Simulation of alpha particle emitted by 222Rn from natural spring water in Puebla, México.

A computational simulation of alpha-particle expansion, emitted by 222Rn naturally diluted in the water of a spring located in the state of Puebla Mexico, is presented. This simulation provided information on the volume of expansion of the alpha particles in the vicinity of the spring and thus awareness if there was a radiological risk for the users or the population that lived near to it. Before performing the simulation, several measurements were made to water samples with a dynamic measurement system. This in order to know the level of radon concentration and compare the results obtained with the levels recommended by the United States Environmental Protection Agency (US-EPA) and the World Health Organization (WHO). In addition, to know if there was a radiological risk due to the presence of gamma emitting radionuclides, complementary water analyses were carried out using gamma-ray spectrometry techniques. The simulation was developed using the scientific software of particle interaction with matter, Geant4. The different variables declared for the software parameters are presented in this document. The results of the radon measurements in the water and the computational simulation, determined that there was no radiological risk due to alpha radiation. Furthermore, the results from the gamma-ray spectrometer showed that there was no presence of other hazardous radionuclides in the water.

PbS nanostructured thin films by in situ Cu-doping.

PbS:Cu nanocrystalline films were prepared by chemical bath at temperature of 80 degrees C and deposited on glass substrates. Different Cu-doping levels were obtained changing the volume of the Cu-reagent-solution into the PbS growing solution. X-ray diffraction (XRD) and optical absorption (OA) measurements were carried out to characterize the semiconductor. The morphological changes of the layers were analyzed using an atomic force microscopy. Diffraction X-ray spectra displayed peaks at 2 theta = (26.00, 30.07, 43.10, 51.00 and 53.48), indicating growth on the zinc blende face. The grain size determined by X-rays diffraction of the undoped samples, was found -37 nm, whereas with the doped sample was - 32-25 nm. Raman spectra reports strong band in - 133-140 cm(-1) attributed to a combination of longitudinal and transversal acoustic modes. Optical absorption, forbidden band gap energy (E(g)) shift disclose a shift in the range 1.4-2.4 eV. Gibbs free energy calculation for the Cu doping PbS is also included heading.