Observations on the thermoluminescence signal induced by
alpha radiation
D. Vandenberghe
a,
*, F. De Corte
a
, P. Van den haute
b
a
Laboratory of Analytical Chemistry, Institute for Nuclear Sciences, Proeftuinstraat 86, B-9000 Gent, Belgium
b
Laboratory for Mineralogy, Petrography and Micropedology, Geological Institute, Krijgslaan 281, B-9000 Gent, Belgium
Received 30 October 1999; received in revised form 23 February 2000; accepted 18 May 2000
Abstract
Experimental observations of changes in thermoluminescence sensitivity of a polymineral ®ne-grain sample are
reported. A repeat alpha regeneration experiment, involving multiple cycles of heating and alpha irradiation
revealed a sensitivity decrease. It was further investigated whether this eect is caused by irradiation or heating. Our
experiments show that repeated thermal treatments result in an increase in thermoluminescence (TL) sensitivity. This
is in contrast to the eect of cycles of alpha irradiation which led to a decrease in TL sensitivity. This decrease was
found to be dependent on the alpha irradiation history. 7 2000 Elsevier Science Ltd. All rights reserved.
1. Introduction
In recent years, the dierence in the thermolumines-
cence eectiveness of alpha particles compared to beta
particles or gamma rays appears to have received little
attention. Nevertheless, if there is a signi®cant alpha
contribution to the total dose-rate for a sample, it is
necessary to estimate the alpha eciency factor (a or
b-value) for the sample. This implies that the sensitivity
of the sample to alpha radiation needs to be compared
to that of beta or gamma radiation (Aitken, 1985).
In this paper, we report some preliminary obser-
vations on the TL signal induced in loess material by
alpha radiation. A sensitivity change was observed
while conducting a repeated alpha regeneration exper-
iment on the same set of discs. Both increases and
decreases in sensitivity have been observed in exper-
iments; these changes depend on the thermal and radi-
ation history of the sample. The eects of thermal
treatment on quartz samples have been studied by Lir-
itzis (1982), McKeever et al. (1983) and Bùtter-Jensen
et al. (1995). A combined eect of irradiation and
heating is the increase of the sensitivity of the 1108C
TL peak in quartz, known as the pre-dose eect. Since
its ®rst description (Fleming and Thompson, 1970), the
eect has been investigated extensively (see e.g. Zim-
merman, 1972; McKeever et al., 1985; Chen and
McKeever, 1997). It is worth mentioning here that no
pre-dose eect exists with alpha radiation (Aitken,
1985).
2. Materials and methods
The investigated material is a selected loess sample
from Rocourt (Belgium). The sample (laboratory code
TLS 26) has been dated with the TL method at
23X323X6 ka using the multiple-aliquot additive-dose
protocol and at 24X322X1 ka using the multiple-aliquot
Radiation Measurements 32 (2000) 813±817
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* Corresponding author. Fax: +32-9-264-66-99.
E-mail address: dimitri.vandenberghe@rug.ac.be (D. Van-
denberghe).