Household salt for retrospective dose assessments using OSL: signal integrity and its dependence on containment, sample collection, and signal readout

Abstract

The aim of this work was to determine how a latent optically stimulated luminescence (OSL) signal in irradiated household salt is preserved under various ambient conditions, from the time of exposure to the time of signal readout. The following parameters were examined: optical fading in fluorescent light and under darkroom conditions (red light), thermal stability of the OSL signal during storage in a light-tight container, optical fading in representative container types, and sensitization effects of the OSL signal in exposed household salt. Furthermore, the influence of grain mixing within the saltshaker or salt container was studied by determining the dose gradient within typical salt packages. Finally, the signal integrity of salt irradiated under field conditions in a village in Belarus contaminated by Chernobyl fallout was investigated. The results show that the OSL signal in household salt is preserved in large cardboard box containers, but not in white plastic salt containers or in small portion bags used in, e.g., fast food restaurants. Furthermore, the continuous wave blue OSL signal in household salt does not fade significantly during storage up to 140 days. On the contrary, the signal appears to slowly increase during storage ("inverse fading"). Field tests of two different salt containers (with and without black tape to block light) located in Belarussian households confirmed that the signal is preserved in white plastic salt containers when they are covered with extra light-shielding material.

NaCl pellets for prospective dosimetry using optically stimulated luminescence: Signal integrity and long-term versus short-term exposure

“…The same trend was obtained and discussed in previous work (Waldner and Bernhardsson 2018 ). Others have also observed indications of inverse fading of the OSL signal, both for a short time scale of seconds (Biernacka et al 2016 ) and a longer time scale of days (Christiansson et al 2014 ). However, those observations were related to a different phenomenon than the one observed here.…”

Comparative measurements of external radiation exposure using mobile phones, dental ceramic, household salt and conventional personal dosemeters

“…While casing of mobile phones provides sufficient light protection, ensuring these conditions can be problematic for other materials in practice. In the case of a real radiological event, only salt in light-tight packaging can be used (Christiansson et al, 2014). If a sample of dental ceramic was taken from an irradiated person, only a TLD measurement would be usable because the TL signal corresponding to a peak at z280 C is relatively light resistant (Ekendahl et al, 2013).…”

Uncertainty on Radiation Doses Estimated by Biological and Retrospective Physical Methods

“…As an example, in case of human teeth as well as integrated circuits from mobile phones, the fading curves were better fitted by a bi-exponential decay function 100,102 . In contrast to electronic components, sensitive dosemeter materials with comparatively slow or no fading, such as household salt (NaCl) 101,105 and quartz extracted from building materials [106][107][108] . The application of retrospective luminescence dosimetry in areas affected by fallout from the Semipalatinsk nuclear test site: an evaluation of potential.…”

“…The detection limit in such materials is related to the magnitude and the uncertainty in the background signal. The background absorbed dose in for example household salt may vary depending on how the salt was manufactured 101 , in what package it was kept, and how and where this package was stored 105 . For quartz extracted from bricks, the background dose depends on the concentration of natural radionuclides in brick, plaster and soil in front of the building and on the age of the bricks (same references as above).…”