Speaker
Description
Nuclides in the A ≈ 80 mass region provide an important testing ground for shape coexistence driven by sub-shell gaps and configuration mixing. The nucleus ⁸⁰Sr is predicted to exhibit coexisting shapes at low excitation energy [1], but experimental information on non-yrast states and excited 0⁺ levels remain limited. The first excited 0⁺ state has been tentatively assigned near 1 MeV in evaluated data (NNDC) [2], based on the ⁷⁸Kr (³He, n) two-proton transfer reaction [3].β-decay spectroscopy provides complementary information needed to confirm these assignments.
The collective structure of ⁸⁰Sr is investigated using β⁺/EC decay of ⁸⁰Y. The data were obtained at the ISOLDE Decay Station (IDS) at CERN, during requested yield measurements preceding the approved experiment on ⁸⁰Y and ⁸²Y decays. The setup included eight HPGe clover detectors for γ-ray spectroscopy, LaBr₃(Ce) detectors for fast timing, a plastic scintillator for β detection, and a geometry suitable for γ–γ angular correlation measurements. These data allow β–γ–γ coincidence analysis, angular correlation and lifetime measurements of excited states. The SPEDE electron spectrometer was part of the approved proposal [4] but was commissioned only in October 2025, and the full experiment will be performed when beam time becomes available.
Gamma-ray transitions were identified and coincidence relationships established to search for low-lying non-yrast states, and a partial level scheme of ⁸⁰Sr has been constructed. Contamination from ¹¹⁸I decay was observed, and a partial level scheme for ¹¹⁸Te was therefore built, with several previously unreported transitions and levels assigned to this nucleus.
Ongoing work includes γ–γ angular correlation analysis and lifetime measurements in ⁸⁰Sr to determine spins and multipolarities. Participation in the planned workshop will provide essential training in angular-correlation and fast-timing techniques required to complete this analysis.
References:
[1] J. Döring, K. Heyde, M. Hannawald, et al. Low-spin states from decay studies in the mass 80 region. The European Physical Journal A 7(4) (2000) 507–515. https://doi.org/10.6028/jres.105.006
[2] National Nuclear Data Center (NNDC). Chart of Nuclides & Level Schemes (2023). Brookhaven National Laboratory. https://www.nndc.bnl.gov
[3] W.P. Alford, J. Cerny, B.G. Harvey, et al. A study of the (3He, n) reaction on isotopes of Krypton, Nuclear Physics A 330 (1979) 77–90. https://doi.org/10.1016/0375-9474(79)90538-4
[4] Proposal to the ISOLDE and Neutron Time-of-Flight Committee https://cds.cern.ch/record/2731976/files/INTC-P-586.pdf