Speaker
Description
Shell evolution in nuclei far from stability, such as those in the region of N ≥ 28 and Z < 20, is understood to arise from the complex interplay of orbital interactions, with different interactions accessible in unstable nuclei compared to stability. Experimental studies of these exotic regions provide stringent tests of modern shell model interactions, but are difficult to access experimentally. In this regard, the transfer reaction 47K(d,p)48K provides a unique opportunity to study the exotic pi(s1/2)-nu(fp) interaction in a near-doubly magic nucleus, owing to the pi(s1/2)^-1 ground state structure of 47K, which is near-degenerate with the `standard’ pi(d3/2)^-1 proton configuration in this region.
The first measurement of the 47K(d,p gamma)48K transfer reaction has been performed at GANIL, in inverse kinematics using a reaccelerated radioactive isotope beam. Heavy recoils, light ejectiles and prompt gamma-ray emissions were detected using the state-of-the-art MUGAST+AGATA+VAMOS experimental set-up. Through this work, the level scheme of 48K has been greatly extended with nine new bound excited states identified, spin-parities assigned and spectroscopic factors deduced. Detailed comparisons with SDPF-U and SDPF-MU shell-model calculations reveal a number of discrepancies between theory and experiment. Intriguingly, an apparent systematic overestimation of spectroscopic factors and a poor reproduction of the energies for 1− states suggests that the mixing between the pi(s1/2)^-1 and pi(d3/2)^-1 proton configurations in 48K is not correctly described using current interactions, challenging our descriptions of light nuclei around the N=28 island of inversion.
A complete analysis and discussion of the 47K(d,p gamma) reaction -- and the complementary 47K(d,t gamma) reaction -- will be presented.
