A probe for detecting K-alpha photon emissions. A housing has an aperture at an end. A detector crystal is situated within the housing adjacent to the housing aperture. An energy conversion device is situated within the housing between the detector crystal and the aperture. The energy conversion device is made from a predetermined material configured to convert energy directed through the housing aperture from a source of primary photon emission radiation to a corresponding secondary K-alpha emission within a predetermined emission energy acceptance window. A power supply is coupled to the detector crystal and is configured to establish a polarized electrical field between the anode and the cathode of the detector crystal. The detector crystal receives the K-alpha emission and generates an electrical signal representative of the amount of target emissions received through the housing aperture.