Gamma-ray measurements of naturally occurring radioactive samples from Cyprus characteristic geological rocks

TL;DR

This study used gamma-ray spectroscopy to measure natural radioactivity in various geological rocks in Cyprus, providing data on activity concentrations, elemental levels, and radiation dose estimates for different rock types.

Contribution

It offers comprehensive gamma-ray measurements across Cyprus's geological formations, filling data gaps on natural radioactivity in the region.

Findings

Activity concentrations of Th-232, U-238, and K-40 vary across rock types.

Calculated outdoor dose rates range from 0.1 to 50 nGy/h.

Estimated effective dose rates per person are up to 61.4 microSv/y.

Abstract

Using high-resolution gamma-ray spectroscopy, the terrestrial gamma radiation in all the predominant types of geological rock formations appearing in Cyprus was measured. Soil samples were collected from each rock type, sealed in 1-litre plastic Marinelli beakers, and measured in the laboratory for 24 hours each. From the measured gamma-ray spectra, activity concentrations were determined for Th-232 (range from 1.3 to 52.8 Bq/kg), U-238 (from 0.9 to 90.3 Bq/kg) and K-40 (from 13 to 894 Bq/kg). Elemental concentrations mean values of (2.8 +- 0.7) ppm, (1.3 +- 0.3) ppm and (0.6 +- 0.1) % were extracted, for thorium, uranium and potassium, respectively. Absorbed dose rates in air outdoors were calculated to be in the range of 0.1-50 nGy/h, depending on the geological features, with an overall mean value of (14.7 +- 7.3) nGy/h. The corresponding effective dose rates per person outdoors were estimated to be between 0.1 and 61.4 microSv/y, assuming a 20% occupancy factor.