Speaker
Description
The evolution of nuclear shell structure at the interface between the p and sd shells remains a central problem in nuclear physics, where cross-shell excitations and proton–neutron correlations drive changes in nuclear structure. The odd–odd nucleus 22F lies just above the Z=8 shell closure and is particularly sensitive to excitations across the p–sd shell gap, making it an ideal system for probing this transition region.
Excited states in 22F were populated via the 9Be(18O, αp)22F fusion–evaporation reaction using a 55 MeV beam delivered by the ATLAS facility at Argonne National Laboratory. Prompt γ rays were detected with the GRETINA array in coincidence with recoils identified by the Fragment Mass Analyzer. Doppler-corrected γ-γ coincidence measurements enabled the construction of an expanded level scheme.
Several previously unobserved γ-ray transitions and new excited states were identified, significantly extending the known spectroscopy of 22F. Spin and parity assignments were constrained through angular distribution and linear polarization measurements, providing new insight into the structure of this odd–odd system.
The results are compared with ab initio calculations based on chiral effective field theory and place new constraints on the description of proton–neutron correlations and shell evolution at the p–sd boundary.