Characterization and thermoluminescence behavior of beta irradiated NaBaBO3 phosphor synthesized by combustion method

NaBaBO₃ host material was synthesized using the combustion method. In order to optimize the performance of the material, effects of sintering temperatures varying from 600° to 1000?°C were investigated. The sintering temperature and dwell time were found to have pronounced effects on the pure NaBaBO₃ material. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to confirm the phase formation and examine the surface morphology of the prepared powder material, respectively. TL behavior of NaBaBO₃ was studied at various beta doses. It is seen that the sample exhibits well resolved TL glow peak at a peak temperature about 175?°C and corresponding TL intensity increases with the increasing beta dose. However, TL glow peak slightly shifts to lower temperature with the increasing beta dose level. This is the first TL report of a phosphor with a NaBaBO₃ host. The TL kinetic parameters were estimated by the peak shape (PS) method and CGCD software. TL glow curves of NaBaBO₃ consist of several traps and exhibited second order kinetics. A possible TL mechanism was also discussed using the energy level model. The obtained results can provide valuable knowledge related to the investigation of the intrinsic nature characteristics of NaBaBO₃ in research fields pertaining to dosimetry.     

Optically stimulated luminescence (OSL) of Lu2SiO5:Ce powder: A preliminary study

Optically stimulated luminescence (OSL) of Lu₂SiO₅:Ce powder (Phosphor Technology Ltd., UK) has been measured by Risø TL/OSL Reader (TL-DA-15). Upon blue photon stimulation (λ_ex ∼470 nm) the material shows strong OSL signal that can detect β-irradiation right up to the dose of ∼0.2 Gy.A brief discussion on this finding is presented by comparing the thermoluminescence of the system with and without optical stimulation. The two key important parameters namely, trap-depth (E) and frequency factor (s) of the main peaks that occur at 85 and 232 °C are determined.     

Thermal quenching of thermoluminescence in quartz samples of various origin

The effect of thermal quenching stands among the most important properties in the thermoluminescence (TL) of quartz on which many applications of TL are based. Since the quartz samples used in various applications are all of different origin it is useful to investigate whether the values of the thermal quenching parameters, i.e. the activation energy for thermal quenching W and a parameter C which describes the ratio of non-radiative to radiative luminescence transitions, evaluated mainly in specific quartz samples can be extrapolated to quartz samples of unknown origin as well as to quartz samples which are annealed at high temperatures. In the present work the TL glow curve of a series of un-annealed and annealed natural and synthetic quartz samples were studied as a function of the heating rate between 0.25 K/s and 16 K/s. Using an indirect fitting method it was found that the thermal quenching parameters W and C in most of the quartz samples are very similar to the values accepted in the literature. Furthermore, in some cases the thermal quenching parameters W and C are not the same for all TL glow-peaks in the same glow-curve. Finally, the strong external treatment of annealing the quartz samples at very high temperature can also influence at least one of the thermal quenching parameters.     

从α剂量识别陶器的人工辐照

为识别陶器有否经过人工辐照，本文用细粒样品的“细粒技术”和“前剂量技术”分别测定一件陶器的古剂量。如果细粒技术测量得到的古剂量大于前剂理技术测量得到的古剂量，那么，其差额部分就是α剂量，有α成分的古剂量是天然辐照的，那么这件陶器就是古代的；如果两个古剂量近似相等，说明古剂量中没有α成分，没有α成分的古剂量是人工辐照的，那么这件陶器就是现代的。     

6MV X射线能谱的实验测定

用穿透系数数值分析的叠代最小二乘法对稳态加速器的Ｘ射线能谱进行了实验测定，编写了叠代最小二乘法的计算程序。     

Absorbed dose estimation using LET dependence in glow curve of thermoluminescent phosphor Li3B7O12:Cu in therapeutic carbon beams

A high temperature ratio (HTR) method has been proposed to correct the linear energy transfer (LET) dependence of thermoluminescent (TL) efficiency. To realize the use of the slab-type thermoluminescence detector (TLD) that based on the phosphor Li₃B₇O₁₂:Cu for heavy charged particle beam, the HTR method has been considered. To improve the reproducibility of HTR, the slow heating rate method is introduced in this report and the coefficient variations of HTR decreased from 10%–20% to 8%. The relation between TL-efficiency, HTR, and LET for Li₃B₇O₁₂:Cu was manifested and the TL-efficiency as a function of HTR was derived in an attempt to measure the absorbed dose without LET information. The feasibility of the HTR method in therapeutic carbon beams was evaluated by comparing the dose estimated by Li₃B₇O₁₂:Cu and by an ionization chamber. The accuracy of dose estimation in carbon beams was improved by using the HTR method, but there is room for further improvement. The use of Li₃B₇O₁₂:Cu in heavy charged particle beams can be materialized with further improvement of HTR sensitivity.     

热释光氡子体个体α剂量计的研制与现场试验

有源式热释光氡、子体个体α剂量计现已研制成功。该剂量计采用超薄型CaSO_4·Tm热释光片,对α辐射的探测灵敏度高于其它氡子体剂量计,而对γ辐射的响应仅为0.8(读数/mR)。因此,探测下限低至1.04μJ·m~(-3)·h(0.05WLh) (γ本底1mR/h;取样周期6h)。取样头中装有三片CaSO_4·Tm,氡、子体暴露量可分别测定。取样泵中虽未装自动调流装置,但流率-阻力特性良好。自1981年以来,该剂量计在实验室和现场经过一系列试验,证明性能良好。本文着重概述了该剂量计的原理,特点及现场试验结果。