Absorption and backscatter of internal conversion electrons in the measurements of surface contamination of 137Cs

We measured 4 pi and 2 pi counting efficiencies for internal conversion electrons (ICEs), gross beta-particles and also beta-rays alone with various source conditions regarding absorber and backing foil thickness using e-X coincidence technique. Dominant differences regarding the penetration, attenuation and backscattering properties among ICEs and beta-rays were revealed. Although the abundance of internal conversion electrons of Cs-137-Ba-137 is only 9.35%, 60% of gross counts may be attributed to ICEs in worse source conditions. This information will be useful for radionuclide metrology and for surface contamination monitoring. (C) 2013 Elsevier Ltd. All rights reserved.