Application of UV-Visible spectroscopy for measurement of Track density in LR-115 SSNTD based DTPS/DRPS

As measurement of inhalation dose due to radon and thoron progeny is very important in indoor as well as occupational environments, the solid state nuclear track (LR-115) based passive progeny sensors such as Direct Radon Progeny Sensor (DRPS) and Direct Thoron Progeny Sensor (DTPS) are extensively used for this purpose. These detectors need to be chemically etched and spark counted for estimation of track density which is then converted into progeny concentration and finally into inhalation dose using appropriate calibration factors. But for high exposure situations, these detectors have limitations and leads to underestimation of dose. In the present study, we have investigated the possibility of using UV-Visible spectroscopy as an alternative way to estimate the track density in these detectors which can be converted into corresponding progeny concentrations and ultimately to inhalation dose. The transmission spectrum of these progeny sensors under UV-Visible spectrophotometer shows a characteristic peak about wavelength of 380 nm and the variation in transmission at this wavelength was analyzed against the varying alpha exposure. The variation of transmission at 380 nm was observed to be linear with respect to the track density and these linear relations could be used for estimating track density for unknown exposure. This method is a non-destructive alternative way of measuring track density in the DTPS and DRPS and it will be useful for high exposure conditions.