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While the phenomenon of one- and two-neutron ground-state halo nuclei is well established, the effects of weak binding on nuclear excitation properties remain largely unexplored. Motivated by this question and by recent data in 40Mg we investigate the coupling of weakly bound (halo) valence neutrons to a core using the known properties of 40Mg to explore and illustrate possible particle-core coupling schemes and their impact on the low-lying excitation spectrum.

We discuss a phenomenological shell model analysis of the structure of 48 , 49 , 50Ca. Based on simple arguments, we propose wavefunctions fit to the available data on spectroscopic factors derived from direct one neutron addition and removal reactions. These empirical wavefunctions are then used to calculate properties of low-lying states in 49 , 50 , 51Ca, which are consistent with available experimental data. Our analysis appears to capture the main ingredients at play in the low-lying properties of these nuclei and emphasize the prominent role of pairing correlations. We also present predictions that could motivate further work.

A new experimental setup to measure prompt-delayed γ-ray coincidences from isotopically identified fission fragments, over a wide time range of 100ns-200μ s, is presented. The fission fragments were isotopically identified, on an event-by-event basis, using the VAMOS++ large acceptance spectrometer. The prompt γ rays emitted at the target position and corresponding delayed γ rays emitted at the focal plane of the spectrometer were detected using, respectively, thirty two crystals of the AGATA γ-ray tracking array and seven EXOGAM HPGe Clover detectors. Fission fragments produced in fusion and transfer-induced fission reactions, using a 238U beam at an energy of 6.2 MeV/u impinging on a 9Be target, were used to characterize and qualify the performance of the detection system.