SYSTEMATIC ERROR FROM Th/U RATIO IN LUMINESCENCE AND ESR DATING

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用厚源α计数测定TL和ESR年代中的钍、铀年剂量

本文叙述了用厚源α计数技术测定TL和ESR年代中钍系和铀系年剂量的原理和方法。该方法主要优点是测定α年剂量时,可将计数率直接代入生龄公式,不需要计算钍、铀含量和剂量率转换因子。但在估算β和γ年剂量时,必须假定样品中的钍、铀放射性是相同的,或者用“对”技术来确定钍、铀含量。     

表面TLD法测定瓷器的年剂量

用CaSO4:Tm超薄型热释光剂量片放在瓷器无釉或器物内部去釉后的部位，用表面TLD法测量瓷器样品中的年剂量，与α计数法及内部TLD法测得的瓷器年剂量值比较的结果表明，表面TLD技术能用于瓷器年剂量的测定，有助于提高TL测定瓷器年代的准确性，同样也适用于TL测定陶器的年代。     

年代测定中的β剂量学问题

本文描述了热释光(TL)和电子自旋共振(ESR)测年方法对剂量标定的若干要求。研究了~(90)Sr、~(90)Y在石英中各自的剂量占总剂量的百分比随深度的变化及该源照射不同大小颗粒石英时的平均剂量与表面(或参考点)剂量的关系。指出了忽略这一因素时所带来的误差的大小。     

ELECTRON SPIN RESONANCE DATING FOR THE AGE OF PEKING-MAN, LOC.1, ZHOUKOUDIAN, BEIJING

In this paper, we used ESR dating method to measure the accumulative dose of the fossil teeth samples, which are contemporaneous with the Peking-Man. The internal annual dose rate of samples are got by neutron activation analysis and the environmental annual dose rate by highly sensitive TL dosimeters to be embedded in cave deposits in the site. The results of ESR dating are corresponded with the dating results obtained by U-series, FT, TL and paleomagnetic stratigraphical methods on the 3rd, 4th, 7th and 10th layers. Calculation of using different models, the close-equilibrium model, the linear uranium accumulation model and radon loss-linear uranium accumulation model, for travertine, deer teeth and rhinoceros tooth, we obtained the age of the First Peking- Man in the nth layer is 578 ka and gave ages of other layers, from the 1st to the 13th layer in Peking- Man site.     

石英热释光年代测定中测量条件优化研究

本文基于石英热释光特性分析,通过实验方法分析石英在不同辐照剂量下375 ℃热释光峰的最佳预热温度和校正石英热释光灵敏度变化的最佳试验剂量,并依据实验结果对常规流程加以改进。最终,验证基于最优测量参数的改进流程对等效剂量测量准确度的提升。实验结果表明,若等效剂量较小,325 ℃热释光峰的信号较弱,选取较低的预热温度即可压制其对375 ℃热释光峰的影响。若等效剂量较大,则石英测片应先通过预热温度测试,根据再生剂量和试验剂量的最优预热温度进行等效剂量测量。石英测片再生剂量的取值处于0～1 000 Gy范围内时,200 Gy的试验剂量能对石英测片的热灵敏度变化起到校正作用,且10次重复测量结果的相对偏差小于5%。通过上述最优预热温度和试验剂量设置,分别降低325 ℃热释光峰残余信号干扰和校正石英热灵敏度变化。改进流程下400 Gy和700 Gy等效剂量测量值的相对偏差由常规流程的14.74%～47.15%和33.47%～197.71%均降低到±4%以内。本文为石英的375 ℃热释光峰年代测定准确度和年代测定范围的提升提供了重要参考依据。     

Track interaction in gamma- and charged-particle-irradiatedthermoluminescence dosimeters

The growth of thermoluminescence (TL) and optical absorption (OA) with absorbed dose was examined in LiF doped with Mg, as functions of both the linear energy transfer (LET) of the incident radiation and the impurity content of the samples. In addition, the TL growth curves were examined as a function of the heating rate during readout. The growth of TL as a function of dose is basically linear-supralinear-sublinear, but the precise character of the dose response function varies with the LET of irradiation, the Mg impurity content of the sample, and the heating rate during TL readout. the OA dose response is always linear-sublinear over the same dose ranges, even for those defect centers that are known to be involved in the TL process. The data indicate that the mechanisms responsible for the supralinear nature of the TL growth are operative during the TL readout phase rather than the absorption phase. A mathematical model is presented that qualitatively describes the results. The model is conceptually the same as the so-called track interaction model for high-LET irradiation, but the extension presented here makes it applicable to gamma-irradiated samples also     

热释光断代的进展

本文评述了热释光断代的近况。它们是:磷光体的热释光性质;关于发光中心;辐射剂量学,综述了五种测定年辐射剂量的方法,同时也讨论另两种测定氡逸散的方法;各种不同类型标本中累积辐射剂量的测定;热释光测量中的样品制备;辐射源及校正及其在热释光断代中的应用;测量热释光的装置。     

Natural radioactive environment of urban soils in Shihezi, China

Radionuclides, such as ~(238)U,~(232)Th and ~(40)K, can be found in urban soil. To evaluate the natural radioactivity in the environment, soil samples were collected form Shihezi city and radioisotope concentrations were determined by X-ray fluorescence. The dose rate of urban soil (mGy per year, mGy/a) was calculated. The results indicate that the U, Th and K concentrations of the urban soils were, respectively, 1.2-3.2 mg/kg, 6.4-12.3 mg/kg and 2.05%-2.24%, with the mean values of 2.47 mg/kg, 10.47 mg/kg and 2.16 %. Dose rates of urban soils were 10.04-19.55 mGy/a with the mean value of 16.31 mGy/a. This dose rate is the perfect and maximum value of natural radiation in soil and different with the air absorbed dose rate from terrestrial γ-rays. The mean value of air absorbed dose rate was about 57.42 nGy/h. The annual effective dose rate in air was about 0.07 mSv/a and the average value of Ra_(eq) in urban soil was 120.37 Bq/kg. The relative contribution of a particle to the dose rate is higher than that derived from β- and γ-rays in the urban soils.     

江苏省城市放废库辐射环境监测水平研究北大核心CSCD

随着核技术在各领域的广泛应用,辐射环境的安全受到越来越多的重视。以江苏省城市放废库为研究对象,从2015年起连续对放废库进行辐射环境监测6年。对放废库周围的γ辐射空气吸收剂量率,水源水中总α、总β以及土壤中放射性核素进行了监测,并对辐射监测结果进行了分析。研究结果表明γ辐射空气吸收剂量率敏感点范围为59.0~96.5 nGy/h,源库四周范围为81.92~103.32 nGy/h;水源的总α和总β范围分别为0.90×10^(-2)~5.87×10^(-2)Bq/L和3.00×10^(-2)~16.00×10^(-2)Bq/L。γ辐射空气吸收剂量率的变化主要与源库的距离和废源的管理有关;水体中放射性水平变化主要与年降水量有关;土壤中核素的变化主要与放射性气溶胶有关。所有变化均在本底范围内涨落,对环境几乎没有影响,可以确保辐射环境安全。     

青岛市地表天然放射性水平及其主控因素特征

通过对青岛市1 500 km2范围内大密度土壤放射性核素(238U、232Th和40K)和地表γ辐射测量,系统深入地研究了其放射性特征、分布规律及其影响因素.结果表明,青岛市土壤中核素232Th和40K的放射性比活度偏高,而2388U偏低.地表γ辐射吸收剂量率(平均值91.87 nGy· h-1)略高于全国和世界平均值,研究发现地表93.14％的γ辐射来自地面放射性核素238U、232Th和40K的γ辐射,其中232Th和40K的贡献占81.21％,是主要的贡献者.地质背景是影响地面γ辐射吸收剂量率的主要因素,燕山期各类花岗岩是导致青岛市区—王哥庄一带γ辐射吸收剂量率偏高的主要原因;同时环境因素(路面材料、地貌景观)对地表γ辐射吸收剂量率也存在一定影响.虽然研究区的γ辐射吸收剂量率较高,但其年有效剂量(0.56 mSv)远低于公众照射年剂量当量限值1.0 mSv,人居环境基本不受影响.     

TL和ESR年代测定法中年剂量计算模式的讨论

本文讨论了用封闭平衡模式、氡逸散模式、铀系不平衡模式和铀线性积累模式计算年剂量的方法及其地质意义。     

富石英粉体热释光陷阱参数对等效剂量的影响

本文使用RGD-3B型热释光仪,获得富石英粉体的发光曲线。在5 K/s的升温速率下,发光曲线呈现448、551、654、756 K 4个峰。用多种升温速率法确定4个发光峰的激活能、频率因子和陷阱电子寿命。在一定激活能范围（0.7～1.86 eV）内,随激活能的增加,等效剂量呈指数增大。温度在548～608 K,等效剂量从54 Gy增至485 Gy;在608～748 K,等效剂量随温度的升高变化不大,在531 Gy附近波动。     

“非剂量”热释光断代

本文叙述了一个“非剂量”热释光断代方法。在这个方法中,总热释光和年热释光分别用考古样品中的天然矿物和人造热释光材料测定,并用热释光直接估算年龄。用本方法测定了28个考古样品,结果表明,这些年龄与用剂量法测得的热释光年龄一致,并具有误差降低和不需要刻度放射源的优点。     

Study on TL and OSL characteristics of indigenously developed CaF2:Mn phosphor

CaF₂:Mn phosphor is known for its high thermoluminescent sensitivity and dose linearity up to few kGy. In the present study CaF₂ phosphor with different concentration of Mn dopant was prepared and was characterized through different techniques. The phosphor was prepared through chemical root using CaCO₃, HF acid and MnCl₂ as raw materials following co-precipitation method. TL sensitivity of the prepared phosphor was compared with other well established phosphors used for radiation dosimetry. It was found that the TL sensitivity is higher by a factor of 10 with respect to LiF:Mg, Ti, TLD-100 and half to that of CaSO₄:Dy (0.05 mol%) phosphor. X-ray diffraction, TL emission spectrum and ESR spectrum taken of the prepared phosphor confirms the crystal structure, Mn²⁺ emission and incorporation Mn in the crystal, respectively. No significant fading of the dosimetric peak was observed of the prepared phosphor for a storage period of 45 days. The dose linearity of the phosphor was found to be in the range of 50 Gy-3 kGy within an uncertainty of about 10%. An attempt was made to determine the kinetic parameters of TL glow curve and the parameters related to optically stimulated luminescence. In view of its long range of dose linearity, it can be used for the dosimetry of commercial irradiator generally used for the irradiation of food and grains in our country.     

不同厚度石英对α射线的热释光响应

实验研究了不同厚度石英对α射线的热释光（TL）响应。使用经2.64Gyα辐照过的石英,在相同面积的铝片上制作成不同厚度的石英样品,用热释光剂量仪读取峰面积积分,最终得出不同厚度的石英随辐照剂量变化的热释光响应。     

Synergistic extraction of U（VI） and Th（IV） from nitric acid media with HBMPPT and TBP in toluene

The sysnergistic extraction of U(VI)and Th(IV) from nitric acid solution by HBMPPT(4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) and TBP( tributylphosphate)in toluene was studied.The extraction ability of HBMPPT for U(VI) and Th(IV) was not so high.but when a little TBP was added in,the ability to extract U(VI) and Th(IV) was improved.The extracted complexes may be presented as UO2NO3.BMPPT.TBP and UO2(BMPPT)2.TBP for U(VI).and Th(NO3)3.BMPPT.TBP and Th(NO3)2(BMPPT)2.TBP for Th(IV),respectively,in the synergistic extraction system.The synergistic effect of HBMPPT and TBP makes the separation cofeeicient of U(VI)/Th (IV) or U(VI)/Eu(Ⅲ) reach a high value.     

热释光方法在环境剂量监测中的应用

天然热释光量和年剂量是热释光断代工作中两个重要参数，它们代表着标本周边环境的放射性辐射水平。实验数据表明，环境辐射水平受到基底岩性的控制影响。经过长期改造，地表环境辐射水平将逐步减弱并匀化。     

铀系不平衡样品年剂量的确定

利用堆中子活化分析法测定样品中＾２３８Ｕ的含量，利用纯猪半导体探测器γ谱仪测定样品中＾２２６Ｒａ含量，利用α计数仪或γ谱仪测定＾２２２Ｒｎ的逃逸系数，最后采用计算法得到铀系不平衡样品的年剂量。