , 1g 7/2 and 1h 11/2 are nearly the same as that employed by Vergados and Kuo [15] as well as

Cranking study of low lying yrast spectra and deformation systematics in some even-even neutron-deficient [sup 130-136]Nd

“…(1-4), the yrast spectra for 130-136 Nd isotopes is displayed, where we have compared the experimental values of yrast states with the theoretical values (th.1 & th.2). The spectra corresponding to th.1 have been obtained by using Cranked-Hartree-Fock-Bogoliubo (CHFB) framework of calculations whereas spectra corresponding to th.2 [22] have been obtained by using Variation-After -Projection (VAP) technique. It turns out from our , E 4 + / E 2 + and intrinsic quadrupole moments leads to the conclusion that deformation decreases as one moves from 130 Nd to 136 Nd.…”