The (α, p) reaction on 40, 42, 44, 48Ca and 48Ti at 31 MeV

Abstract

The (α, p) reaction has been observed on 40, 42, 44, 48 Ca and 48 Ti with 150 keV resolution at an incident energy of 31 MeV. From the negligible excitation of d 3 2 hole states and from the angular distributions and relative cross sections for ground state transitions in the 1 f 7 2 shell, the reaction mechanism is shown to be stripping. A gap of approximately 2.5 to 3 MeV in the proton spectra was observed to occur for nuclei towards the end of the 1 f 7 2 shell ( 47 Sc and 51 V) and is given a qualitative explanation. This gap ends with the onset of p 3 2 strength. Strong J -dependence is observed and enables us to distinguish between p 3 2 and p 1 2 transitions. This J -dependence is calculable by the distorted wave Born approximation (DWBA). Three L = 5 transitions were observed. These high-spin states have not been previously identified. The systematic behaviour for transitions of each L and the good agreement with zero-range DWBA calculations based on a three-nucleon transfer mechanism enable one to make spin assignments. This was particularly valuable in the case of 51Sc which is difficult to reach by other reactions.