Development and calibration of a method for direct measurement of 220 Rn (thoron) activity concentration.

Autor: Ambrosino F; Centre for Isotopic Research on Cultural and Environmental Heritage (CIRCE), Department of Mathematics and Physics, University of Campania 'Luigi Vanvitelli', Viale Lincoln 5, 81100, Caserta, Italy; National Institute for Nuclear Physics (INFN), Branch of Naples, via Cinthia 21, 80126, Napoli, Italy. Electronic address: fabrizio.ambrosino@unicampania.it., Roca V; National Institute for Nuclear Physics (INFN), Branch of Naples, via Cinthia 21, 80126, Napoli, Italy., Buompane R; Centre for Isotopic Research on Cultural and Environmental Heritage (CIRCE), Department of Mathematics and Physics, University of Campania 'Luigi Vanvitelli', Viale Lincoln 5, 81100, Caserta, Italy; National Institute for Nuclear Physics (INFN), Branch of Naples, via Cinthia 21, 80126, Napoli, Italy., Sabbarese C; Centre for Isotopic Research on Cultural and Environmental Heritage (CIRCE), Department of Mathematics and Physics, University of Campania 'Luigi Vanvitelli', Viale Lincoln 5, 81100, Caserta, Italy; National Institute for Nuclear Physics (INFN), Branch of Naples, via Cinthia 21, 80126, Napoli, Italy.
Jazyk: angličtina
Zdroj: Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine [Appl Radiat Isot] 2020 Dec; Vol. 166, pp. 109310. Date of Electronic Publication: 2020 Jul 05.
DOI: 10.1016/j.apradiso.2020.109310
Abstrakt: The interest in the measurement of thoron ( 220 Rn) activity concentration in air has recently increased, with the attention for the development of standards useful for the calibration of measuring instruments. Due to its short half-life (55.8 s), consolidated techniques for the realization and the use of controlled atmospheres of radon ( 222 Rn) are not effective in the case of thoron. New adequate methodology are required. A method for the measurement of the thoron reference activity based on the direct detection of the alpha particles produced by the decay of 220 Rn, from natural samples containing 232 Th, is here proposed. The possibility of observing an acceptable spectrum is entrusted to the realization of measurement chambers small enough to reduce as much as possible the energy loss of the alpha particles before they reach the Silicon detector. Such a chamber was realized and used with a known thoron atmosphere in a controlled environment. The experimental results are compared with those obtained from the simulation with the Monte Carlo method: (i) the alpha spectra coming directly from thoron atoms exhibit similar shape with a linear trend plus an exponential trend on the left side of the 220 Rn peak, depending from the distance between source and detector; (ii) the corresponding 220 Rn detection efficiency values are compatible considering the uncertainties. An investigation was conducted to study the shape of the 220 Rn spectra vs the different volume of chambers, through Monte Carlo simulations. The results show: (i) the linear part of the spectra shape goes to reduce with the increasing of the height of the chamber; (ii) the 220 Rn detection efficiency decreases with the increasing of the height of the chamber.
(Copyright © 2020 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
Externí odkaz: