Core of F 25 studied by the F 25 (-p) proton-removal reaction

H. L. Crawford*, A. O. Macchiavelli, P. Fallon, D. Bazin, P. C. Bender, B. A. Brown, C. M. Campbell, M. Cromaz, B. Elman, A. Gade, J. D. Holt, R. V.F. Janssens, B. Longfellow, S. Paschalis, M. Petri, A. L. Richard, M. Salathe, J. A. Tostevin, D. Weisshaar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The Be9(BeF25(5/2+),BeO24)X proton-removal reaction was studied at the NSCL using the S800 spectrometer. The experimental spectroscopic factor for the ground-state to ground-state transition indicates a substantial depletion of the proton d5/2 strength compared to shell-model expectations, similar to the findings of an inverse-kinematics (p,2p) measurement performed at RIBF. The BeF25 to BeO24 ground-states overlap is considerably less than anticipated if the core nucleons behaved as rigid, doubly-magic BeO24 within BeF25. We interpret the new results within the framework of the Particle-Vibration Coupling (PVC) model, of a d5/2 proton coupled to a quadrupole phonon of an effective core. This approach provides a good description of the experimental data, requiring an effective BeO∗24 core with a phonon energy of ħω2= 3.2 MeV and a B(E2)≈2.7 W.u. - softer and more collective than a bare BeO24. Both the Nilsson deformed mean field and the PVC models appear to capture the properties of the effective core of BeF25, suggesting that the additional proton polarizes BeO24 in such a way that it becomes either slightly deformed or a quadrupole vibrator.

Original languageEnglish
Article numberL061303
Number of pages6
JournalPhysical Review C
Issue number6
Publication statusPublished - 5 Dec 2022

Bibliographical note

Funding Information:
Acknowledgments. We would like to thank the operations team at NSCL for their work in beam delivery during the experiment. A.O.M. would like to thank Roberto Liotta for discussions on particle-vibration-coupling. GRETINA was funded by the U.S. DOE Office of Science. Operation of the array at NSCL was supported by DOE under Grants No. DE-SC0014537 (NSCL) and DE-AC02-05CH11231 (LBNL). This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contracts No. DE-AC02-05CH11231 (LBNL) and No. DE-AC05-00OR22725 (ORNL), and Grants No. DE-SC0020451 (NSCL), No. DE-FG02-97ER41041 (UNC), and No. DE-FG02-97ER41033 (TUNL). Support also came from the U.S. National Science Foundation (NSF) under Cooperative Agreement No. PHY-1565546 (NSCL). This work was also supported by the UK STFC under Contracts No. ST/V001108/1, No. ST/P003885/1, and No. ST/L005727/1. M.P. acknowledges support by the Royal Society.

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© 2022 American Physical Society.

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