Structure in the ²⁷Al(p, α)²⁴Mg cross section between E_p = 4.0 and 5.5 MeV

Abstract

The excitation functions of the reactions ²⁷Al(p, α₀)²⁴Mg and ²⁷Al(p, α₁)²⁴Mg^∗ were measured in the proton energy range E_p = 4.0-5.5 MeV with an energy resolution of about 5 keV at lab angles of 60°, 90° and 165°. The excitation curves exhibit sharp maxima of widths between 10 and 50 keV superimposed on a broad 150-300 keV wide structure. The channel as well as angle cross correlation functions calculated with moving averages are high for all the cases. This as well as strong visual correlations of the sharp and the broad structure between various curves lead to the conclusion that the observed structure, both fine as well broad, is due to individual resonance effects and not to fluctuations. It is suggested that the fine structure is due to very slightly overlapping compound nuclear levels, while the broad structure may represent the "intermediate states" of the compound system.