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。     

掺Dy,Tm和Mn的MgSO4磷光体的热释光发光谱研究

用高温固相法研制了MgSO₄:Dy,MgSO₄:Tm和MgSO₄:Mn热释光材料,并通过将MgSO₄:Dy和MgSO₄:Mn混合,以及MgSO₄:Tm和MgSO₄:Mn混合烧结得到了双掺杂样品MgSO₄:Dy,Mn,MgSO₄:Tm,Mn。分别测量了这两种样品在不同热处理温度下的三维发光谱。实验结果表明热处理温度为700℃时的样品,在测量加热过程中观察到Dy和Mn离子分别发光,但超过800℃后,Mn发光强度逐渐变弱,而Tm、Dy的高温发光峰逐渐变强,其它温度的发光峰受到抑制。这表明热释光材料中形成的缺陷复合体结构与热处理温度相关,随着热处理温度的升高,愈来愈多的Mn离子与稀土离子结合紧密,因此在热释光发光谱中清楚地观察到Mn离子对稀土离子的能量转移和对Tm、Dy低于400℃发光峰进行抑制的发光过程。     

Thermoluminescence response of CaS:Bi nanophosphor exposed to 200 MeV Ag ion beam

A study of the thermoluminescence (TL) parameters has been performed on swift heavy ion exposed Bi³⁺ doped CaS nanophosphors prepared by the chemical co-precipitation method. All the samples have been exposed to 200 MeV Ag⁺¹⁵ ions in a fluence range of 1 × 10¹²–1 × 10¹³ ions/cm². The prominent TL glow peak at 403 K (observed for the γ-irradiated sample) appeared at the same position in the 200 MeV Ag⁺¹⁵ ion beam irradiated samples, while the other peak at 466 K disappeared and the broad peak normally measured at 534 K split into two peaks at 535 K and 582 K for the Ag⁺¹⁵ ion beam irradiated samples. The effect of different Bi³⁺ concentration has been investigated and it was found that the maximum TL intensity was measured for the 0.08 mol% sample. The effect of different heating rates on the TL response has also been determined. The trapping parameters (i.e. activation energy, frequency factor, order of kinetic) of all the individual peaks of the glow curves have been analysed by using Chen’s formulae. The low fading and linear TL response in the range of 1 × 10¹²–1 × 10¹³ ions/cm² will be helpful to explore the potential use of this material for heavy ion dosimetry.     

Thermoluminescence as a new research tool for the evaluation of geothermal activity of the Kakkonda geothermal system, northeast Japan

The thermoluminescence glow-curve of quartz in volcanic and pyroclastic rocks of the Miocene and Quaternary in the Kakkonda geothermal field was divided into L (low), M (medium) and H (high) peaks in order of increasing temperature. Thermoluminescence emission is independent of stratigraphic boundaries but it is closely related to surface geothermal manifestations. Thermally stimulated processes of thermoluminescence caused by natural annealing occurred in the Quaternary after the eruption of the Tamagawa Welded Tuffs; radiation storage processes then began, as a consequence of the temperature drop. Thermoluminescence behavior indicates natural temperature manifestations, together with the paleo-temperature history.The H peak was thermally stable compared to the L and M peaks, and the area within which the relative intensity of the H peak is less than 5% coincides with the surface zone where dominant fluid flow is convective. In addition, L and M peaks indicate that a relatively low-temperature fluid mixes with the hot upflow around the western margin of the ascending flow zone.Thermoluminescence characteristics reflect paleo-temperature history and are related to geothermal fluid flow. Thermoluminescence is an effective exploration technique for evaluating natural temperature manifestations and subterranean heat flow in geothermal systems.     

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.     

Thermoluminescent properties of Mn-doped YAP synthesized by the solution combustion method

The work describes results of Mn-doped YAlO₃ (YAP) nanocrystalline materials synthesized by the solution combustion method using urea as a fuel. The materials were characterized by X-ray powder diffraction, scanning electron microscopy and luminescence techniques. The combustion synthesis method with codoping with Hf⁴⁺ ions allows to obtain highly efficient YAP:Mn²⁺ phosphor with negligible emission from Mn⁴⁺ ions that can be applicable for thermoluminescent dosimetry of ionizing radiation. Namely, the phosphor has a single dominating thermal glow peak at about 200 °C with the green emission near 530 nm related to Mn²⁺(Y) ions.     

Thermoluminescence studies of ultraviolet and gamma irradiated erbium(III)- and ytterbium(III)-doped gadolinium oxide phosphors

Present paper deals with the thermoluminescence (TL) properties of Gd₂O₃:Er³⁺, Yb³⁺ phosphor synthesized by a conventional solid state reaction method. The TL measurements were performed under UV and gamma irradiations. The structural and morphological analysis of the resulting phosphor was carried out by X-ray diffraction (XRD) study and field emission gun scanning electron microscopic (FEGSEM) technique. The functional group determination of prepared phosphor was carried out by Fourier transform infrared (FTIR) analysis. Elemental analysis was carried out by energy dispersive X-ray analysis. The particle size was determined by transmission electron microscopic (TEM) technique. For UV irradiation UV source providing 254 nm wavelength was used. Whereas Co⁶⁰ gamma source was used for gamma irradiation. The TL response of Gd₂O₃:Er³⁺, Yb³⁺ phosphor for two different radiations was compared and studied in detail. The process and possible mechanism for TL were investigated and discussed with the help of energy level models. The kinetic parameters such as order of kinetics, activation energy and frequency factors were evaluated by peak shape method and curve fitting technique. Effects of varying concentrations of Er³⁺ and Yb³⁺ was also investigated. The TL studies were further investigated by applying computerized glow curve deconvolution (CGCD).     

Thermoluminescence of alkali halides doped with alkaline earth impurities

Doping with alkaline earth impurities converts the alkali halides into very efficient phosphors. LiF doped with Mg is extensively used in radiation dosimetry. However, the phenomenon of thermoluminescence in these materials is far from clear. LiF-tld 100 is artificially separated from the rest of the alkali halide phosphors. The available experimental data are not fully utilised in building a model for thermoluminescence processes. In this review, thermoluminescence properties of LiF-tld 100 and other alkali halide phosphors are discussed. The comparative study which points out several common points could be useful in understanding thetl processes in these phosphors.     

Study on fine quartz pre-dose techniques

When using the pre-dose technique in ceramic dating,it is essential to add a calibration dose and to eliminate the background dose.For doing this measurement the sample requires multiple activation following multiple administration of a test dose to induce simulated “ancient” thermoluminescence(TL).However,the procedures introduce many factors that are difficultly corrected.This paper compares existing two kinds of measurement procedures and proposes a new procedure involving single activation following a single test dose administration.AN experiment using the single activation procedure is carried out with natural fine quartz where the results obtained exhibit only 0.07 relative error.It appears that this new procedure increases the precision of the ancient TL measurement by about 0.04 and 0.11 over those of existing two kinds of procedures.In addition this method can give realistic values in TL dating for relatively “young” samples aged tens to hundreds of yesrs where the standard high temperature TL method is relatively insensitive.