Photon radiation dose enhancement at material interfaces

Experimental radiation dose-effect studies at a material's interface requir e high-resolution dose measurements resulting from the exposure of mounted samples on a supporting substrate. Reflections of photons and electrons fro m the substrate increase the effective dose to the sample relative to dose from the direct beam incident on the unbacked sample. This difficult-to-mea sure enhancement of effective dose can be calculated easily with Monte Carl o transport codes. We have used the Monte Carlo code, CYLTRAN, to carry out radiation transport and dose calculations in very thin water layers backed by different substrate materials. We present cases with an incident photon beam (15 - 100 keV) on a water medium with five different substrates - myl ar, aluminum, copper, silver, and gold. Published by Elsevier Science Ltd.