Resolving the limitation of the peak fitting and peak shape methods in the determination of the activation energy of thermoluminescence glow peaks A.M. Sadek a,n , H.M. Eissa a , A.M. Basha b , G. Kitis c a Ionizing Radiation Metrology Department, National Institute for Standards, Cairo, Egypt b Physics Department, Faculty of Science, Fayoum University, Fayoum, Egypt c Nuclear Physics and Elementary Particles Physics Section, Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Makedonia, Greece article info Article history: Received 28 August 2013 Received in revised form 8 October 2013 Accepted 12 October 2013 Available online 22 October 2013 Keywords: Thermoluminescence Glow curve analysis Peak shape methods OTOR model Lambert W function abstract An overview of the successes and failure of the computerized glow curve deconvolution (CGCD) and the peak shape methods in describing the glow peaks generated from the fundamental one trap-one recombination center (OTOR) model was discussed. Also, the existing method, and a new developed one, to test the applicability of the existing thermoluminescence (TL) expressions to describe the glow peaks were discussed. The new TL expressions deduced by Kitis and Vlachos ([17] G. Kitis, N.D. Vlachos, Radiat. Meas. 48 (2013) 47–54) were tested in the cases in which the other existing TL expressions failed. The results showed that the error in the calculated activation energy (E) using the existing expressions may reach up, in some cases, to 50%. While, using the new TL expressions, the error in the calculated E did not exceed 0.5%. & 2013 Elsevier B.V. All rights reserved. 1. Introduction The clear knowledge of the kinetics parameters of the thermo- luminescence (TL) material is essential for many applications in TL dosimetry [1–4]. Thus, several methods were developed to deter- mine the kinetics parameters of a single glow peak e.g., the peak shape methods and the glow peak fitting method. These methods are based on the well-known model for explaining a single TL glow peak, the one trap-one recombination center (OTOR) [5,6]. This model consists of an electron trapping state, the conduction band and hole center. Unfortunately, the differential equations describing this model cannot be solved analytically. Thus, using simplifying assumptions, the OTOR model is reduced to either first- or second-order kinetics expressions but not to intermediate kinetics orders. For the intermediate cases, the general-order kinetics (GOK) expression was developed [7] which is an empirical expression. Application of GOK has been most commonly prac- ticed in this connection for over two decades. However, recently the mixed-order kinetics (MOK) [8] has getting substantial atten- tion due to the fact that the MOK has a physical basis [9,10]. The success and failure of the general- and mixed- order kinetics analytical expressions to fit numerically generated TL glow peaks based on the OTOR model, as well as more compli- cated models, have also been investigated [9,11–16]. The general conclusion from these attempts is that both the general- and mixed-order kinetics fit numerically generated glow peaks well in terms of the limits of the first- and the second-order kinetics but deviate in the intermediate kinetic orders. Furthermore, all analy- tical peak model expressions fail to describe the glow peak in the cases in which the re-trapping probability becomes greater than the recombination one (A n ⪢A m ), and the sample dose is in the saturation range (N ¼ n o ). Recently, Kitis and Vlachos [17] have developed new general semi-analytical expressions for TL glow peak based on the OTOR level model using the Lambert W function. The aim of this study is to use these new developed expressions to attempt to resolve the limitation of the existing TL expression in describing the OTOR glow peaks. 2. OTOR level model The process of TL consists of the transition of electrons released thermally from the electron traps into the conduction band from which they may either recombine with holes in the center or re-trap, namely fall back into the traps. Halperin and Braner [6] wrote the set of three simultaneous differential equations governing the Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence 0022-2313/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jlumin.2013.10.031 n Corresponding author Tel.: þ20 1114077224. E-mail addresses: dr_amrsadek@hotmail.com, amrsadeksaleh@gmail.com (A.M. Sadek). Journal of Luminescence 146 (2014) 418–423