Decay path measurements for the 2.429 MeV state in Be9: Implications for the astrophysical α+α+n reaction

An experiment was performed at the Australian National University to study the Be9(Li6,Li6)Be9*→α+α+n reaction. This experiment was designed to study the breakup of Be9, in an attempt to quantify the contribution played by the He5+α and 8Be2++n channels for the low lying excited states. This information is required in order to resolve uncertainties in the α+α+n→ Be9 reaction rate in high-energy and neutron-rich astrophysical environments such as supernovae. Angular correlation measurements have been used to deduce that the 2.429 MeV state breaks up almost exclusively via the 8Be2+ channel. This method of identifying the break-up channel resolves the problem of distinguishing between the 8Be2+ and 5Heg.s. channels which are kinetically identical at this excitation energy.