Study of gamma backscattering in soil layers with different thickness and water content
J. Gómez-Muñoz 1*, M. L. Cortés 1,2, F. Cristancho 1,2
1 Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia.
2 Centro Internacional de Física, Bogotá, Colombia.
Backscattering of gamma rays has been used to study soil properties such as porosity, hydraulic conductivity and also for the detection of objects buried in soil. These applications require the understanding of the interaction of gamma rays with soil. In this work a study of the interaction of 511 keV gamma rays with layers of soil, varying its thickness and water content, is presented. The experimental setup uses the positron decay of a radioactive 22Na source and two gamma detectors connected in fast time-coincidences. Backscattering spectra were obtained and the number of single and multiple backscattering photons as a function of thickness was analyzed. The results are compared with those previously obtained for the sand and its corresponding theoretical model .
 M. L. Cortés et al., AIP Conf. Proc. 1265 (2010), 395.