Selected Publications: Low-temperature triple-alpha rate in a full three-body nuclear model, N. B. Nguyen, F. M. Nunes, I. J. Thompson, and E. F. Brown, Phys. Rev. Lett. 109 141101 (2012).
The magic nature of 132Sn explored through the single-particle states of 133Sn, K.L. Jones et al., Nature, 465 , 454-457 (27 May 2010)
Benchmark on neutron capture extracted from (d,p) reactions. A.M. Mukhamedzhanov, F.M. Nunes and P. Mohr, Phys. Rev. C 77 051601 (2008)
ÂExtracting (n,g) direct capture cross sections from Coulomb Dissociation: application to 14C(n,g)15CÂ N.C Summers and F.M. Nunes, Phys. Rev. C 78 011601 (2008)
B(E1) strengths from the Coulomb excitation of 11Be N. Summers et al., Phys. Lett. B 650, 124 (2007)
Scaling and interference in the dissociation of halo nuclei, M.S. Hussein, R. LichtenthÃ¤ler, F.M. Nunes and I.J. Thompson, Phys. Lett. B 640, 91 (2006)
Extended continuum discretized coupled channels method: Core excitation in the breakup of exotic nuclei, N. C. Summers, F. M. Nunes, and I. J. Thompson, Phys. Rev. C 74, 014606 (2006)
I study direct nuclear reactions and structure models that are useful in the description of reactions. Unstable nuclei are mostly studied through reactions, because they decay back to stability (often lasting less than a few seconds). My work focuses on developing models for reactions with exotic unstable nuclei. Reaction theory is very important because it makes the connection between experiments such as the ones performed at NSCL, and the nuclear structure information we want to extract. Within the realm of direct reactions, my contributions have been toward understanding inelastic excitation, breakup and transfer reactions.
The motivation to study these reactions are three-fold. Breakup and transfer reactions can be used as indirect methods to obtain capture rates of astrophysical relevance. These capture rates enter in the simulations of stars, and explosive sites such as novae and supernovae. In addition, reliable models for some specific direct reactions are crucial for nuclear waste management. Finally, and most importantly, we also need reactions to unveil the hidden secrets of the effective nuclear force which binds some exotic systems and not others.
Nuclei are many body systems of large complexity. Describing a reaction while retaining all the complexity of the projectile and target nuclei would be a daunting task. Fortunately, to describe many direct reactions, only a few structure degrees of freedom are necessary. Thus we develop simplified few-body structure models which retain the important features of the nucleus of interest and can be used as input to the reaction calculations. When comparing with the data, we learn whether our initial assumptions were correct. Given that many unstable nuclei break up so easily, the nucleus can go through the continuum (scattering states) in the reaction. Introducing breakup accurately involves computer intensive calculations, so we use the High Performance Computers at MSU.
When there are too many neutrons or protons in a nucleus, strange things happen. An example is shown in the figure: 11Li is a nucleus with 8 neutrons but only 3 protons. It has a central core but has two valence neutrons which hang loosely to the 9Li core, in an orbital of the size of Pb. If we remove any of the bodies (the core or either neutrons), the system falls apart. This is a characteristic also seen in Borromean rings. It means that the binding of the valence neutrons to the core is very, very subtle. Albeit the efforts developed over the last 20 years since the appearance of radioactive beam facilities, the effective force that keeps unstable systems together (whether it is 11Li or 100Sn) still has hidden secrets to unveil.