Isovector pairing in odd-A proton-rich nuclei
نویسندگان
چکیده
A simple model based on the group SO(5) suggests that both the likeparticle and neutron-proton components of isovector pairing correlations in odd-A nuclei are Pauli blocked. The same effect emerges from Monte Carlo Shell-model calculations of proton-rich nuclei in the full fp shell. There are small differences between the two models in their representation of the effects of an odd nucleon on the competition between like-particle and neutron-proton pairing, but they can be understood and reduced by using a two-level version of the SO(5) model. On the other hand, in odd-odd nuclei with N 6= Z, SO(5) disagrees more severely with the shell model because it incorrectly predicts ground-state isospins. The shell model calculations for any fp-shell nuclei can be extended to finite temperature, where they show a decrease in blocking.
منابع مشابه
Pairing and isospin symmetry in proton-rich nuclei
Unlike their lighter counterparts, most odd-odd N = Z nuclei with mass A > 40 have ground states with isospin T=1, suggesting an increased role for the isovector pairing interaction. A simple SO(5) seniority-like model of this interaction reveals a striking and heretofore unnoticed interplay between likeparticle and neutron-proton isovector pairing near N = Z that is reflected in the number of ...
متن کامل- th / 9 61 00 06 v 1 3 O ct 1 99 6 Pairing correlations in N ∼ Z pf - shell nuclei
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 π = 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...
متن کاملar X iv : n uc l - th / 0 40 70 86 v 1 2 3 Ju l 2 00 4 Staggering behavior of 0 + state energies in the Sp ( 4 ) pairing model
We explore, within the framework of an algebraic sp(4) shell model, discrete approximations to various derivatives of the energies of the lowest isovector-paired 0 states of atomic nuclei in the 40 ≤ A ≤ 100 mass range. The results show that the symplectic model can be used to successfully interpret fine structure effects driven by the proton-neutron (pn) and like-particle isovector pairing int...
متن کاملQuartet condensation and isovector pairing correlations in N = Z nuclei
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...
متن کاملAn Algebraic Pairing Model with Sp(4) Symmetry and its Deformation
A fermion realization of the compact symplectic sp(4) algebra provides a natural framework for studying isovector pairing correlations in nuclei. While these correlations manifest themselves most clearly in the binding energies of 0 ground states, they also have a large effect on the energies of excited states, including especially excited 0 states. In this article we consider non-deformed as w...
متن کامل