Pairing correlations in N~Z pf-shell nuclei

Abstract

We perform Shell Model Monte Carlo calculations to study pair correlations in the ground states of $N=Z$ nuclei with masses A=48-60. We find that $T=1$, $J^{\pi }=0^{+}$ proton-neutron correlations play an important, and even dominant role, in the ground states of odd-odd $N=Z$ nuclei, in agreement with experiment. By studying pairing in the ground states of ${}^{52-58}$Fe, we observe that the isovector proton-neutron correlations decrease rapidly with increasing neutron excess. In contrast, both the proton, and trivially the neutron correlations increase as neutrons are added. We also study the thermal properties and the temperature dependence of pair correlations for ${}^{50}$Mn and ${}^{52}$Fe as exemplars of odd-odd and even-even $N=Z$ nuclei. While for ${}^{52}$Fe results are similar to those obtained for other even-even nuclei in this mass range, the properties of ${}^{50}$Mn at low temperatures are strongly influenced by isovector neutron-proton pairing. In coexistence with these isovector pair correlations, our calculations also indicate an excess of isoscalar proton-neutron pairing over the mean-field values. The isovector neutron-proton correlations rapidly decrease with temperatures and vanish for temperatures above $T=700$ keV, while the isovector correlations among like nucleons persist to higher temperatures. Related to the quenching of the isovector proton-neutron correlations, the average isospin decreases from 1, appropriate for the ground state, to 0 as the temperature increases.

Cited by in corpus (28)

• Pairing in nuclear systems: from neutron stars to finite nuclei
• Local Density Approximation for proton-neutron pairing correlations. I. Formalism
• Overview of Neutron-Proton Pairing
• Cranked shell model and isospin symmetry near N=Z
• Pairing and symmetry energy in N \simeq Z nuclei
• Shell Model Monte Carlo studies of neutron-rich nuclei in the 1s-0d-1p-0f shells
• Competition of isoscalar and isovector proton-neutron pairing in nuclei
• Band termination in the N=Z Odd-Odd Nucleus 46V
• Quantum Monte Carlo simulation in the canonical ensemble at finite temperature
• Quasi-Deuteron Configurations in odd-odd N=Z nuclei
• Results from Shell Model Monte Carlo Studies
• Relation between Wigner energy and proton-neutron pairing
• Physical features of strength of isoscalar pairing interaction determined by relation between double charge change and double pair transfer
• Thermodynamical properties of a mean-field plus pairing model and applications for the Fe nuclei
• Proton-neutron interactions in N \approx Z nuclei
• Shell Model Monte Carlo Investigation of Rare Earth Nuclei
• Gamow-Teller excitations at finite temperature: Competition between pairing and temperature effects
• Isovector Pairing in Odd-A Proton-Rich Nuclei
• SMMC studies of N=Z pf-shell nuclei with pairing-plus-quadrupole Hamiltonian
• Isomeric cross sections of fast-neutron induced reactions on ${}^{197}$Au
• An Algebraic Pairing Model with Sp(4) Symmetry and its Deformation
• How to count nucleon pairs?
• Parity-Projected Shell Model Monte Carlo Level Densities for fp-shell Nuclei
• Symmetry Restoration in Mixed-Spin Paired Heavy Nuclei
• Dynamical symmetry of isobaric analog 0+ states in medium mass nuclei
• Ground state particle-particle correlations and double beta decay
• Constrained-Path Quantum Monte-Carlo Approach for Non-Yrast States Within the Shell Model
• Long-standing problem: The nuclear level density angular-momentum dependence and isomeric data assessment