Barrier‐Type anodic films on aluminium in aqueous borate solutions: 1—Film density and stopping power of anodic alumina films for alpha particles

Stopping powers of an anodic film, formed on aluminium in aqueous ammonium pentaborate solution, have been measured experimentally for α particles, over the energy range 0.7–2.3 MeV. Comparison between the measured stopping powers and theoretically calculated values shows that Bragg's Rule may be applied, with reasonable accuracy (∼5%), to predict the stopping powers of anodic alumina. The density of the barrier‐type film was determined by Rutherford backscattering spectroscopy to be 3.10±0.15 × 10 3 kg m −3 .