E2 rotational invariants of 0$$^{+}_{1}$$ and 2$$^{+}_{1}$$ states for ¹⁰⁶Cd: The emergence of collective rotation

Journal Article · Tue Nov 01 00:00:00 EDT 2022 · Physics Letters. B

DOI:https://doi.org/10.1016/j.physletb.2022.137446· OSTI ID:1888087

Gray, T. J.; Allmond, J. M.; Janssens, R. V.F.; Korten, W.; Stuchbery, A. E.; Wood, J. L.; Ayangeakaa, A. D.; Bottoni, S.; Bucher, B. M.; Campbell, C. M.; Carpenter, M. P.; Crawford, H. L.; David, H.; Doherty, D. T.; Fallon, P.; Febbraro, M. T.; Galindo-Uribarri, A.; Gross, C. J.; Komorowska, M.; Kondev, F. G. ; Lauritsen, T.; Macchiavelli, A. O.; Napiorkowsi, P.; Padilla-Rodal, E.; Pain, S. D.; Reviol, W.; Sarantites, D. G.; Savard, G.; Seweryniak, D.; Wu, C. Y.; Yu, C. -H.; Zhu, S.

The collective structure of ¹⁰⁶Cd is elucidated by multi-step Coulomb excitation of a 3.849 MeV/A beam of ¹⁰⁶Cd on a 1.1 mg/cm^{2 208}Pb target using GRETINA-CHICO2 at ATLAS. Fourteen E2 matrix elements were obtained. The nucleus ¹⁰⁶Cd is a prime example of emergent collectivity that possesses a simple structure: it is free of complexity caused by shape coexistence and has a small, but collectively active number of valence nucleons. This work follows in a long and currently active quest to answer the fundamental question of the origin of nuclear collectivity and deformation, notably in the cadmium isotopes. The results are discussed in terms of phenomenological models, the shell model, and Kumar-Cline sums of E2 matrix elements. The < 0$$^{+}_{2}$$ ||E2||2$$^{+}_{1}$$ > matrix element is determined for the first time, providing a total, converged measure of the electric quadrupole strength, < Q² >, of the first-excited 2$$^{+}_{1}$$ level relative to the 0$$^{+}_{1}$$ ground state, which does not show an increase as expected of harmonic and anharmonic vibrations. Strong evidence for triaxial shapes in weakly collective nuclei is indicated; collective vibrations are excluded. This is contrary to the only other cadmium result of this kind in ¹¹⁴Cd by C. Fahlander et al., Nucl. Phys. A485, 327 (1988), which is complicated by low-lying shape coexistence near midshell.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States); Duke Univ., Durham, NC (United States). Triangle Universities Nuclear Laboratory; Idaho National Laboratory (INL), Idaho Falls, ID (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of North Carolina, Chapel Hill, NC (United States)
• Sponsoring Organization: Australian Research Council; USDOE; USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Nuclear Physics (NP)
• Grant/Contract Number: AC02-05CH11231; AC02-06CH11357; AC05-00OR22725; AC07-05ID14517; AC52-07NA27344; FG02-97ER41033; FG02-97ER41041; SC0014442
• OSTI ID: 1888087
• Alternate ID(s): OSTI ID: 1888300; OSTI ID: 1888931; OSTI ID: 1899172; OSTI ID: 1907678; OSTI ID: 1969283
• Report Number(s): INL/JOU-22-67151-Rev000; LLNL-JRNL-833884; 1052178
• Journal Information: Physics Letters. B, Journal Name: Physics Letters. B Vol. 834; ISSN 0370-2693
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Collective Model
Collective model
Coulomb Excitation
Coulomb excitation
Electromagnetic Moments
Electromagnetic moments
Shell Model
Shell model
Sum Rules
Sum rules