Theoretical evaluation of calibration factor for LR-115 cellulose nitrate solid state nuclear track detectors: A model for determining alpha radioactivity level in natural water

Abstract

Alpha-sensitive solid-state nuclear track detectors (SSNTDs) are used successively for decades for determining the alpha-radiation level in various environmental materials. A model for measurement of total alpha-radioactivity in natural water by using alpha-sensitive LR-115 type II cellulose nitrate (CN) film SSNTDs has been developed in the present work. The LR-115 CN films in bare mode are assumed to be immersed into a water sample for alpha-exposure. During the exposure time period, the alpha-particles that are emitted from the alpha-emitters present in the water sample will interact with the CN film and create their latent trails in the film. These latent trails will be manifested as pits of alpha-tracks after chemical etching of the exposed film. For alpha-radioactivity measurement, calibration factor (CF) for LR-115 type II SSNTDs has been evaluated theoretically by using the range of alpha-particles of residual energies situated between 1.6 MeV and 4.7 MeV in natural water and the actual geometry of experimental setup for alpha-exposure. The evaluated CF is found to be 204.93 Bq.l − 1.(tracks. cm − 2.h − 1)−1. The evaluated CF and experimental procedure can reliably be utilized in monitoring the alpha-radioactivity of natural water and in other radioactivity field measurements.