(p, α) reactions to N = 28 nuclei at bombarding energies between 11 MeV and 12.5 MeV

Abstract (p, α) reactions leading to the N = 28 nuclei V 51 , Mn 53 , Co 55 and Cr 52 have been observed at incident proton energies between 11 MeV and 12.5 MeV. The α spectra were detected by solid-state counters with energy resolutions of ≈ 50 keV. New information on the level structure of Mn 53 , Co 55 and Cr 52 was obtained. Excitation functions and angular distributions were measured with an energy spread in the beam of less than ±2 keV. On the basis of these data the possible mechanisms of the observed (p, α) reactions are discussed and it is concluded that compound-nucleus formation plays a major role. The nuclear level schemes are compared to the theoretical calculations of Kisslinger and Sorensen and of de-Shalit.