Development of an economic prototype to monitor radon in industrial facilities and housing

The ²²²Rn is formed by the disintegration of ²²⁶Ra, then it disintegrated in ²¹⁸Po and ²¹⁴Po. The produced Po ions were electrostatically collected using a polarized chamber connected to a high tension power supply, then the ²¹⁸Po decay to ²¹⁴Pb emitting α particles of 6.003 keV and later the ²¹⁴Po decay to ²¹⁰Pb emitting α particles of 7.687 keV. When the concentration of the α particles is measured in the chamber, it is possible to indirectly determine the radon concentration in the air. The prototype was developed using a 2 L stainless steel chamber and a bare PIN diode S3204-09 (Hamamatsu) as an alpha particles detector. The chamber and diode were polarized with a HV power supply (+500 V) to collect Po ions and detect the alpha particles that are produced during the decay process.The operation and digital functions were implemented in a PIC18F4550 microcontroller and this device has an internal USB communication module to transfer data to a PC. The configuration of the operation basic parameters is done by a laptop using the USB port. The system was calibrated using an Alfaguard ® commercial equipment, applied to an area where uranium was buried, in order to have a radon source; the measurements were done in different points with different radon concentrations. The radon concentration in close and ventilated offices was monitored and was observed how the radon concentration varies during several days. (authors)