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LiF crystal doped with magnesium (Mg), copper (Cu) and phosphorous (P) was grown in the form of multicrystalline sheet using Edge-defined film-fed growth (EFG) technique for dosimetry application. These crystals were grown in argon gas atmosphere using graphite crucible and stainless steel die. Dosimetry peak was observed at 210 °C for as-grown crystal. As reported earlier LiF:Mg, Cu, P is a highly sensitive material but losses its sensitivity if annealed at temperature above 240 °C. In this paper, the effect of annealing temperature on thermoluminescence glow-curve structure, maximum peak temperature, peak height and integrated area of the glow peak of EFG grown samples was investigated in detail. Annealing temperature range from 220 °C to 500 °C was considered for the study. Experimental results of the obtained glow curve show that with increase in annealing temperature, glow peak shift towards higher temperature region with substantial increase in TL intensity. Annealing at 500 °C for 10 min gave maximum TL intensity with main dosimetry peak positioned at 233 °C. Change in the defect structure with different pre-annealing temperature was analysed using trapping parameters. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

A detailed TL investigation on MgO:Li,Tb,Sm phosphor has been carried out by studying several TL characteristics - TL glow curve structure, dose response, linearity dose behaviour, fading and reproducibility. TL glow curve structure of the phosphor reveals the presence of two TL glow peaks. The main TL glow peak of high intensity is observed at high temperature side i.e. at 162 °C and another peak of low intensity is observed at 316 °C. Further, the effect of dose on TL response of the phosphor has been studied and a new behaviour is noticed. With increasing doses, the position of main TL glow peak is similar while the second TL glow peak vanishes at higher doses. A linear TL response is observed from 10 Gy–700 Gy and becomes sublinear above 700 Gy. Low TL fading characteristics and good reproducibility have also been observed. Encouraging results suggest the applicability of doped MgO phosphor for the detection of gamma rays. • MgO:Li,Tb,Sm phosphor is synthesized using combustion method. • TL dose response is studied in the dose range 10 Gy–2000 Gy. • Single TL glow peak is present at higher doses (>200 Gy). • Linear TL dose region is observed in the dose range 10 Gy–700 Gy. • Interesting TL results are favorable for high dose gamma dosimetry. [ABSTRACT FROM AUTHOR]

• TL properties of perovskite NaMgF 3 :Tb synthesized using solid state reaction method and melting method have been investigated. • TL properties of NaMgF 3 :Tb irradiated with gamma rays is reported firstly. • Single TL glow curve structure, linear TL response for 10 Gy – 500 Gy, low TL fading characteristics has been observed for the sample prepared using melting method. • NaMgF 3 :Tb synthesized using melting method is a potential TL dosimeter for the detection of gamma rays. NaMgF 3 is a recognized sensitive thermoluminescence (TL) dosimeter but it shows fading at room temperature which limits its use as a radiation dosimeter. It is important to improve this parameter of NaMgF 3 for its potential application in the field of radiation dosimetry. Thus, the current work focuses on enhancing the dosimetric properties of NaMgF 3 exclusively the TL fading characteristics. In the present study, Tb doped NaMgF 3 has been synthesized by two different methods i.e. solid state reaction method (SSR) and melting method (MT). A comparative and detailed TL studies have been carried out after irradiation with gamma rays which has not been reported so far. Detailed analysis of TL and Photoluminescence (PL) properties reveal that NaMgF 3 :Tb prepared via MT shows good luminescence properties in comparison to SSR and previously reported results. Thus, Tb doped NaMgF 3 synthesized by melting method can be a potential dosimeter for the detection of gamma rays. [ABSTRACT FROM AUTHOR]

MgO is drawing considerable attention owing mainly due to its tissue equivalency (Z eff = 10.8) and excellent luminescence response. In this work, we report the synthesis and investigation of a highly sensitive MgO: Li, Sm phosphor in nanocrystalline form for TL dosimetry application. The structural and morphological study has been done using X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). TL intensity of gamma irradiated MgO nanophosphor increases with doping of Li and further improves by co-doping with Sm. The MgO: Li, Sm nanophosphor exhibit TL glow curve structure having isolated single peak at 169 °C and linearity in the low dose (13 mGy-5 Gy) as well as high dose range (10–1000 Gy). The TL structure and peak position remains stable at all doses. The phosphor shows excellent stability (low fading rate) and repeatability. TL intensity of MgO: Li, Sm is 12 times higher than that of commercially available LiF: Mg, Ti (TLD 100) and almost equivalent to LiF: Mg, Cu, P (TLD-700 H). This may be attributed to the formation of greater number of density of traps and suitable trapping levels with optimum dopant selection in MgO nanophosphor. The incorporation of the Sm3+ has improved the TL intensity manifold with appearance of desired isolated single peak. The photoluminescence (PL) spectra confirm the Sm3+ emission at 566, 603, 651 and 708 nm with an excitation wavelength of 315 nm. Further the role of dopants has been discussed on the basis of charge transfer mechanism and corelated with associated kinetic parameters for better understanding of TL process. The newly explored MgO: Li, Sm nanophosphor has shown attractive TL dosimetry properties owing to its high sensitivity, stable glow curve structure, dose linearity, low fading and repeatability which meet all the requirement to establish this as a next generation TL phosphor for medical and personal dosimetry application. [Display omitted] • Synthesis of MgO: Li, Sm phosphor in nanocrystalline form using solution combustion method. • TL sensitivity of MgO: Li, Sm nanophosphor is ∼12 times higher than TLD- 100 and close to TLD-700 H. • The phosphor show stable glow curve structure and good linearity. • The Sm3+ has improved the TL intensity manifold with appearance of isolated single TL peak. [ABSTRACT FROM AUTHOR]

Europium (Eu) doped LiF crystals have been grown by the Edge-defined film fed growth (EFG) technique. The designing and installation of the furnace used for the growth of the crystals have been discussed in detail. In the present study, Eu (Eu 2 O 3 ) has been doped in LiF in different concentration (0.02–0.2 wt %). X-ray diffractometry (XRD) and Energy Dispersive X-ray (EDX) spectroscopy confirms the incorporation of Eu in LiF. The influence of Eu on LiF has been investigated through photoluminescence (PL), thermoluminescence (TL) and electron paramagnetic resonance (EPR) in as-grown and annealed crystals. PL emission spectra shows the presence of both Eu 3+ and Eu 2+ form in the as-grown crystals which is confirmed by EPR results. Whereas, in annealed crystals, Eu is present predominantly as Eu 2+ form. This suggests that growing crystals at high temperature (∼900 °C) in argon gas atmosphere through EFG technique favours the reduction of Eu 3+ → Eu 2+ . This reduction phenomenon has been explained on the basis of charge compensation model. TL study of the LiF: Eu (0.02–0.2 wt %) crystals has been done after irradiation with Co 60 gamma rays. In this study, it has been observed that the TL intensity as well as glow curve structure of LiF: Eu crystals are a strong function of Eu concentration. The maximum TL is observed at Eu concentration of 0.05 wt% at which a well defined glow curve structure with a prominent peak at 185 °C and a small peak at 253 °C. Beyond this concentration (0.05 wt %), TL intensity decreases due to aggregation of defects in the host. The peak at 185 °C in LiF: Eu (0.05 wt %) is certainly due to the presence of Eu 2+ associated defects which is also supported by the PL spectra. It has been observed that Eu doping have a key role in creation of more defect levels which lead to the increased number of electron and hole traps. Further, trapping parameters are analysed using glow curve deconvolution method to have an insight study of TL phenomena. Further, TL glow curve structure of as-grown and annealed crystal are distinct which may be attributed to the nature of defect traps formed inside the LiF. [ABSTRACT FROM AUTHOR]

In the present work, the thermoluminescence (TL) properties of Yb doped CaSiO 3 phosphor exposed to gamma rays and carbon (C) ion beam have been reported. The phosphor has been synthesized using solid-state reaction method. The formation and surface morphology of the phosphor have been studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) respectively. The optical band gap of the phosphor is determined using UV–Visible spectroscopy. TL properties on Yb doped CaSiO 3 phosphor irradiated with carbon ion beam has been reported first time. Different TL properties like TL glow curve, dose response, fading etc. have been investigated in detail. The TL glow curve of CaSiO 3 :Yb phosphor consists of two prominent glow peaks. Under gamma irradiation, the main dosimetric peak is centered at 141 °C and other peak is centered at 265 °C. The dose response behaviour has been studied in the range 10 Gy–1000 Gy. However, C ion beam irradiated phosphor also consists similar TL glow curve structure with glow peaks shifted towards high temperature side (approx. 50 °C). The dose response behaviour of C ion beam irradiated phosphor has been examined in the ion fluence range varying from 5 × 109–5 × 1012 ions/cm2. A track interaction model is used to explain the sublinearity at higher fluences of carbon ion beam. Different ion beam parameters have been analyzed using Monte-Carlo simulation-based SRIM code. A comparative TL study of the phosphor irradiated with gamma rays and carbon ion beam suggests that gamma irradiated phosphor has shown better TL properties such as high TL sensitivity, good linear dose response (10 Gy–500 Gy), stable TL glow curve structure and low fading. Various TL trapping parameters i.e. order of kinetics, activation energy and frequency factor have been calculated using Chen's peak shape method to analyze the nature of TL traps responsible for showing different behaviour of the phosphor towards both the radiations. Good TL properties of CaSiO 3 :Yb phosphor supports its possible use in gamma dosimetry. • A phosphor CaSiO 3 :Yb is developed using solid state reaction method. • A comparative TL studies of CaSiO 3 :Yb phosphor under gamma and carbon ion beam irradiation is carried out in detail. • Effect of carbon ion beam on Yb doped CaSiO 3 phosphor is reported for the first time. • Stable TL glow peaks have been observed under both the irradiations. • Encouraging TL results of CaSiO 3 :Yb phosphor makes it a promising TL detector for gamma radiations. [ABSTRACT FROM AUTHOR]

Thermoluminescence (TL) properties of LiF: Mg, Cu, Si phosphor prepared in multicrystalline form using edge defined film fed growth (EFG) technique has been investigated. The effect of preparation route on TL properties and thermal stability has been studied. To improve the TL dosimetry properties, phosphor is subjected to different annealing temperatures ranging from 250 °C to 450 °C. The shape of the glow curve structure and peak temperature remains similar at different annealing temperatures, however peak intensities vary. The consistency in the glow curve structure with annealing temperature elucidate that TL trapping states are stable in nature. Thermal annealing at 300 °C for 10 min gives maximum TL intensity with main dosimetry peak at 209 °C. The TL intensity of the main dosimetry peak is increased by a factor of five as compared to as-grown crystal. The thermal stability of LiF: Mg, Cu, Si is found to be better than LiF: Mg, Cu, P. Trapping parameters are calculated to have an insight study of defect states. A simple glow curve structure, tissue equivalency, thermal stability, low residual signal, linear response and reusability makes LiF: Mg, Cu, Si a suitable phosphor for radiation therapy, radio diagnostics and personnel dosimetry applications. [ABSTRACT FROM AUTHOR]

Fluoroperovskites are an important class of thermoluminescence (TL)/optically stimulated luminescence (OSL) materials known for their high sensitivity and other good characteristics particularly when doped with a suitable impurity. Fluoroperovskites have not yet been explored for heavy charged particle irradiation like carbon which is commonly used for cancer treatment. In the current work, TL and OSL properties of 85 MeV carbon ion beam irradiated NaMgF 3 :Tb samples have been investigated in detail at different fluences. Undoped and Tb3+ (0.5 mol%) doped NaMgF 3 samples have been synthesized by the melting method. The formation of the material is confirmed using the XRD technique. The crystallite size of undoped and Tb3+ doped NaMgF 3 samples are estimated to be 100 nm and 89 nm respectively. TL studies reveal that undoped NaMgF 3 shows a well-isolated TL glow peak centered at 412 K while Tb3+ doped NaMgF 3 shows more intense TL glow peak at 416 K with a small shoulder peak at 481 K along with a new peak at 647 K. Further, TL glow curves have been analyzed for 85 MeV carbon ion irradiated samples of NaMgF 3 for low fluences (1 × 105–1 × 107 ions/cm2) and high fluences (2 × 109–5 × 1012 ions/cm2) to study the dose-response. CW-OSL decay curves of 85 MeV carbon ion irradiated undoped and Tb3+ doped NaMgF 3 samples show high OSL intensity under blue light stimulation. The OSL dose-response has been recorded at high (1 × 108–1 × 1010 ions/cm2) and low (1 × 105–1 × 107 ions/cm2) fluences. Linear TL and OSL behaviour in the range 1 × 105–5 × 106 ions/cm2 has been observed. Also, other properties like batch homogeneity and fading studies have been carried out. The related TL/OSL kinetic parameters were determined. Analysis of TL/OSL properties of NaMgF 3 :Tb suggests that it exhibits appropriate properties for carbon ion beam dosimetry for its utilization in medical applications. • Nearly tissue equivalent high sensitive fluoroperovskite NaMgF 3 :Tb is developed. • TL/OSL studies of carbon ion irradiated NaMgF 3 :Tb is reported for the first time. • Linear TL and OSL response in low fluence region has been observed. • NaMgF 3 :Tb is a promising radiation detector for carbon ion beam dosimetry. [ABSTRACT FROM AUTHOR]