液闪测量低能β核素的放射性活度

为了测量缺乏标准溶液的低能弱β放射性样品的活度,采用分布在低能区(0~150 keV)的6种β核素(3H、241Pu、106Ru、63Ni、151Sm和14C)的标准溶液刻度低本底液闪谱仪(Tricarb-3170)的探测效率。在此基础上,拟合出探测效率随淬灭指数和核素平均能量变化的三维曲面。对影响液闪测量的主要因素,如闪烁液、淬灭剂、介质、样品瓶、体积等进行了研究,确定了最佳测量条件。该方法刻度了仪器在整个低能区的探测效率,适用于所有低能β核素活度的快速准确测定。     

液闪计数测α核素技术的一些进展

本文简述用脉冲波形甄别原理在液闪计数器上测定α核素的方法，介绍了一种选择性萃取闪烁液的组分和一个实用的α计数样器的制备程序。并根据１９９４年国际液闪会议所报道的资料，展望了液闪计数在环境氏水平α、β核素分析中的应用前景。     

液闪测量的影响因素研究

在过去几十年中,液闪分析技术一直是放射性核素,特别是低能B核素测量的最流行工具。但人们对日常工作中液闪分析的影响因素却往往缺乏足够的重视。本工作从液闪瓶、闪烁液、淬灭剂、计数体积、样品介质等方面对影响因素进行了研究,指出了液闪测量中应该意的几个问题。     

样品活度、浓度、容积对液闪计数效率的影响

液体闪烁测量法是近年来发展很快的一种软β射线测量法,特别在生物医学等自然科学领域中应用更为广泛,这是因为有些重要元素如碳和氢的主要放射性同位素只产生软β射线,大量示踪工作要用这些同位素进行。本文通过液体闪烁测量法,在放射性比度和闪烁系统条件相同时,对不同活度、浓度、容积的~3H-四环素样品测量结果的比较,分析这些因素对样品计数率的影响,以期对未知样品测量作相应的校正。     

1220 Quantulus液闪谱仪测量3H计数效率的刻度

介绍了1220Quantulus液闪谱仪测量^3H计数效率的刻度方法。实际结果表明，用商用猝灭校正源来刻度仪器计数效率，首先应检验对实验被测样品的适用性，否则会使样品测量值有较大误差；对于一般的^3H常规监测，样品制备程序相同，猝灭情况变化不大，猝灭系数SQP（E）在711－732之间波动，因而可以用被测样品的空白材料无氚水作为猝灭剂来配制猝灭系列源，并用它制作的校正曲线来刻度仪器计数效率，或者简单地用与被测样品猝灭情况相近的源作为标准来确定计数效率。     

液闪α能谱法绝对测量铀溶液中的铀含量

液闪α能谱法是一种将液闪法和α能谱法的优点有机结合在一起对α核素进行绝对测量的新方法。本工作用该方法分析了简单铀溶液样品中的铀含量（质量浓度）,分析结果与标准溶液标称值符合良好。该方法有望用于分析环境样品中的铀含量。     

用液闪直接测量核设施周围环境中的氚

某些核设施运行时会释放氚,从而引起周围环境中氚活度浓度水平的变化。对核设施周边区域空气、地下水、雨水和海水样品中的氚分别用内标准法(简称“内标法”)和外标准淬灭指示参数法(简称“外标法”)进行了液闪测量。两种标准方法测量数据的相对偏差在-4.0%～4.0%。根据内标法的探测效率与仪器给出的淬灭指示参数制作了4种环境水样的淬灭校正曲线。在环境样品测量中,内标法和外标法的探测效率最大差值约为1.6%,痕量¹⁴C和其它β放射性核素对³H的计数率影响可忽略。对探测效率为21.5%～24.5%无严重淬灭的样品,用液闪直接测量并根据外标法的淬灭校正曲线计算氚活度浓度,相对偏差在-6.35%～4.41%,基本可满足核设施氚常规监测的要求。     

用恒流技术改进液闪中电荷灵敏放大器的性能

在液闪电子线路中,有各种各样的电荷恒流技术,本文重点强调恒流、电荷技术及在液闪中的应用。     

液闪TDCR测量装置研制

介绍了新建液闪活度绝对测量装置,该装置应用液闪三管两管符合比（TDCR）测量原理对β放射性核素活度进行测量。装置由3个光电倍增管及自制的散焦分压线路组成。通过改变光电倍增管的聚焦来改变探测效率,测量了³H放射源活度并进行了不确定度分析及讨论,TDCR测量结果与标定值在0.9%内符合,合成标准不确定度为0.6%（k=1）。     

用直接液闪法测定尿氚浓度

本文介绍了液闪直接测定尿氚浓度的方法。研究了采样器皿,存放方式和存放时间对测量结果的影响,同时还对直接测量法和氧化蒸馏法进行了比较。结果表明,尿氚直接测量去经济,简便,可满足核电站辐射工作人员尿氚浓度测定的要求;与氧化蒸馏法测定结果比较没有明显差异。     

液闪法提高~(32)P计数效率的研究

对 32 P的切仑科夫计数法及液闪测量作了比较 ,同时对于不同样品瓶和闪烁液对 32 P计数效率的影响进行了实验比较 ,指出提高 32 P测量效率的途径     

Determination of the Be half-life by multicollector ICP-MS and liquid scintillation counting

A new method was designed and used for determining the half-life of the isotope ¹⁰Be. The method is based on (1) accurate ¹⁰Be/⁹Be measurements of ⁹Be-spiked solutions of a ¹⁰Be-rich master solution using multicollector ICP mass spectrometry (MC-ICP-MS) and (2) liquid scintillation counting (LSC) using the CIEMAT/NIST method for determining the activity concentrations of the solutions whose ¹⁰Be concentrations were determined by mass spectrometry. Important requirements for the success of this approach (a) was the previous coating of glass ampoules filled for counting experiments with ⁹Be, thereby reducing the risk of the adsorptive loss of ¹⁰Be; (b) the removal of Boron from solutions to be measured by MC-ICP-MS by cation chromatography without the introduction of mass fractionation and (c) the accurate determination of the mass bias of ¹⁰Be/⁹Be measurements by ICP-MS which are always affected by the space-charge effect. The mass bias factor was determined to be 1.1862 ± 0.071 for ¹⁰Be/⁹Be from careful fitting and error propagation of ratios of measured Li, B, Si, Cr, Fe, Cu, Sr, Nd, Hf, Tl and U standard solutions of known composition under the same measurement conditions. Employing this factor, an absolute ¹⁰Be/⁹Be ratio of 1.464 ± 0.014 was determined for a first dilution of the ¹⁰Be-rich master solution. This solution is now available as an absolute Be ratio standard in AMS measurements. Finally, a half-life of (1.386 ± 0.016) My (standard uncertainty) was calculated. This value is much more precise than previous estimates and was derived from a fully independent set of experiments. In a parallel, fully independent study using the same master solution, Korschinek et al. [35] have determined a half-life of (1.388 ± 0.018) My. The combined half-life and uncertainty amounts to (1.387 ± 0.012) My. We suggest the use of this value in nuclear studies and in studies that make use of cosmogenic ¹⁰Be in environmental and geologic samples.     

A new value for the half-life of Be by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting

The importance of ¹⁰Be in different applications of accelerator mass spectrometry (AMS) is well-known. In this context the half-life of ¹⁰Be has a crucial impact, and an accurate and precise determination of the half-life is a prerequisite for many of the applications of ¹⁰Be in cosmic-ray and earth science research. Recently, the value of the ¹⁰Be half-life has been the centre of much debate. In order to overcome uncertainties inherent in previous determinations, we introduced a new method of high accuracy and precision. An aliquot of our highly enriched ¹⁰Be master solution was serially diluted with increasing well-known masses of ⁹Be. We then determined the initial ¹⁰Be concentration by least square fit to the series of measurements of the resultant ¹⁰Be/⁹Be ratio. In order to minimize uncertainties because of mass bias which plague other low-energy mass spectrometric methods, we used for the first time Heavy-Ion Elastic Recoil Detection (HI-ERD) for the determination of the ¹⁰Be/⁹Be isotopic ratios, a technique which does not suffer from difficult to control mass fractionation. The specific activity of the master solution was measured by means of accurate liquid scintillation counting (LSC). The resultant combination of the ¹⁰Be concentration and activity yields a ¹⁰Be half-life of T_1/2 = 1.388 ± 0.018 (1 s, 1.30%) Ma. In a parallel but independent study (Chmeleff et al. [11]), found a value of 1.386 ± 0.016 (1.15%) Ma. Our recommended weighted mean and mean standard error for the new value for ¹⁰Be half-life based on these two independent measurements is 1.387 ± 0.012 (0.87%) Ma.     

用切伦科夫计数法确定破损元件组件

本文介绍了切伦科夫计数原理，分析了反应堆冷却剂中活化产物，裂变产物的放射性特性；讨论了用切伦科夫计数确定反应堆破损元件组件的可行性。     

2,6-二甲基吡啶萃取-液闪法测定后处理厂中的~(99)Tc

研究了2,6-二甲基吡啶萃取分离-液体闪烁法测定后处理厂工艺料液中99 Tc的分析方法。进行了铀、镎、钚、裂片元素对99 Tc测定的干扰与消除实验,对分离条件、液闪测量条件进行了优化。在选定条件下对模拟样品进行分析,精密度(sr)优于5%(n=6),99 Tc回收率为95%~105%。