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Shape Evolution in Neutron-Rich Krypton Isotopes Beyond N=60: First Spectroscopy of ^{98,100}Kr.
F Flavigny1, P Doornenbal2, A Obertelli2,3
1Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, Université Paris-Saclay, 91406 Orsay Cedex, France.
Physical Review Letters
|July 1, 2017
Summary
We measured gamma-ray energies in neutron-rich Krypton isotopes, revealing increased nuclear deformation beyond N=60. This deformation transition occurs at a different neutron number than in neighboring isotopes, suggesting shape coexistence.
Area of Science:
- Nuclear Physics
- Spectroscopy
- Nuclear Structure
Background:
- Neutron-rich isotopes near closed shells exhibit unique nuclear properties.
- The N=60 isotones show a rapid onset of deformation, a phenomenon studied in various isotopic chains.
- Understanding shape coexistence in nuclei provides insights into nuclear forces and structure.
Purpose of the Study:
- To investigate the low-lying states of neutron-rich Krypton isotopes (Kr-98, Kr-100).
- To determine the onset of deformation and explore shape coexistence in these isotopes.
- To compare the observed deformation trends with theoretical predictions and neighboring isotopic chains.
Main Methods:
- Utilizing gamma-ray spectroscopy.
- Employing (p,2p) reactions on Rubidium isotopes (Rb-99, Rb-101) at approximately 220 MeV/nucleon.
- Performing advanced theoretical calculations using beyond-mean-field methods with the Gogny D1S interaction.
Main Results:
- Observed a significant reduction in 21+ state energies in Kr-98 and Kr-100, indicating increased nuclear deformation beyond N=60.
- The onset of deformation in Krypton isotopes is shifted in neutron number compared to Strontium and Zirconium isotopes.
- Identified low-lying (02+, 22+) states in Kr-98, providing experimental evidence for competing configurations.
Conclusions:
- The results demonstrate a significant increase in deformation in neutron-rich Krypton isotopes beyond N=60.
- The observed deformation trend in Krypton isotopes differs from that in Strontium and Zirconium, highlighting isotopic effects.
- The experimental findings support theoretical predictions of shape coexistence in neutron-rich Krypton nuclei.
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