QUASI-ELASTIC KNOCKOUT REACTION 28SI(ALPHA,2ALPHA)24MG

The α-cluster knockout reaction 28Si(α, 2α)24Mg is investigated at an incident energy of 104 MeV. In a coplanar, symmetric geometry the energy distribution spectra of the coincident a-particles are measured at seven pairs of angles between 28°, 28° and 41.5°, 41.5° (quasi-elastic angles). It is shown that besides the ground state of the recoil nucleus 24Mg also the lowest excited states are found. There are, therefore, different α-cluster parent states that contribute to the wave function of a 28Si. The most probable configuration that is found in our experiment is the coupling of a 24Mg core in the excited level with l = 4 (Eexc = 4.12 MeV) with a probability of about 10%. © 1969.