TL Glow Peak Research Articles

Influence of entire glow-curve structure of quartz on MATAC of its 110 °CTL glow peak

Understanding the complex nature of luminescent characteristics of quartz requires adequate knowledge of charge trafficking among electron and hole traps during excitation and stimulation of materials. These quantities, which are difficult to measure and mostly studied through modelling and theoretical approaches, influence the charge trafficking among the traps. This study aimed at employing a designed TL sequence, with a focus on reservoirs and competitors, to study factors affecting the shape of thermal activation curve/characteristics (TACs) of the 110 °C TL glow peak of quartz. The materials under investigations were two quartz samples from Nigeria that were annealed at 800 °C for 1 h. The results showed the structure of the TAC to be related to the nature of the glow curves (in particular high peaks) obtained during the thermal activation. The roles of reservoirs and competitors in luminescence characteristics have been used to explain the property of the 110 °C TL peak of two quartz samples in the present study. This report is among the first experimental attempts to monitor effects directly correlated to the presence of these concepts.

Determination of kinetics parameters of the main glow peaks for KMgF3:Lu and LiF:Mg phosphors after long-term high temperature storage

The isothermal decay method is useful for determining the trap activation energy in thermoluminescent material for dosimetry purposes. Recently we proposed new modified expressions for isothermal decay method. As validation of the modified expressions, after long-term (4h) high temperature storage, the activation energy of experimental TL glow peaks, KMgF3:Lu (0.17 and 0.34mol%) and LiF:Mg (0.04mol%), in the framework of the general-order kinetic was calculated. The results of the kinetics parameters were compared with those obtained by the other methods like Initial Rise (IR), Sequential Quadratic Programming Glow Curve Deconvolution (SQPGCD), deconvolution of the TL glow curves by assuming the General Order Kinetic (GOK), and Chen General-Order Kinetics method. It seems that both SQPGCD and GOK deconvolution methods give more accurate kinetics parameters values for the experimental glow curves.

Study of combinations of TL/OSL single dosimeters for mixed high/low ionization density radiation fields

In this paper we discuss and compare the potential application of combined OSL/TL measurements using 6LiF:Mg,Ti (TLD-600 is enriched of isotope 6Li which has a high cross-section for the reaction with slow neutrons) or 7LiF:Mg,Ti ( TLD-700 is enriched of 7Li isotope) and TLD-100 (natural isotopic composition) detectors. The OSL/TL duel readout of LiF:Mg,Ti as an ionization density discriminator avoids some of the difficulties inherent to the various types of discrimination mixed-field passive dosimeters, and in addition has several advantages. The preferential excitation of OSL compared to TL following high ionization density (HID) alpha irradiation, naturally explained via the identification of OSL with the “two-hit” F2 or F3 center, whereas the major component of composite TL glow peak 5 is believed to arise from a "one-hit" complex defect. This evidence allows near-total discrimination between HID radiation and low-ionization density (LID) radiation.Beta and alpha particle irradiations were carried out with 90Sr/90Y (∼500 keV average energy) and 241Am sources (4.7 MeV) respectively and neutron irradiations were carried out at the PTB (Germany) (En = 5 MeV) and RARAF (Columbia University, USA) (En = 6 MeV) accelerator facilities.The highest values of the FOM obtained was ∼30 for neutron/gamma discrimination and ∼110 for alpha/gamma discrimination using OSL/TL – peak 5 measurements in TLD-700.

Study on the photo-transfer thermoluminescence in Eu doped potassium chloride

ABSTRACTIn this work a survey of possible optical stimulation processes in irradiated KCl:Eu with a focusing on photo-transfer thermoluminescence (PTTL) effects are shown. For different wavelengths in the range from 180 to 800 nm a cycle of measurements was performed, each comprising of a TL measurement after light irradiation, a TL measurement after beta irradiation for reference purposes and a PTTL measurement. The latter was obtained by applying first a beta irradiation, then a partial readout up to a certain end temperature followed by a monochromatic light irradiation of a specific wavelength and finally a TL measurement. This procedure was repeated for different partial readout end temperatures. From the results the existence of at least four different photo-transfer processes, induced by 310, 245 and 550 nm light are deduced. The photo transfer process induced by an approximate value of 245 nm produced a TL glow peak not seen before in beta or light induced TL. Furthermore it was observed that some of the TL peaks created by light of 240 and 260 nm were strongly sensitized after a beta irradiation and a partial readout.

THERMOLUMINESCENCE RESPONSE OF GAMMA IRRADIATED SrAl2O4:Eu2+/Dy3+ NANOPHOSPHOR

In this paper, we report on the thermoluminescence response of nanocrystalline co-doped alkaline earth aluminates synthesized by combustion method using metal nitrate as precursor and urea as fuel. A broad TL glow peak was observed at 367 K with a shoulder at 400K. TL Anal program has been used for GCD curve fitting. The Kinetic parameters like, the activation energy (Eα), the frequency factor (s) and the order of kinetics were calculated for the SrAl2O4: Eu2+, Dy3+ nanophosphors. The best dopants combination was Eu (1 mol%) and Dy (2 mol%). The samples were irradiated with γ-dose in the range 20Gy–800Gy, at room temperature. A shift from 367 K to 376 K was also observed in the main peak with an increase in irradiation dose which suggest that the irradiation doses affect the distributions of traps produced by the gamma-ray irradiations. Kinetic parameters also suggest that TL glow curve in SrAl2O4: Eu2+, Dy3+ nanophosphors is obeying second order kinetics. The nanophosphors show linear response with dose.

Structural, EPR, optical and magnetic properties of α-Fe2O3 nanoparticles

α-Fe2O3 nanoparticles were synthesized by a low temperature solution combustion method. The structural, magnetic and luminescence properties were studied. Powder X-ray diffraction (PXRD) pattern of α-Fe2O3 exhibits pure rhombohedral structure. SEM micrographs reveal the dumbbell shaped particles. The EPR spectrum shows an intense resonance signal at g≈5.61 corresponding to isolated Fe3+ ions situated in axially distorted sites, whereas the g≈2.30 is due to Fe3+ ions coupled by exchange interaction. Raman studies show A1g (225cm−1) and Eg (293 and 409cm−1) phonon modes. The absorption at 300nm results from the ligand to metal charge transfer transitions whereas the 540nm peak is mainly due to the 6A1+6A1→4T1(4G)+4T1(4G) excitation of an Fe3+–Fe3+ pair. A prominent TL glow peak was observed at 140°C at heating rate of 5°Cs−1. The trapping parameters namely activation energy (E), frequency factor (s) and order of kinetics (b) were evaluated and discussed.

Behavior of various Nigerian quartz samples to repeated irradiation and heating

Abstract In the present work the sensitization of the entire glow-curve is studied in 6 different quartz samples of Nigerian origin. The investigation was applied to the un-fired “as is” samples as well as to samples fired at 900°C for 1 hour following cooling to room temperature. The results showed that in the case of “as is” glow-curve is sensitized as a whole. There is an abrupt transition from the “natural” sensitivity without any previous heating and the artificial sensitivity induced after the first heating. The sensitization is growing up strongly to the 10th heating but to a lower rate. The sensitization factor of the TL glow-peak at “110°C” was found to be linearly correlated to the higher temperature TL peaks. In the case of annealed samples there is an initial increase between the sensitivity immediately after the end of annealing and after the first heating. As the number of heating is increased up to the 10th heating the sensitization is stabilized at a constant value. The results are discussed in the frame-work of existing models and implications of the sensitization effect in various applications, while some explanations are attempted.

Luminescence determination of firing temperature of archaeological pure sand related to ancient Dian bronze casting, China

In the present paper, we have investigated the thermal history of an archaeological ‘core sand’ from a cow-shaped bronze ornament attached to a cowrie container. It was unearthed at the Lijiashan site, located in southwest China, in the area of central Yunnan, and dates from the Han period (3 c. BC–2 c. AD). We compared the archaeological sample and a control sample of the modern quartz, examining the sensitivity of 110 °C TL and 210° C TL glow peaks, and sensitization characteristics of 110° C TL and OSL. Large differences between the ‘core sand’ samples and the control sand samples have been observed in our work. The firing temperature of the ‘core sand’ was determined to be 550–700 °C. The results offer a key to understanding the ‘core sand’ as a unique casting technique in Bronze Age Yunnan. These luminesence techniques form a new method for determining the historical firing temperature of archaeological material.

On the pre-dose sensitization of the various components of the LM-OSL signal of annealed quartz; comparison with the case of 110 °C TL peak

Abstract Pre-dose sensitization of various components of LM-OSL signal of a Nigerian annealed quartz sample has been investigated along side with that of 110 °C TL peak in this work. Successive cycles of irradiations and TL/OSL readings using different heating rates were employed to attain pre-dose sensitization. The results showed that the pre-dose sensitization factor of 110 °C TL peak depends strongly on the heating rate of thermal activation. The pre-dose sensitization of 110 °C TL and all components of RT LM-OSL yield HR dependence on the sensitization after TA. This dependence was ascribed to the different heating time associated with each HR. Sensitization of LM-OSL measured at 125 °C generally does not show dependence on HR of TA. This was with the exception of components C1 and C3. Increasing sensitization pattern with increasing HR suggests a correlation between the TL glow-peak at 110 °C, the component C4 of RT LM-OSL and the component C3 of the LM-OSL signal at 125 °C. Extension of the present investigation to diverse quartz kinds from different origins was suggested in order to study the prevalence of the pre-dose sensitization on component C4 of RT LM-OSL. Finally fast heating is suggested for lower sensitization of fast component while applying OSL dating protocols.

Thermo, Iono and photoluminescence properties of 100 MeV Si7+ ions bombarded CaSiO3:Eu3+ nanophosphor

This paper reports on the thermo (TL), iono (IL) and photoluminescence (PL) properties of nanocrystalline CaSiO3:Eu3+ (1–5mol %) bombarded with 100MeV Si7+ ions for the first time. The effect of different dopant concentrations and influence of ion fluence has been discussed. The characteristic emission peaks 5D0→7FJ (J=0, 1, 2, 3, 4) of Eu3+ ions was recorded in both PL (1×1011–1×1013ionscm−2) and IL (4.16×1012–6.77×1012ionscm−2) spectra. It is observed that PL intensity increases with ion fluence, whereas in IL the peaks intensity increases up to fluence 5.20×1012ionscm−2, then it decreases. A well resolved TL glow peak at ∼304°C was recorded in all the ion bombarded samples at a warming rate of 5°Cs−1. The TL intensity is found to be maximum at 5mol% Eu3+ concentration. Further, TL intensity increases sub linearly with shifting of glow peak towards lower temperature with ion fluence.

Role of Mg in the thermoluminescence of LiF crystals grown by edge defined film fed growth (EFG) technique

LiF crystals doped with different concentration of Mg from 0 to 2000ppm have been grown by edge defined film fed growth technique. The X-ray diffraction measurement confirms the incorporation of the Mg in the lattice. Thermoluminescence and optical absorption measurements have been made on as-grown and annealed crystals after they were irradiated with a gamma dose of 15 and 1500Gy, respectively. The TL glow peak temperature and intensity increase up to 500ppm in case of the as-grown crystals and up to 1000ppm in the annealed crystals and decrease thereafter. The normalized peak height of the annealed crystals is nearly three times that of the as grown crystals for the particular concentration. Corresponding optical absorption spectra of the crystals exhibit prominent bands at 250 and 310nm. The 310nm band increases with increase in concentration of Mg and also with annealing. The changes in the TL glow curves are correlated with those of the optical absorption bands to conclude that the 310 band is due to the Mg related Z2 center.

Thermoluminescence analyses of irradiated dried sea foods using different methods of mineral separation

This research was conducted to find the most suitable parameters to separate minerals from irradiated dried shrimps and mussels (0 and 5kGy) for thermoluminescence analysis using density separation and modified acid hydrolysis (at 50°C with continuous agitation) methods. Nonirradiated samples gave TL glow curve of low intensity with peak after 300°C except dried mussel sample, which gave false positive result. This problem was absent in minerals separated by acid hydrolysis. TL ratios of all nonirradiated samples were <0.1 irrespective of method used for mineral separation. Minerals separated from irradiated samples by density separation showed very high intensity of TL glow peak before 200°C, where results from irradiated dried shrimp samples were better because of good availability of minerals. The minerals separated from irradiated samples by acid hydrolysis showed slightly low TL intensity and glow curve peak was found at about 200°C. However, acid hydrolysis method was less laborious and required less sample weight as compared to density separation method. TL ratios of all irradiated samples were >0.1 confirming the quality of minerals on TL discs.

In-homogeneity in the pre-dose sensitization of the 110 °C TL peak in various quartz samples: The influence of annealing

The pre-dose sensitization effect of the 110°C TL glow-peak of quartz is a basic tool in thermoluminescence and optically stimulated luminescence dating and retrospective dosimetry. In the present work, a homogeneity study was performed on pre-dose sensitization in grains obtained from large quartz crystals samples collected from 10 different origins. The aliquot – to – aliquot scatter of the pre-dose sensitization of the 110°C TL peak within each quartz crystal was monitored. The influence of the annealing on this scattering was also studied. Therefore, the investigation was applied to the un-fired “as is” samples as well as to samples annealed at 900°C for 1h following cooling to room temperature in air. The results showed that in the case of “as is” quartz the sensitization effect vary strongly within each aliquot of the same quartz sample. This strong variation is removed by both the high temperature annealing as well as heating up to 500°C, involved in the TL measurements. These results are generally discussed in the framework of existing models and applications of the effect.

Relative response of TL and component-resolved OSL to alpha and beta radiations in annealed sedimentary quartz

Knowledge of the relative luminescence response to alpha and beta radiation is very important in TL and OSL dating. In the present study the relative alpha to beta response is studied in a sedimentary quartz sample, previously fired at 900 degrees C for 1 h, in the dose region between 1 and 128 Gy, for both thermoluminescence (T) and linearly modulated optically stimulated luminescence (LM - OSL). The LM OSL measurements were performed at room temperature and at 125 degrees C. All OSL signals were deconvolved into their individual components. Comparison of OSL curves after alpha and beta irradiation strongly supports that quartz OSL components follow first order kinetics in both cases. In the case of TL, the relative alpha to beta response is found to be very different for each TL glow-peak, but it does not depend strongly on irradiation dose. In the case of LM OSL measurements, it is found that the relative behaviour of the alpha to beta response is different for three distinct regions, namely the fast OSL component, the region of medium OSL component originating from the TL glow-peak at 110 degrees C when stimulation takes place at room temperature and finally the region of slow OSL component. Following stimulation at ambient temperature, the relative alpha to beta response of all components was not observed to depend significantly on dose, with the value of ratio being 0.03 and a tendency to decrease with increasing dose. However, in the case of measurements performed at 125 degrees C, the relative response of the fast components is much enhanced, and for the remaining components it increases with increasing dose. Special care must be taken to examine the relative alpha to beta response of the fast component at 125 degrees C which contrasts the relative response of the TL peak at ca. 325 degrees C. The implications for the dating of annealed quartz are also briefly discussed.

Optically stimulated luminescence (OSL) and laser excited photo luminescence of electron beam treated (EBT) diamonds: Radiation sensitization and potential for tissue equivalent dosimetry

We report the first optically stimulated luminescence (OSL; blue light stimulated luminescence (BLSL) and infrared light stimulated luminescence (IRSL)) results on colored diamonds and present experimental evidence that electron beam treatment (EBT) increases the radiation sensitivity of diamonds to a level that makes them suitable for low level radiation dosimetry. A suite of seven samples was examined. These comprise a white, three brown and three yellow diamond pieces. The FT-IR spectra of these diamonds revealed the nature and concentration of nitrogen impurity. The white diamond was kept as a control. The brown and yellow (with varied saturation) diamonds were irradiated by a 1.7 MeV electron beam. These turned blue/dark green; three of them were then heated in vacuum in the temperature range of 850–900 °C for two hours. Heating turned the irradiated diamonds to lemon yellow, pink, and purple colors. The irradiated and unheated blue samples were designated as 2C and 2D. The control sample, an un-irradiated white type Ia diamond, did not yield any significant IRSL/BLSL with doses up to 100 Gy. The BLSL/IRSL sensitivity of irradiated and heat treated diamonds was very poor, and depended on the heat cycle and hence were not pursued. Sample 2C exhibited significant BLSL and negligible IRSL sensitivity. Sample 2D gave an intense orange red emission under IR excitation as also responded to BLSL. The dose response of the BLSL signal in 2C suggested a minimum detectable dose of ~ 0.1 Gy and its use as a tissue equivalent dosimeter. Based on supporting experiments such as laser excited photoluminescence, we suggest that the BLSL process in 2C is primarily driven by carbon vacancies, which release a mobile hole when excited by GR2 band in the blue region. BLSL intensity exhibited a maximum around 285 °C. Given that TL glow peak also occurs near this temperature and that the nitrogen–interstitial carbon (N–Ci) complex also forms at this temperature (as reported in the literature), and it appears that the e–h recombination at sites with N–Ci complex could be involved in BLSL production. Laser excited photoluminescence (PL) at wavelengths 325, 514 and 785 nm and absorption spectra in UV–Visible range gave insights into the contrasting BLSL/IRSL responses of 2C and 2D. These differences were due to differences in nitrogen impurity complexes and the concentration of carbon vacancies produced by EBT in 2C and 2D. In 2D, the presence of Ni as NE8 center (four nitrogens coordinated to Ni) giving 800 nm emission on 785 nm excitation, appeared to suppress BLSL and sensitize IRSL in the orange window.

Electron transfer process betweenCe3 + donor andYb3 + acceptor levels inthe bandgap of Y3Al5O12 (YAG)

Thermoluminescence (TL) properties ofCe3 + andYb3 + co-dopedin Y3Al5O12 (YAG) were studied with the aim of determining the location of energy levels ofCe3 + andYb2 + relative to the bottom of the conduction band (CB) and the topof the valence band (VB) of YAG. The TL glow peak at about180 °C when heating rateβ = 1°C s − 1 was assigned toelectron release from Yb2 + , indicating that Yb3 + acts as an electron trap. The trap depth, which is the depth of the ground-state level ofYb2 + below the bottom of the CB, was derived from the temperatures of the maximum of the TLglow peak at different heating rates. The value is, within the experimental and theoreticaluncertainties, in good agreement with that derived from the charge transfer energy. Thermoluminescence excitation spectroscopy(TLES) was used to establish the location of energy levels ofCe3 + . From the derived data the energy level diagram ofYAG:Ce3 + ,Yb3 + is constructed and possible electron transfer processes are discussed.

Thermoluminescence of aluminum oxide co-doped with terbium and thulium obtained via combustion synthesis

In this work thermoluminescent properties of α-Al2O3 samples doped with Tb3+ and Tm3+, prepared by the combustion synthesis route, were studied. Samples were prepared by mixing stoichiometric amounts of aluminum nitrate, urea and dopants with different amounts of terbium and thulium nitrates varying from 0 to 0.15 mol%. The mixture was ignited in a muffle furnace at low temperature (500 °C). After the combustion, the samples were sintered at 1400 °C for 4 h in order to obtain the pure α-phase crystalline structure. The TL response of these samples for Co-60 gamma radiation was evaluated. It was observed a TL glow peak around 220 °C and a linear response for doses in studied range of 0.1–1 Gy. It was observed that the 0.1 mol% concentrations of both dopants present the highest TL sensitivity. The sensitivity of the co-doped (0.10 mol%) samples is 5 times higher than the 0.1 mol% Tm-only doped Al2O3 and 40 times higher than the sample doped only with 0.1 mol% of Tb. These results strongly suggest that the Al2O3:Tm–Tb, prepared through the combustion method, is a potential material for TL radiation dosimetry.

Thermally assisted OSL from deep traps in Al2O3:C

The present work suggests an alternative experimental method in order to not only measure the signal of the deep traps in Al 2 O 3 :C without heating the sample to temperatures greater than 500 °C, but also use this signal for high dose level dosimetry purposes as well. This method consists of photo transfer OSL measurements performed at elevated temperatures using the blue LEDs (470 nm, FWHM 20 nm) housed at commercial Risø TL/OSL systems, after the sample was previously heated up to 500 °C in order to empty its main TL dosimetric trap. The influence of this procedure on specific features such as glow curve shape and sensitivity of the main TL glow peak was also studied.

Possibility of pure thermal sensitization in the pre-dose mechanism of the 110 °C TL peak of quartz

The role of thermal activation in the pre-dose sensitization of the 110 °C TL glow peak of quartz has been hypothesized to transfer holes from reservoir centre, R, to luminescence centre, L. But, the thermal treatment has been reported to sensitize this peak, also, in an independent mode. So, a comparative analysis of the impact of thermal and pre-dose treatment on the TL properties of the 110 °C signal, observed by various workers, has been undertaken in this paper. Also experiments were carried out to observe thermal sensitization component at the temperatures which are used in the pre-dose sensitization measurements. The study seems to support the existence of an inherent pure thermal sensitization component in the pre-dose sensitization mechanism.

The effects of heating rate on the dose response characteristics of TLD-200, TLD-300 and TLD-400

In the given study; the effects of heating rates on the dose response characteristics of CaF 2:Dy (TLD-200), CaF 2:Tm (TLD-300) and CaF 2:Mn (TLD-400) crystals have been investigated using the dose dependence curve and dose response function f( D). It was observed from the dose response functions that the linearity and behaviour of the TL glow peaks of TLD-200 and TLD-400 are affected, but the TLD-300 is not affected from the heating rate.