Interpretation of the experimental evidence concerning the quadrupole moment of Bi²⁰⁹ — A test of the shell model

Abstract

Attempts are made to construct a model of the quadrupole moment of Bi²⁰⁹ which will be consistent with the hfs interaction constant and the Bi²⁰⁹-Pb²⁰⁸ isotone shift observed in muonic x-rays. We achieve good agreement by postulating that the Bi²⁰⁹ quadrupole moment is due to a single proton in anh _9/2 state and to a distorted Pb²⁰⁸ core which has a deformation of about 1%. The inferred quadrupole moment is found to be 0.37 barns of which 0.12 barns is due to the distorted core.