Calibration of a low background gas-flow proportional counter to estimate 234Th activity in coastal waters

E Cuesta; R L Lozano; E G San Miguel; M Casas-Ruiz; J P Bolívar

doi:10.1016/j.apradiso.2016.09.016

Calibration of a low background gas-flow proportional counter to estimate ²³⁴Th activity in coastal waters

Appl Radiat Isot. 2016 Dec:118:201-210. doi: 10.1016/j.apradiso.2016.09.016. Epub 2016 Sep 13.

Authors

E Cuesta¹, R L Lozano¹, E G San Miguel², M Casas-Ruiz³, J P Bolívar¹

Affiliations

¹ Departamento de Fisica Aplicada, Universidad de Huelva, Campus de Excelencia Internacional del Mar (CEIMAR), 21071 Huelva, Spain.
² Departamento de Fisica Aplicada, Universidad de Huelva, Campus de Excelencia Internacional del Mar (CEIMAR), 21071 Huelva, Spain. Electronic address: sanmigue@uhu.es.
³ Departamento de Fisica Aplicada, Universidad de Cádiz, Spain.

PMID: 27657460
DOI: 10.1016/j.apradiso.2016.09.016

Abstract

This paper relates the calibration of a low background gas-flow proportional counter. This calibration has been used to determine low activity of ²³⁴Th in coastal water samples. Two methods were used to prepare calibration samples: Evaporation and Electrodeposition. First method was rejected due to the lack of reproducibility because the different geometry adopted by the drops of tracer once dried on the disk. On the contrary, through the second method, similar efficiencies were obtained in all detectors with an average of 0.401±0.004. In this paper, the whole procedure to obtain ²³⁴Th activity in dissolution as well as in particulate matter has been detailed, and all the algorithms needed to calculate activities and efficiencies are shown. Finally, two experiments have been designed in order to validate the calibration of the beta counter and the method to determine ²³⁴Th in coastal waters with high concentration of particulate matter.

Keywords: Beta counting; Calibration; Methodology; Thorium-234.