Present knowledgement of ~3He(~3He,2p)~4He and ~3He(~4He,γ)~7Be

摘要

New direct experimental methods and techniques, combined with the development of new theoretical tools have opened new avenues to explore nuclear reactions of significance for nucleosynthesis at or near the actual temperatures of stellar burning. The main difficulty of direct measurements is determined by the background, which, together with the low cross sections, set a limit on the energy range that can be investigated with a simple setup on the earth's surface. Essentially there are three sources of background, cosmic rays, environmental radioactivity and beam-target induced nuclear reactions. Each of these sources produces background of a different nature and energy, so that each reaction studied needs special care to suppress the relevant background component. We will show two different experimental approaches that have been used to study processes of astrophysical interest. In particular, we will focus our attention on underground experiments and the recoil mass separator approach used to measure ~3He(~3He,2p)~4He and ~3He(~4He,γ)~7Be.