Radiation Measurements 41 (2006) 910 – 916 www.elsevier.com/locate/radmeas Comparison of experimental and modelled quartz thermal-activation curves obtained using multiple- and single-aliquot procedures George Kitis a , Vasilis Pagonis b, ∗ , Reuven Chen c a Nuclear Physics Laboratory, Aristotle University of Thessaloniki, 54124-Thessaloniki, Greece b Physics Department, McDaniel College, Westminster, MD 21157, USA c Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel Received 14 August 2005; received in revised form 24 March 2006; accepted 17 April 2006 Abstract This paper presents the results of a broad study of the thermal-activation characteristics of three quartz samples of different origin. The thermal-activation characteristics of synthetic, sedimentary and Arkansas quartz are measured as a function of several experimental parameters and over the temperature range 20.500 ◦ C using both multiple-aliquot and single-aliquot techniques. The studies are carried out also as a function of the thermal preparation of the samples, for “as-is” samples, for samples fired at temperatures of 500 and 900 ◦ C. Additional experimental parameters varied in this study include the test dose used in measuring the thermal activation curves and the temperature interval between successive heating of the samples. The results of this experimental study for all three quartz samples are interpreted by using a simple modified Zimmerman model for quartz consisting of 2 electron traps, a luminescence center and three hole reservoirs. The results are also discussed within the recently published complex theoretical quartz model by Adamiec (2005. Investigation of a numerical model of the pre-dose mechanism in quartz. Radiat. Meas. 39, 175–189), which is based on a luminescent center, three electron traps and three reservoir hole traps. © 2006 Elsevier Ltd. All rights reserved. 1. Introduction The study of sensitivity changes occurring in quartz during the application of single- and multiple-aliquot dating techniques is of fundamental importance in TL and OSL. There have been very few comparative studies of the sensitization properties of quartz of different origins, under different “predose” irradia- tions and/or heating of the samples to various temperatures. In a recent paper Kitis et al. (2006) presented a compara- tive study of the predose effect for three types of quartz of different origins. Curves of TL versus dose, and sensitivity S versus predose curves were obtained for the dose range of 0.1 <D< 400 Gy, as well as for samples which underwent a combined predose irradiation and a subsequent heat treatment to 500 ◦ C. The results of that comparative study were explained by simulating the complete experimental protocol using a mod- ified Zimmerman (1971) model. ∗ Corresponding author. Tel.: +1 410 857 2481; fax: +1 410 386 4624. E-mail address: vpagonis@mcdaniel.edu (V. Pagonis). 1350-4487/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2006.04.007 The purpose of the present paper is to extend the experimen- tal work by Kitis et al. (2006) to the thermal-activation charac- teristics (TACs) of synthetic, sedimentary and Arkansas quartz. The TACs are measured as a function of several experimental parameters, namely using multiple-aliquot and single-aliquot techniques, annealing of the samples, different test doses, and various temperature intervals between successive heating of the samples. The experimental results of this study are found to be in agreement with a modified Zimmerman model containing three hole reservoirs. In a recently published comparative study, Adamiec (2005) studied the thermal-activation characteristics (TACs) of several types of quartz and compared the experimental results with a theoretical model similar to the model by Bailey (2001). Our experimental results are also discussed within the context of this theoretical model. 2. Experimental procedure The materials used in the present study were high-purity syn- thetic quartz, natural Arkansas quartz of hydrothermal origin