Precise measurement of the differential cross section from the¹⁶O(α,α)¹⁶O elastic reaction at 165° and 170° between 2.4 and 6.0 MeV

Non-Rutherford cross section for elastic scattering of α particles from oxygen has been measured for energies between 2.4 and 6.0 MeV at commonly used backscattering angles of 165° and 170°. High precision in energy has been obtained with a 2 MV 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 20Ne have been deduced. The well-known resonance E_R=3031.7±0.5 keV and the narrow and intense resonance E_R=5375.5±0.5 keV, 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.