Electric Quadrupole Transitions of Some Even-Even Neon Isotopes

The reduced electric quadrupole transition strengths B(E2) from the first excited 2^+ state to the ground 0^+ state of some even-even Neon isotopes (18,20,22,24,26,28Ne) have been calculated. All studied isotopes composed of 16O nucleus that is considered as an inert core and the other valence particles considered to move over the sd-shell model space within 1d5/2, 2s1/2 and 1d3/2 orbits. The configuration mixing shell model with limiting number of orbitals in the model space outside the inert core fail to reproduce the measured electric transition strengths. Therefore, and for the purpose of enhancing the calculations, the discarded space has been included through a microscopic theory which considers a particle-hole excitations from the core orbits and from the model space orbits into the higher orbits with 2hω excitations. These effects are called core-polarization effects. The transition strengths have been calculated with effective nucleon charges deduced from the core polarization calculations, and calculated with standard effective nucleon charges e p^eff = 1.3 e for the proton and e n^ eff = 0.5 e for neutron. The calculations are based on sd-shell model space with USDB interactions. The harmonic oscillator potential is used to generate the single particle matrix elements, where the value of the size parameter b is adjusted to get the experimental root mean square matter radii for each isotope.