Synthesis,characterisation and dosimetric evaluation of MgB4O7 glass as thermoluminescent dosimeter

This study presumably reports the dosimetric properties of MgB₄O₇ glass system. A series of MgB₄O₇ glass samples with nominal compositions XMgO-(100-X) B₂O₃, with X?=?35, 40 and 45?mol% was successfully synthesied using conventional melt quenching method. The presence of broad humps and absence of any sharp peak in typical X-ray diffraction patterns confirm the amorphous nature of the synthesised glass samples. Good glass forming ability, 0.55, of the mixture resulting in a glass with excellent glass stability, 1.4, was observed. Thermoluminescence glow curve was observed to be simple with a single well defined dosimetric peak around 200°C. The dose response was found to be linear from 6?µGy to 0.5?kGy when irradiated to Cs-137 gamma rays. Considerably satisfying thermoluminescent (TL) characteristics suggests that the MgB₄O₇ glass could be recommended as a TL dosimeter.     

The effects of thermal treatments on the thermoluminescence properties of biogenic minerals present in the seashells

In this study, thermoluminescence (TL) properties of the biogenic minerals present in the seashell samples at different temperatures and annealing times have been studied. Three explicit peaks are seen in the glow curves roughly at 100°C, 180°C, and 380°C. One of the prominent results is that annealing above 600°C affects enormously the TL intensity, whereas no remarkable TL intensity is observed for unannealed samples. The highest intensity and area under the curve were observed at 700°C annealing temperature, and 180 minutes annealing time and 1500 times bigger than the unannealed samples. A linear dose response is observed between 2.4 and 72?Gy and beyond this value, a sublinear relation is observed. Unfortunately, a huge decrease in TL intensity is observed about 51% of its initial value, after 5 hours of storage time.     

Bismuth silicate glass as host media for some selected rare-earth ions and effects of gamma irradiation

Ultraviolet, visible and infrared spectral measurements were used to investigate prepared undoped and rare-earth doped (2.5%) bismuth silicate glasses (80% Bi₂O₃–20%SiO₂) before and after being subjected to gamma irradiation (8?Mrad). The base bismuth silicate glass reveals strong extended UV–near visible absorption bands which are attributed to the presence of trace iron impurities in the raw materials together with absorption due to sharing of Bi³⁺ ions. The RE-doped samples show the same strong UV–near visible bands as the undoped glasses beside extra narrow characteristic bands mostly in the visible and near-infrared regions due to the respective studied rare-earth ions. The base undoped and all RE-doped samples except CeO₂ sample reveal quite resistance to the effect of gamma irradiation due to heavy atomic mass Bi³⁺ ions present in high content (80%) and the rare-earth ions are known to be weakly affected due to the known 5s, 5p shielding. The exceptional effect of CeO₂-doped sample is related to the ability of Ce³⁺ ions to change its oxidation state through photochemical reaction by irradiation or exchange with Fe³⁺ present as trace iron impurities. The FT infrared spectra of the prepared glasses reveal characteristic absorption bands which are related to the silicate groups together with the sharing of vibrational modes due to Bi–O groups. The IR spectra are slightly affected by gamma irradiation indicating the stability of the structural network groups consisting of SiO₄ and BiO₆ units.     

Influence of modifier oxide on spectroscopic and thermoluminescence characteristics of Sm ion in antimony borate glass system

Sb₂O₃-B₂O₃:Sm³⁺ glasses mixed with three different modifier oxides viz., PbO, CaO and ZnO were prepared. Optical absorption, photoluminescence and thermoluminescence (TL) spectra of these glasses have been recorded at room temperature. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt parameters Ω₂, Ω₄ and Ω₆ have been evaluated. The Judd-Ofelt theory could successfully be applied to characterize the absorption and luminescence spectra of these glasses. From this theory, various radiative properties like transition probability A, branching ratio β_r, the radiative lifetime τ_r, and the emission cross-section σ^E for various emission levels of these glasses have been determined and reported. An attempt has also been made to throw some light on the relationship between the structural modifications and luminescence efficiencies of all the three glasses. The analysis of TL data indicates high non-radiative losses in ZnO mixed glasses.     

Evaluation of the dosimetric characteristics of a radiophotoluminescent glass dosimeter for high-energy photon and electron beams in the field of radiotherapy

We aimed to evaluate the suitability of a glass dosimeter (GD) for high-energy photon and electron beams in experimental and clinical use, especially for radiation therapy. We examined the expanded dosimetric characteristics of GDs including dose linearity up to 500 Gy, uniformity among GD lots and for individual GDs, the angular dependence, and energy dependence of 4 therapeutic x-ray qualities. In addition, we measured the dosimetric features (dose linearity, uniformity, angular dependence, and energy dependence) of the GD for electron beams of 10 different electron energy qualities. All measurements with the exception of dose linearity for photon beam were performed in a water phantom. For high-energy photon beams, dose linearity has a linear relationship for a dose ranging from 1 to 500 Gy with the coefficient of determination; R² of 0.998. The uniformity of each GD of dose measurements was within ±0.5% for four GD lots and within ±1.2% for 80 GDs. In terms of the effects of photon beam angle, lower absorbed doses of within 1.0% were observed between 60° and 105° than at 90°. The GD energy dependence of 4 photon beam energy qualities was within ±2.0%. On the other hand, the result of the dose linearity for high-energy electron beams showed well fitted regression line with the coefficient of determination; R² of 0.999 between 6 and 20 MeV. The uniformity of GDs exposed to the nominal electron energies 6, 9, 12, 16, and 20 MeV was ±1.2%. In terms of the angular dependence to electron beams, absorbed doses were within 2.0% between 60° and 105° than at 90°. In evaluation of the energy dependence of the GD at nominal electron energies between 5 and 20 MeV, we obtained responses between 1.1% and 3.5% lower than that for a cobalt-60 beam. Our results show that GDs can be used as a detector for determining doses when a high-energy photon beam is used, and that it also has considerable potential for dose measurement of high-energy electron beam.     

Improving dosimetric properties of tellurite glasses

Thermoluminscence (TL) properties of quaternary tellurite glass in the form 80(TeO₂)–5(TiO₂)–(15−x)(WO₃)–(x)A_nO_m where A_nO_m=Nb₂O₅, Nd₂O₃, Er₂O₃ and x mol% have been measured. TL main dosimetry peak for each produced glass sample were investigated for ⁶⁰Co gamma rays. Dosimetric properties of the quaternary tellurite glasses have been measured as a function of different compositions of the glass system in different rare earth oxides concentration by using thermoluminescence (TL) detection technique.     

Influence of nitrogen implantation on thermoluminescence of synthetic quartz

Thermoluminescence (TL) of synthetic quartz exposed to beta irradiation following implantation with 60?keV N⁺ ions at fluences ranging between 1?×?10¹⁴ and 5?×?10¹⁵?ions/cm² is reported. The glow curve measured at 5°C/s typically consists of a prominent peak near 110°C, studied in this work, and minor glow peaks at around 130°C and 190°C. The TL intensity of the main peak increased both with implantation and with fluence of implantation. The dependence of the intensity on heating rate and fluence suggests that the implantation introduces new defects that may possibly act as recombination centres. The increase in TL intensity with the heating rate exhibited by implanted samples has been observed in other luminescence materials. This anti-quenching phenomenon has been described as a competition effect between multiple luminescence pathways in luminescence materials. Kinetic analysis of the main glow peak using the initial rise, various heating rate and glow curve deconvolution methods shows that the activation energy of the main peak is about 0.7?eV with no systematic change due to ion fluence.     

Intrinsic dosimetry: Elemental composition effects on the thermoluminescence of commercial borosilicate glass

Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering this dose in tandem with the physical characteristics of the radioactive material housed within the container, this method can provide enhanced pathway information for interdicted radioactive samples. Thermoluminescence (TL) dosimetry was used to measure ionizing radiation dose effects on stock borosilicate glass. Differences in TL glow curve shape and intensity were observed for glasses from different geographical origins. The different TL signatures strongly correlated with the concentration of alkaline earth metals and the ratio of sodium to the total amount of alkali metal present in the borosilicate glass.     

热释光方法在古陶瓷鉴定中的应用

中国古陶瓷是国际性的艺术收藏品,它的真伪判定是一个关键而且是首要的问题.传统的“目鉴”方法由于它的主观性,结论不容易取得共识,也不易对采用现代高新技术制作的赝品做出准确的鉴别.对古陶瓷进行现代的科技方法鉴定是必然的趋势,而且已取得重要的进展.热释光检测方法是一种绝对断代方法,它不依赖于数据库的建立.经过40余年的发展,热释光技术已从早期的常规方法发展出前剂量方法和高温峰测定方法,一种快速无损的二氧化碳激光加热检测法亦己取得重要的进展.     

热释光方法在古陶瓷鉴定中的应用

中国古陶瓷是国际性的艺术收藏品,它的真伪判定是一个关键而且是首要的问题.传统的“目鉴”方法由于它的主观性,结论不容易取得共识,也不易对采用现代高新技术制作的赝品做出准确的鉴别.对古陶瓷进行现代的科技方法鉴定是必然的趋势,而且已取得重要的进展.热释光检测方法是一种绝对断代方法,它不依赖于数据库的建立.经过40余年的发展,热释光技术已从早期的常规方法发展出前剂量方法和高温峰测定方法,一种快速无损的二氧化碳激光加热检测法亦已取得重要的进展.     

Effect of ion irradiation on the thermoluminescence properties of K2Ca2(SO4)3 phosphor

This paper presents the thermoluminescence (TL) studies of ion-irradiated potassium–calcium mixed sulfate phosphor. The sample was prepared by the solid-state diffusion method. The X-ray diffraction study of the prepared sample suggests an orthorhombic structure with an average particle size of 0.16 μ m. The samples were irradiated with 1.2 MeV argon ions at fluences varying between 10¹¹ and 10¹⁵ ions/cm². The argon ions penetrate to a depth of 1.93 μ m and lose their energy mainly via electronic stopping. Due to ion irradiation, a large number of defects such as oxygen vacancies, radicals and color centers are formed in the sample. TL glow curves were recorded for each of the ion fluences. A linear increase in the intensity of TL glow peaks was found with an increase in the ion dose from 72 kGy to 720 MGy. The kinetic parameters associated with the prominent glow peaks were calculated using glow curve deconvolution, different glow curve shapes and sample heating rate methods.     

用远场法研究自由旋气动窗口的光学特性

 采用He-Ne激光,对穿过自由旋气动窗口的远场聚焦光斑进行图象采集和数据处理,研究本气动窗口对透过其输出通道的激光束所带来的偏转和随机抖动现象,计算分析气动窗口对激光束发散特性的影响,定义和实验研究气动窗口的光束质量β因子。同时,分析讨论气动窗口对激光束远场聚焦光斑光强分布的影响,并提出气动窗口光束质量和气动窗口设计的进一步研究思路。     

Flexible sheet with radiophotoluminescence glass beads for remotely monitoring high beta-surface-contamination

A flexible sheet was made with radiophotoluminescence (RPL) glass beads on an experimental basis for visualization of high beta-surface-contamination. A simple RPL observation system for remote contamination monitoring was constructed with a homemade UV floodlight and a commercially available digital camera with supplementary optical lenses and filters. In preliminary experiments, RPL images were well observed with the digital camera of the present system. Their precise RPL intensity was determined after the correction of nonlinear response of the camera. It was expected from experiments that RPL images of beta-surface-contamination could be quantitatively evaluated through calibration, i.e., the conversion of camera images to dose data on the sheet-type glass dosimeter.     

用远场法研究自由旋气动窗口的光学特性

采用He-Ne激光,对穿过自由旋气动窗口的远场聚焦光斑进行图象采集和数据处理,研究本气动窗口对透过其输出通道的激光束所带来的偏转和随机抖动现象,计算分析气动窗口对激光束发散特性的影响,定义和实验研究气动窗口的光束质量β因子。同时,分析讨论气动窗口对激光束远场聚焦光斑光强分布的影响,并提出气动窗口光束质量和气动窗口设计的进一步研究思路。     

Geminga contribution to the cosmic-ray positron excess according to the gamma-ray observations

We attempt to interpret the cosmic-ray positron excess by injection from the nearby pulsar Geminga, assuming a two-zone diffusion scenario and an injection spectrum with a low energy cutoff. Since the high energy positrons and electrons from Geminga can induce γ rays via inverse Compton scattering, we take into account the extended γ-ray observations around Geminga from HAWC for ∼10 TeV and from Fermi-LAT for ${ \mathcal O }(10)$ GeV. According to the extended γ-ray observation claimed by an analysis of Fermi-LAT data, we find that Geminga could explain the positron excess for a 30% energy conversion efficiency into positrons and electrons. However, based on the constraint on the extended γ rays given by another Fermi-LAT analysis, positrons from Geminga would be insufficient to account for the positron excess. Further robust analysis of Fermi-LAT data for the extended γ rays would be crucial to determine whether Geminga can explain the positron excess or not.     

Raman spectroscopy as a rapid screening method for ancient plain window glass

The aim of this paper is to highlight the potential of Raman spectroscopy as a fast screening method for large amounts of glass samples. Besides the dedicated research of specific glass collections during the last ten years, a broad corpus of archaeological window glass still needs to be investigated. For many sites, the amount of excavated glass artefacts is enormous and a selection of the most appropriate samples for chemical analysis is necessary. A classification can be made on the basis of the typical Raman signatures for the different kinds of glasses (alkali glass, high‐lime low‐alkali (HLLA) glass, Pb‐rich glass). Even in case of strong fluorescence, an uncomplicated treatment (normalisation) of the measured signals makes it possible to distinguish between the different types of glass. The preliminary screening of glass artefacts with Raman spectroscopy is a useful tool in the study of historical glass and can already answer some questions about provenance, period of production and authenticity of the glass samples. Copyright © 2010 John Wiley & Sons, Ltd.     

Characteristic features of thermoluminescence kinetics in dosimetric aluminum oxide crystals

We have studied the thermoluminescence curves in the 420 nm band (F centers) and the 330 nm band (F⁺ centers) within the temperature range of the dosimetric peak (T_max = 450 K) in anion-deficient aluminum oxide crystals. Assuming general-order kinetics, we have analyzed the thermoluminescence decay curves on the rising and falling sides of the dosimetric peak, in samples with different degrees of deep trap filling. We have established differences in the order of the kinetics within different temperature ranges of the dosimetric peak. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 187–190, March–April, 2006.     

Study on the optimization of the water Cherenkov detector array of the LHAASO project for surveying VHE gamma ray sources

It is prpopsed that a water Cherenkov detector array, LHAASO-WCDA, is to be built at Shangri-la, Yunnan Province, China. As one of the major components of the LHAASO project, the main purpose of it is to survey the northern sky for gamma ray sources in the energy range of 100 GeV-30 TeV. In order to design the water Cherenkov array efficiently to economize the budget, a Monte Carlo simulation is carried out. With the help of the simulation, the cost performance of different configurations of the array are obtained and compared with each other, serving as a guide for the more detailed design of the experiment in the next step.     

Magneto-optical properties of terbium glass

Dispersion of the Verdet Constant of Tb-glass is investigated.The cause of thisdispersion is dicussed by a comparison with the dispersion of refractive index.Relationship be-tween the Verdet constant and Tb~(3 ) concentration is summaried and can be used to estimatethe Verdet constant of Tb~(3 )-materials.