Precise measurement of the differential cross section from the O16(α,α)O16 elastic reaction at 165° and 170° between 2.4 and 6.0MeV

Non-Rutherford cross section for elastic scattering of α particles from oxygen has been measured for energies between 2.4 and 6.0MeV at commonly used backscattering angles of 165° and 170°. High precision in energy has been obtained with a 2MV Tandetron accelerator, with precise and stable energy calibration. The choice of a thin Ta2O5∕Ta∕C standard increased the sensitivity and reduced systematic errors due to the geometry. Precise data for energy, width, and ratio to Rutherford of the resonances have been extracted from nuclear shell models, and excitation levels of Ne20 have been deduced. The well-known resonance ER=3031.7±0.5keV and the narrow and intense resonance ER=5375.5±0.5keV, not included in cross-section libraries, have been applied for surface oxygen analysis in thin WCN∕SiO2∕Si multilayer samples, with improved depth resolution by optimizing the measuring geometry.