학술논문
The Core of $^{25}$F studied by the $^{25}$F(-1p)$^{24}$O reaction
Document Type
Working Paper
Author
Crawford, H. L.; Jones, M. D.; Macchiavelli, A. O.; Fallon, P.; Bazin, D.; Bender, P. C.; Brown, B. A.; Campbell, C. M.; Clark, R. M.; Cromaz, M.; Elman, B.; Gade, A.; Holt, J. D.; Janssens, R. V. F.; Lee, I. Y.; Longfellow, B.; Paschalis, S.; Petri, M.; Richard, A. L.; Salathe, M.; Tostevin, J. A.; Weisshaar, D.
Source
Subject
Language
Abstract
The $^{25}$F($5/2^+) (-1p) ^{24}$O 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 $d_{5/2}$ strength compared to shell-model expectations. Our result supports the findings reported by Tang \textit{et al.}, from their study of the $(p,2p)$ reaction at RIBF. The overlap between the $^{25}$F and $^{24}$O ground-states is considerably less than anticipated if $^{24}$O acted as a robust and rigid doubly-magic core in $^{25}$F. We interpret the results within the framework of the Particle-Vibration Coupling (PVC) of a $d_{5/2}$ proton coupled to a quadrupole phonon of an effective core. This approach provides a good description of the experimental data by requiring an effective $^{24}$O* core with a phonon energy of $\hbar\omega_2$= 3.2 MeV, and a $B(E2) ~ 2.7$ W.u., softer and more collective than a bare $^{24}$O. Both the Nilsson deformed mean field and the PVC models appear to capture the properties of the effective core of $^{25}$F, suggesting that the additional proton tends to polarize the free, doubly magic $^{24}$O in such a way that it becomes either slightly deformed or a quadrupole vibrator.
Comment: 6 pages, 2 figures
Comment: 6 pages, 2 figures