Probing the nucleus by peeling it - 22 Mai 2009

In the nuclei of atoms, nucleons (protons and neutrons) may pair together. Understanding this phenomenon, its origin and effects on the properties of nuclei, is one of the major objectives of nuclear physics research.
To study the pairing of nucleons, physicists generate collisions between nuclei in accelerators such as the GANIL facility. During a collision, one or more nucleons may be torn off the nuclei. Physicists use the breakup reactions during which two nucleons are torn apart to probe properties such as the size or shape of the nucleon pairs. However, a link is still needed between the pairing of nucleons in the nucleus and their characteristics, once they have been removed from the nucleus. It is this link that the two research scientists working at GANIL and IPN-Orsay have clearly established, by proposing a theoretical model allowing the evolution of two nucleons to be followed, from their initial strongly correlated state to their detection outside the nucleus.
"We applied our model to the case where two neutrons are torn from a nucleus" say the authors of this work. "The model shows that depending on the relative emission angle of the two neutrons, it is possible, by reversing the breakup reaction 'movie', to determine the spatial characteristics of the neutron pair within the nucleus. This allows us to better interpret the results of breakup experiments in the study of stable and exotic nuclei and, in particular, to map the spatial correlations of the nucleons in such systems."
 

This theoretical advance is to be published in Physical Review Letters.
Publication 
Reference: Marlène Assié and Denis Lacroix, to be published in Physical Review Letters, May 2009.