Thursday 6 June 2019, 2.00PM
Speaker(s): Augusto Macchiavelli, Lawrence Berkeley National Laboratory, USA
The effect of weak binding on nuclear structure, decay, and reactions is an open question in nuclear physics. On the neutron-rich side of stability, as the neutron separation energy approaches zero, weakly bound neutrons in the single-particle levels at the Fermi surface approach the edge of the nuclear potential and may move outside the core of well-bound nucleons, and possibly couple to unbound continuum states. The nature of this transition from a “closed” to an “open” quantum system , where binding is dominated by correlations rather than the mean field, has only just begun to be explored, and our understanding of weak-binding effects and coupling to the continuum is, in many ways, nascent.
The first spectroscopic study of the near drip-line Nucleus 40Mg, revealed two γ-ray transitions that suggest an excitation spectrum with unexpected properties as compared to both the systematics along the lighter Mg isotopes and available state-of-the-art theoretical model predictions. We will discuss a possible explanation for the observed structure in terms of weak-binding effects.
In 1956 Kerman published a seminal paper on rotational perturbations in nuclei . In the second part of the talk, we consider Kerman’s problem when one of the single-particle levels involved is a resonant state. We will present some preliminary results showing the behavior of the moment of inertia and the decoupling parameter as a function of the state width.
 J. Dobaczewski, et al. Prog. Part. Nucl. Phys. 59, 432 (2007).
 H. L. Crawford, et al. Phys, Rev. Lett. 122, 052501 (2019).
 A. Kerman, Mat. Fys. Medd. Dan. Vid. Selsk., no. 15 (1956).
*This material is based upon work supported by the U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract No. DEAC0205CH11231.