Speaker
Description
In this talk, we will discuss some aspects of the structure of neutron-rich F nuclei within the framework of the particle plus rotor model. Specifically, the low-lying structure of 25,27,29F can be understood in the rotation-aligned coupling scheme with their 5/2+ ground states as the bandhead of a decoupled band [1,2].
The excitation energies of the 1/2+ and 9/2+ states correlate strongly with the rotational energy of the effective core, seen by the odd proton, and allow us to estimate its 2+ energy. The Nilsson plus PRM picture suggests that the extra proton, with a dominant component in the down-sloping [220] 1⁄2 level polarizes the Oxygens and stabilizes its dynamic deformation. Thus, the effective cores could be interpreted as slightly deformed rotors with a modest e2 ≈ 0.15, as compared to the weak vibrational quadrupole collectivity in the real Oxygens.
Relevant to this interpretation are the recent studies of the 25F(p,2p) 24O and 25F(-1n KO)24O reactions carried out at RIBF/RIKEN [3] and NSCL/MSU [4] respectively. Derived spectroscopic factors suggest that the effective core of 25F significantly differs from a free 24O nucleus. The observed fragmentation of the πd5/2 single-particle strength agrees with the PRM calculations and arises from the effects of deformation and core overlap.
We will also present results of the two-particles plus rotor model for odd-odd 28F [5] and 30F [6] and discuss further experiments that can shed further light on the validity of our interpretation.
*This material is based upon work supported by the U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract No. DE-AC05-00OR22725
[1] A.O. Macchiavelli, H.L.Crawford, P.Fallon, et al. , Phys. Lett. B775,160(2017).
[2] A.O. Macchiavelli, R. M. Clark, H. L.Crawford, et al., Phys. Rev. C102, 041301(R) (2020).
[3] T.L.Tang, T.Uesaka, S.Kawase, et al. Phys. Rev. Lett. 124, 212502 (2020).
[4] H.L.Crawford, M.D.Jones, A.O.Macchiavelli, et al., Phys. Rev. C106 L061303 (2022).
[5] A. Rebel, O. Sorlin, F.M. Marques, et al., Phys. Rev. Lett. 124,152502 (2020).
[6] J. Kahlbow, PhD Thesis, Technische Universitat Darmstadt (2019).
