When atomic nuclei collide they may fuse to form a single composite system, allowing us to make exotic new elements and investigate their structure. However, measured fusion probabilities for light nuclei such as 7Li and 9Be are much smaller than predicted. These nuclei often have strong cluster structure – they can be regarded as being composed of other light nuclei such as deuterons, tritons and α particles, weakly bonded together. In addition to fusion, other sorts of nuclear reaction can also then occur, which causes the light projectiles to disintegrate into their cluster constituents: breakup reactions. They make it very difficult for fusion reactions to happen.
Where this breakup process happens is crucial: only if the nuclei are approaching each other will it prevent fusion. With interaction timescales of the order of zeptoseconds (10-21 s), understanding the dynamics of the reaction is a major challenge. Recent experiments at the ANU Heavy Ion Accelerator Facility have shown that the energy and angular correlations of the breakup fragments can reveal detailed information about the location of breakup. A number of factors will affect where breakup occurs, including the collision energy, tidal forces, low-energy nuclear structure, and quantum tunnelling. Modelling these effects is key to interpreting ANU experimental results and understanding the possible influence of these reactions on fusion.
The student will have the opportunity to develop computer programs designed to model these complex processes, and to analyse data measured at the ANU Heavy Ion Accelerator Facility.