Seminarium Fizyki Jądra Atomowego

Nuclear structure is characterized by an interplay between single particle and collective phenomena. Apart from rotational and vibrational excitations certain nuclei exhibit another type of collective motion called clustering, such as e.g. seen in the 3α-structure of 12C. This is reflected in the spectrum of exited states, which contains both cluster rotational bands and shell-model-like single particle states.Although 12C is one of the most studied of all nuclei many important aspects remain poorly understood: • What is the structure of the second exited state, the famous 0+ (7.65MeV) state? • Does this state sustain a rotational band? If so, are there resonances of importance for determining the rate of the astrophysical 3α-reaction rate? • What is the mechanism of the 3α-decay of states in 12C? What is the link between the decay mechanism and the structure of the decaying state? • What is the role of resonances and non-resonant continuum states in the description of observables related to continuum states of 12C?In the last two years a number of new results have come out, which are beginning to answer some of these questions [1]. In this talk I will discuss the recent results including my own approach of using either β-decay of γ-decay to selectively populate unbound states in 12C.[1] H.O.U. Fynbo and M. Freer, Physics 4, 94 (2011).