Abstract: A method and apparatus for detecting mostly-plastic mines having steel firing pins and copper igniter cups. A frequency spectrum is transmitted, and response signals from the metal components induced by resultant eddy currents are detected. The firing pin generates a response characterized by a first frequency that is in phase with the transmitted frequency, whereas the igniter cup generates a response characterized by a second frequency that is in quadrature with the transmitted frequency. Accordingly, the detected response can be compared to prestored response templates to determine what type of mine, if any, has been detected, with the use of two response frequencies and phase relationships enabling the discrimination of buried plastic mines from surrounding metal particles in the earth.

Abstract: Apparatus for use in alpha particle counting with such as photomultiplier tubes, comprising a platform and linkage mechanism whereby samples are moved in linear manner toward and away from ends of the photomultiplier tubes.