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Dechanneling of positrons due to lattice disorder has been investigated for two stable configurations of the disordered face-centered cubic(fcc) lattices, Dumb-bell configuration (DBC) and Body-centered interstitial (BCI) for channeled positrons with incident energy (10–200) MeV in Cu single crystal in the planar direction (100). The effects of anharmonic terms in the channeling potential have been considered in the calculations. The calculations covered the transition-channeling probability, dechanneling probability, transmission and dechanneling coefficients. It has been found that the transition-channeling probability from the normal into the disordered region occurs only for the transitions n (normal) → n (disordered). Also the dependence of the transmission and dechanneling coefficients on the incident beam position has been studied by using a planar potential function based on shell structure model and compared with the results of a planar potential based on Lindhard's model.

Geological materials usually contaminated with naturally occurring radioactive materials (NORM) have become a focus of great attention. The gamma radiation in samples of a variety of natural tiling rocks (granites) collected from different factories in Egypt for use in the building industry was measured, employing high-resolution g-ray spectrometry. In order to assess the radiological impact from the granites investigated. The radiological hazard indices, annual effective dose equivalent (outdoor and indoor) (Deff), hazard indices (Hex and Hin), activity utilization indices (Ig, Ia) and excess life time cancer risk (ELCR) were calculated. The radiological hazard indices for most granite samples are higher than the internationally recommended values.

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