Sub-micron wear measurement using activities under the free handling limit

In the present work we demonstrate the development of a thin layer activation (TLA) method to be able to measure micrometer wear or less by using radioactive tracing. In order to activate very swallow depths we decreased the bombarding energy to the "linear" region of the cross-section curve. The disadvantage of the method is that the wear curve will be "linear" near to the surface instead of "constant" as is the case with the usual (high energy) TLA. The advantage is that the activity of the sample will be much lower and it is concentrated in the swallower studied depth. The other possible method is irradiation under small angle (15 to 30 degrees or even grazing incidence), which also causes a near-surface concentration of the activity produced. Both methods are demonstrated with the most suitable nuclear reactions and some commonly used industrial materials.