Testing the Mutually Enhanced Magicity Effect in Nuclear Incompressibility via the Giant Monopole Resonance in the $^{204,206,208}$Pb Isotopes

TL;DR

This study measures the giant monopole resonance in lead isotopes to test the proposed mutually enhanced magicity effect on nuclear incompressibility, finding no evidence for the effect and leaving the softness of open-shell nuclei unresolved.

Contribution

The paper provides experimental evidence that challenges the existence of the mutually enhanced magicity effect in nuclear incompressibility.

Findings

No manifestation of MEM effect in nuclear incompressibility

Results challenge previous explanations of nuclear softness

Open question remains about softness in open-shell nuclei

Abstract

Using inelastic $\alpha$-scattering at extremely forward angles, including $0^\circ$, the strength distributions of the isoscalar giant monopole resonance (ISGMR) have been measured in the $^{204,206,208}$Pb isotopes in order to examine the proposed mutually enhanced magicity (MEM) effect on the nuclear incompressibility. The MEM effect had been suggested as a likely explanation of the "softness" of nuclear incompressibility observed in the ISGMR measurements in the Sn and Cd isotopes. Our experimental results rule out any manifestation of the MEM effect in nuclear incompressibility and leave the question of the softness of the open-shell nuclei unresolved still.