at least two electrode plates orientated parallel to each other defining a set of electrode plates wherein for each set of electrode plates a first plate is a cathode comprising a material possessing an element with an atomic number≧26, and wherein a second plate is an anode; and

a dielectric material interposed between the at least two electrode plates wherein absorption of ionizing radiation of a particular energy range by at least one of the at least two electrode plates produces secondary ionization in the dielectric material resulting in radiation induced conductivity of the dielectric material creating a measurable electric current when an external voltage is imposed between the anode and the cathode.