Analysis of 238U, 232Th, 222Rn and 220Rn contents in medical drugs, petroleum products and petrol/gas-oil exhaust fumes by using CR-39 and LR-115 type II nuclear track detectors – Experimental and new Monte Carlo simulation approaches

Abstract

Petroleum products and medical drugs have been studied in order to determine 238U, 232Th, 222Rn, 220Rn and their progenies contents in them using mean absolute detection efficiency based Solid State Nuclear Track Detectors (SSNTDs) experimental method. In the present paper, a Monte Carlo code based theoretical approach has been also developed to determine mean absolute detection efficiencies of SSNTDs; this theoretical approach has been combined with experimental one for deriving levels of natural radioactivity inside different materials studied. The dependence of CR-39 and LR-115 type II mean absolute detection efficiencies on initial alpha particle energy, removed thickness of SSNTDs and SSNTDs areas for different natural materials studied has been highlighted as well. The mean absolute detection efficiency depends clearly on the initial alpha particle energy and the removed layer while it does depend neither on the detector surface nor on the nature of the material being studied. The results obtained using the present method and those obtained by mean critical angle based SSNTD technique and isotope dilution mass spectroscopy (IDMS) are in good agreement with each other: our method has less relative uncertainties, which do not exceed 4%, than the other methods, whose the relative uncertainties exceed 9% and 7%, respectively.