New Method for Measuring the α -Particle Range and Straggling in Liquids

The ranges of Po α particles in water and five other liquids have been measured with a new method involving a steel surface as support for the α source and a CaWO₄ crystal surface as detector for the α particles. The surfaces are optically plane and parallel and constitute the walls of a microcell for the liquid. The range obtained at 25^∘{}C in water was 39.9 microns, 2.7 percent longer than the value 38.8 microns, computed with the Bragg law from range measurements in gaseous hydrogen and oxygen. In the other five liquids the ranges obtained also were longer (2.3-4.6 percent) than the correspondingly computed Bragg law values.