Stopping power measurement using surface barrier detectors and thick alpha sources

The alpha energy spectrum emerging out of a plane surface of an infinitely thick medium, in which alpha emitters are distributed uniformly, is inversely proportional to the stopping power of the medium. Applying this principle, the stopping power of a substance which is not available as a thin foil or in gaseous form can be obtained for a wide energy range in a single measurement. The stopping power of water for alpha particles with natural uranium alphas and the stopping power of Li-halogenide for alphas and tritons through 6Li(n, α)T reaction were obtained from the energy spectra measured by Si surface barrier detectors in contact with the media. (orig.)