Measurement of the surface mass of a heavy element thin target in the presence of light elements

Elastic scattering of α particles has been used to measure the quantity of a heavy element of given Z (>= 28) in a target the other components of which are light (Z < approximately 17). The α particles are emitted by 212Po from a radioactive emanation source. Calibrations of the device can be made using a target of known thickness of any other heavy element. A precision of the order of +- 10% can be reached. (Auth.)