Sub-Coulomb Alpha Transfer Reactions

摘要

The a transfer reactions X(~6Li,d) and X(~7Li,t) can be used to probe the degree of a clustering in levels of the (X + α) compound nucleus. There are many cases in nuclear astrophysics where this information is crucial for predicting the the low-energy X + α cross section which in turn determines the reaction rate. A major advantage of using sub-Coulomb energies is that the results are largely independent of the assumed nuclear potential parameters. We have recently applied this technique to the ~(12)C(α,γ)~(16)O reaction, which is crucial for the understanding of He burning in massive stars. The ~(12)C(~6Li,d)~(16)O and ~(12)C(~7Li,t)~(16)O reactions populating the bound 2~+ and 1~- states of ~(16)O have been measured at energies below the Coulomb barrier. The cross sections can be determined by detecting the charged particles produced, or in some cases via the de-excitation y rays from the populated excited states.