Radon alpha track counting on solid state nuclear track detector by an ImageJ-based software macro.

Radon (222Rn) is a radioactive gas emanating from geological materials. Inhalation of this gas is closely related to an increase in the probability of lung cancer if the levels are high. The usual methodology for the quantification of radon by passive methods is the use of etched solid-state nuclear track detectors, frequently in combination with optical microscopes or image scanning for image acquisition and software-based image processing for track counting. Currently available commercial instrumentation, as the Radosys microscopy system, is quite expensive, so the development of alternative methodologies is desirable. In this work, a simple, fast and low-cost image acquisition system for the determination of tracks in chemically etched CR-39 solid-state nuclear track detectors to quantify 222Rn alpha tracks has been proposed. The image of the detector surface is obtained by a conventional light stereoscopic microscope, transmitted by a CCD camera into the computer, and analyzed by the ImageJ open-source software. This methodology was employed to analyze 45 samples collected in dwellings and caves located in the region of Extremadura (Southwest Spain). Results show a good correlation coefficient of r2 = 0.98 between the reference and purposed methodology and excellent repeatability, demonstrating that the system enables routine counting tracks for radon measurement as an alternative to the Radosys microscopy instrument.

Influence of source composition and particle energy on the determination of gross alpha activity.

The influence of different source compositions and α-particle energies on the detection efficiency of a gas-flow proportional counter was examined using experimental measurements and Monte Carlo simulations. Efficiency variation with alpha-particle energy was very marked, being less significant with the substrate composition. These results show that the determination of gross alpha activity in an unknown sample must be carried out very carefully in order to give a correct estimation of its activity.

Radon in workplaces in Extremadura (Spain).

Indoor radon measurements are usually associated with housing. However, a typical person spends about one-third of the day at their workplace. A survey was made of radon levels in workplaces in Extremadura (Spain). More than 200 measurements were performed in some 130 firms and organizations of different sectors (urban wellness centres, spas, caves, mines, water management facilities, underground carparks, wine cellars, museums, etc.). Activated charcoal canisters and track detectors were used for sampling. The results indicated the importance of performing this type of measurement because the exposure of workers can reach high values in some cases.