Compressional-mode resonances in the molybdenum isotopes: Emergence of softness in open-shell nuclei near A=90

Abstract

"Why are the tin isotopes soft?" has remained, for the past decade, an open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the "doubly-closed shell" nuclei, ${}^{90}$Zr and ${}^{208}$Pb, overestimate the ISGMR energies of the open-shell tin and cadmium nuclei, by as much as 1 MeV. In an effort to shed some light onto this problem, we present results of detailed studies of the ISGMR in the molybdenum nuclei, with the goal of elucidating where--and how--the softness manifests itself between ${}^{90}$Zr and the cadmium and tin isotopes. The experiment was conducted using the ${}^{94,96,98,100}$Mo($\alpha ,{\alpha }^{\prime }$) reaction at $E_{\alpha }=386$ MeV. A comparison of the results with relativistic, self-consistent Random-Phase Approximation calculations indicates that the ISGMR response begins to show softness in the molybdenum isotopes beginning with $A=92$.

Accepted for publication to Physics Letters B

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• Bayesian inference of finite-nuclei observables based on the KIDS model
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• Isoscalar Giant Monopole Resonance in Spherical Nuclei as a Nuclear Matter Incompressibility Indicator
• Effect of ground-state deformation on the Isoscalar Giant Monopole Resonance and the first observation of overtones of the Isoscalar Giant Quadrupole Resonance in rare-earth Nd isotopes
• Nuclear incompressibility and its enduring impact on fusion cross-section
• Evolution of giant monopole resonance with triaxial deformation
• Monopole Excitation and Nuclear Compressibility: Present and Future Perspectives
• Performance of prototype Dual Gain Multilayer Thick GEM with high-intensity heavy-ion beam injections in low-pressure hydrogen gas
• Measurement of the isoscalar giant monopole resonance in ${}^{86}$Kr via deuteron inelastic scattering using an active target CAT-M