A new passive integrating detector for measurement of individual radon exposure at working places

A new instrument was developed to measure radon exposure with the use of passive monitors like nuclear track etch detectors. It is based on a device to be switched on and off to permit accurate measurements of timed exposures. The detector arrangement consists of a small cylindrical chamber, a mobile piston inside, a filter holder, a detector holder. The internal sampling volume is variable. The piston is air-tight to fulfill the pumping function: when pull the piston air is driven inside through the filter, and when push the piston all the radon laden air is driven out. The piston can reduce the volume of air adjacent to the track detector to near zero to avoid track detector exposure during storage and shipment. The new dosimeter distinguishes itself from others by the fact that the exposure monitoring begins when the piston device is opened and stops when it is closed. Different prototypes have been realized and tested. The unique characteristics of new ENEA radon dosimeter allow optimizing calibration procedures. Experimental facilities have been realized which allow starting detector exposure only at stationary conditions to avoid effects of varying radon concentration during exposure of passive integrating detectors. An outstanding application of this new technique concerns monitoring radon exposure at work places. Personal dosimeters can be worn to measure the radiation exposure of a person at different working areas and can be used to document an exposure. Sequential exposures can be monitored to correlate the presence of workers with radon exposure during working shifts. The aim of the paper is to briefly describe the main characteristics of this novel technique and the results of experimental performances of different prototypes.