Neutrons, radon, nanoparticles, and nanoholes: Everything comes to a full circle with track detectors

Abstract The first passive radon monitor was termed radon film-badge, in analogy with the neutron film-badge. This monitor, instead of a radon film-badge, should be considered the first diffusion chamber, the principle of which has been exploited in all existing passive radon-monitors. In the present paper, a true radon film-badge is proposed, which is formed by a thin-film radiator with suitable radon-sorption characteristics, facing a track detector. At the nanometer scale, the sorption in these radiators occurs by trapping the nanometers particles, formed by the radon atoms, into the nanoholes of technological advanced materials. When compared with existing passive radon-monitors, these radon film-badges present several advantages, such as a wide linearity of response, any desired response sensitivity, a unique simplicity in measuring radon in soil and in water. Radon-decay-products attach to airborne particles and thus acquire a wide range of sizes both in nanometer and micrometer scales. By employing a strategy similar to that used for neutrons, a very compact badge has been recently proposed, which shows promise for the solution of the complex problem of the radon-decay product dosimetry.