加速器质谱测量93Zr的刻度研究

A method of determination for ⁹³Zr/⁹²Zr ratio by multi-collector inductively plasma mass spectrometry (MC-ICP-MS) was described in this paper. A ⁹³Zr/⁹²Zr ratio of (2.75±0.07)×10^－5 was obtained in the original sample for AMS measurement and its relative standard error was 2.5%. Considered the contribute of above-thermal neutron, a calculated ⁹³Zr/⁹²Zr ratio of 2.56×10^－5 was obtained and it was according with measurement of the result. The results showed that it can be used for AMS measurement standards sample preparation. A series 93Zr standards sample for AMS measurement were diluted by irradiated sample with enriched 92Zr.     

236U及其加速器质谱测量的进展

236U在自然界中的含量极微,所以,236U含量水平的提高可以被用作人类从事铀辐照实验的指纹。20世纪50年代的核活动开始排放人造236U到环境中,现在环境中可移动的236U库中99％以上是人为产生的,主要是由核活动和核设施,特别是核燃料后处理厂释放出来。     

151Sm半衰期及其γ射线强度测定

151Sm为裂变产物核素,有较高的裂变产额。本工作开展对151Sm半衰期的精确测定。151Sm利用反应堆照射通过150Sm（n,γ）反应得到。照射后经过冷却后利用热电离质谱对151Sm／150Sm原子比进行了测定,测定结果为151Sm／150Sm原子比=（3．750±0．002）×10^-3.     

79Se—AMS测量样品的化学形式选择及其制备方法

中国原子能科学研究院的AMS小组在原蒋菘生、何明等对79Se—AMS测量的基础上,发展了基于SeO2-分子负离子引出形式的79Se—AMS测量方法,测量灵敏度由原来的3．0×10^-9提高到好于1．0×10^-12。     

裂变产物核136Sn原子数的γ能谱法测定

裂变产物136Sn是一种长寿命纯β放射性核素,半衰期为（2．35±0．07）×10^5a。该核素是核工程对环境长期污染的重要指示核素,对于它的超高灵敏测量将为监测环境中的核污染提供重要的信息。     

加速器质谱测量136Sn的负离子引出实验研究

许多核素的同量异位素不能形成负离子或形成的负离子不稳定,可借助于此来有效消除同量异位素干扰,这是串列AMS的优点之一。此外,AMS测量中选用某种化合物形式引出相应负离子时,其干扰核素不能形成负离子或者束流很小,这样,即可在离子源处压低同量异位素的干扰,从而可提高测量灵敏度。因此,样品化学形式及引出负离子的选择在AMS测量中是非常重要的。     

AMS测量用HfF4样品的干法制备

在HfF4样品的测量中，样品中氧含量越高，HfF5负离子的引出束流则越小。而且如果样品中含有氧，则易形成类似WF4^18OH^-的离子引出形式，起不到压低W的作用。因此，要求将样品制成纯的HfF4形式，并尽可能降低样品中氧的含量。通常制取氟化物时采用液相反应（称之为“湿法”），“湿法”制备遇到的主要问题是氟化物中的氧含量高。     

液闪法测定~(151)Sm的半衰期

采用液闪β放射性计数法(LSC)测量中国原子能科学研究院重水堆上辐照后样品中151Sm的活度,用表面热电离质谱(TIMS)和电感耦合等离子质谱仪(ICP-AES)法结合测得样品中151Sm的原子个数,计算得到151Sm半衰期.在LSC实验测量前的γ谱和β谱测量表明,干扰核素152Eu、154Eu、40K等对151Sm的LSC测量影响可忽略.用14C的效率示踪-液闪法测定151Sm的比活度为(603.3±15.1)Bq/mg,相对误差为2.5%,原子个数测量结果为2.769×1012个,求得151Sm半衰期为(96.7±2.8)a,相对误差为2.9%.     

79SeAMS测量实验室标准中79Se/78Se比值

Using liquid scintillation counting (LSC) to determine the ratio of ⁷⁹Se/⁷⁸Se in the irradiated sample was reported. Firstly, the γ and β spectrum of irradiated sample was measured to find out the interferefering nuclide. Then, the irradiated sample was heated up to remove the interferefering nuclide from the sample as much as possible. At last, the activity ⁷⁹Se was determined by LSC, and the ratio of ⁷⁹Se/⁷⁸Se was determined to be (5.44±0.23)×10^－5. It provides reliable standard sample for AMS measurement.     

长寿命裂变产物126Sn活度和原子数的γ能谱法测定

By using HPGe γ-ray spectrometry, the activity of the long-lived fission product ¹²⁶Sn was measured. The number of ¹²⁶Sn atoms and the isotopic abundance of 126Sn/Sn were calculated based on the half-life value of 2.35×10⁵ a. The result of the isotopic abundance, (1.037±0.044)×10^－8, is consistent with the results measured by the accelerator mass spectrometry (AMS) within uncertainty limits, that confirms our procedures in the measurement of ¹²⁶Sn by AMS and lays a foundation for the AMS measurement of ¹²⁶Sn at much lower levels.