Latest developments in silica-based thermoluminescence spectrometry and dosimetry

Abstract

Using irradiated doped-silica preforms from which fibres for thermoluminescence dosimetry applications can be fabricated we have carried out a range of luminescence studies, the TL yield of the fibre systems offering many advantages over conventional passive dosimetry types. In this paper we investigate such media, showing emission spectra for irradiated preforms and the TL response of glass beads following irradiation to an Am-Be neutron source located in a tank of water, the glass fibres and beads offering the advantage of being able to be placed directly into liquid. The outcomes from these and other lines of research are intended to inform development of doped silica radiation dosimeters of versatile utility, extending from environmental evaluations through to clinical and industrial applications.

Characterisation of an isotopic neutron source: A comparison of conventional neutron detectors and micro-silica glass bead thermoluminescent detectors

“…Prior to installation of the AmBe source used in this investigation (Eckert and Ziegler, 2007) a similar measurement was performed with a slightly different configuration (Bradley et al, 2016) and was identical to that studied by (Taggart, 2007;Nicolaou, 1983;Matthews, 1979) with two AmBe sources ∼20 cm apart. Therefore, in these previous studies, it is important to consider that there will be independent contributions from each separate source.…”

“…Therefore, in these previous studies, it is important to consider that there will be independent contributions from each separate source. The spikes were less likely to be observed either due to lower spatial resolution (Taggart, 2007;Nicolaou, 1983;Matthews, 1979) or the possibility of the effect of combining contributions from two sources in the water tank (Bradley et al, 2016).…”

“…A simulation was developed using the general Monte Carlo N-Particle transport code, MCNPX (Hendricks et al, 2008) modelling the passage of neutrons through the pure water shield. It was previously discussed in (Bradley et al, 2016) and is based on a preliminary mathematical model representing the physical neutron tank used to expose the beads. Several assumptions were made about the AmBe source including a neutron energy spectrum from Amersham source calibration data and an internal source construction based on an americium-beryllium layered structure.…”

“…Work thus far has concerned the effectiveness of glass bead dosimeters for use with the latest radiotherapy developments (Teoh et al, 2011;Chang and Timmerman, 2007) and specifically that the dimensions of the dosimeter should be small with respect to the radiation field dimensions (Jafari et al, 2014a;Bjarngard et al, 1990;Higgins et al, 1995;Fracescon et al, 1998;Sauer and Wilbert, 2007;Aspradakis et al, 2010) whereas the focus of the most recent studies have been the introduction of a mixed radiation field as described in (Bradley et al, 2016) and here. The relevance of this point is that the response of the glass bead cannot be solely due to neutron interactions (capture, scattering, or gamma production) and that a significant gamma factor will contribute to the thermoluminescent yield whereas the γ efficiency is very low for the comparative gas detectors (Kouzes et al, 2009;Reilly et al, 1991).…”

Characterisation of borosilicate glass media as potential thermoluminescent dosimeters

“…The TL signal shows peaks at temperatures that are associated with release from the electron-hole traps. Of note is that the many emergent TLcharacteristics of non-conductive amorphous media, all familiar in use of crystalline media, can also find effective interpretation through adoption of the energy band model (Bradley et al, 2015(Bradley et al, , 2016. For effective TL dosimetry important features include high sensitivity, linear response for a wide dose range, stability and a simple glow curve (Laboratory Resource, 2019).…”