Reactions induced by proton bombardment of aluminium

Abstract

The excitation functions of the reactions ²⁷Al(p, p₀)²⁷Al,²⁷Al(p, p₃)²⁷Al^∗ and ²⁷Al(p, α₀)²⁴Mg are measured in the proton energy range E_p = 3.5 - 5.5 MeV with an energy resolution of about 5 keV. The differential cross sections are measured with an accuracy of ±15% at lab angles of 90° and 150°. The excitation curves exhibit sharp maxima of 10 to 50 keV width superimposed on a broad 150-200 keV wide structure. A fluctuation analysis of the data in terms of autocorrelations yields a coherence energy varying from 15±3 keV to 22±3 keV depending upon the excitation functions and the averaging interval chosen. Non-zero cross correlations between the two α₀ yield curves and the p₃ yield curve indicate the presence of the correlated resonance structure due to individual or groups of similar levels in the compound nucleus ²⁸Si in the region of excitation from 15.3 to 16.9 MeV.