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1.
The determination of uranium isotopic composition in trace samples is important in different fields. A new measurement method that uses an accelerator mass spectrometry (AMS) technique has been developed for the analysis of uranium isotopic ratios in ultra-trace uranium samples at the China Institute of Atomic Energy. As result, about 5-nanogram level uranium samples analyzed with AMS is achieved.  相似文献   
2.
The rare isotope 236U has a half-life of 2.342(3)×107 years,and is produced principally by thermal neutron capture on 235U.The isotopic atom ratio of 236U/238U depends on the integral thermal neutron flux received by the material of interest.236U is potentially useful as a fingerprint for indicating the presence of neutron-irradiated uranium usually originating from nuclear activity.By extracting negative molecular ion UO- from the uranium oxide target,simulating the 236U16O- beam transport with 238U16O- an...  相似文献   
3.
The rare isotope ^236U has a half-life of 2.342(3)×107 years, and is produced principally by thermal neutron capture on ^235U. The isotopic atom ratio of ^236U/^238U depends on the integral thermal neutron flux received by the material of interest. ^236U is potentially useful as a "fingerprint" for indicating the presence of neutron-irradiated uranium usually originating from nuclear activity. By extracting negative molecular ion UO^- from the uranium oxide target, simulating the ^236U^16O^- beam transport with ^238U^16O^- and ^208Pb2^16O^- pilot molecular ion beam, transporting the ^236U-containing ion beam with a high resolution injection magnet analyzer and electrostatic analyzer system, and finally identifying and detecting ^236U with a time-of-flight detector (TOF), a method for AMS (Accelerator Mass Spectrometry) measurement of ^236U was established on the HI-13 Accelerator AMS system at China Institute of Atomic Energy.  相似文献   
4.
王伟  李朝历  何明  武绍勇  姜山 《中国物理 C》2008,32(Z2):205-209
A new method for measuring selenium-79 with AMS, which is based on extracting molecular negative ions, is described in this paper. According to the experimental results, the extraction ion form SeO2 could depress the interference of Bromine-79 as much as 5 order levels, that is to say, the background of 79Br can be deducted to 79Br/Se≈10-10. By the way, the chemical form of sample and preparation flow was also developed. Finally, three 79Se AMS calibration standard samples with theoretical 79Se/Se ratios of 5.06×10-7, 6.87×10-8, 5.40×10-10 were obtained and the method of 79Se measurement was set up, which actualized transmission and detection of 79Se. By using our Bragg curve detector, the two isobars 79Br and 79Se could be partly identified to a certain extent and 79Se can be identified from 79Br about 1 order level. AMS measurements of the three calibration standard samples above were performed and good linearity was obtained. The sensitivity of the measurement is (5.16±1.80)×10-11.  相似文献   
5.
Loess is the most important and the most typical continental classic sediments of Quaternary. So the measurement of In-situ produced cosmogenic 10Be is expected to be used for the Loess stratigraphic age. But the production rate of In-situ produced cosmogenic 10Be in Loess quartz is very low. It requires very high sensitivity and accuracy of measurement. This work has measured the concentrations of 10Be of two layers in Loess section of Luochuan including L8, L9 and the concentrations of 10Be in (of) blank sample with the HI-13 AMS system at China Insitute of Atomic Energy(CIAE), then calculated the content of 10Be in loess quartz for each layer. The ratio of 10Be/9Be was found in the range of 10-13. The background of 10Be/9Be was about 3×10-14.  相似文献   
6.
AMS测量中同量异位素的鉴别方法   总被引:2,自引:0,他引:2  
在加速器质谱测量中,存在同位素和同量异位素的干扰.排除同位素的干扰是开展超微量核素分析的重要课题之一.主要介绍了加速器质谱测量中同量异位素的几种鉴别、排除方法,以及这些方法的原理、发展及应用. There are interference of isotopes and isobars in accelerator mass spectrometry (AMS) measurements. Eliminating the isobaric interference is the important aspect in AMS measurements. Several methods of isobaric identification in AMS measurements are discussed in this paper. Principles, developments and applications of these methods are also introduced.  相似文献   
7.
26Al是一个在多个学科都非常有意义的放射性核素。主要介绍了国内外在利用加速器质谱技术测量26Al时所开展的各种测量方法、各自的优缺点和测量灵敏度,并介绍了目前利用^26Al在地球科学、生物医学、核物理以及天体物理等诸多方面的应用研究工作。  相似文献   
8.
自然界样品中~(36)Cl的加速器质谱法测定   总被引:2,自引:0,他引:2  
描述基于中国原子能科学研究院串列加速器建立的加速器质谱方法,在我国首次测定了自然界样品中的(36)Cl,测定的(36)Cl/Cl比值灵敏度为3×10-15,所测定的自然界环境样品采自东北连山关铀矿区地下水和矿石、柴达木盆地朵斯勒湖石盐以及河北平原地下水,测定样品中36Cl/Cl比值范围为10-12至10-14。  相似文献   
9.
182Hf的半衰期为(8.90±0.09)Ma, 是一个接近灭绝的放射性核素. 超新星爆炸是自然界中已知的惟一能产生182Hf的途径. 因此182Hf是研究近1亿年来在地球附近可能发生的超新星事件的理想核素. 另外, 182Hf是核工程中特别感兴趣的一个长寿命放射性核素. 精确测量超痕量的182Hf对反应堆的设计和核天体物理学以及其他研究领域都是非常重要的. 用加速器质谱有可能实现对超低含量182Hf的测量. 在中国原子能科学研究院的HI-13加速器质谱装置上对182Hf的测量方法以及样品的化学去钨方法进行了研究, 分别得到了空白样品以及系列标准样品的182Hf和183W的能量-飞行时间双维谱. 182W对182Hf计数的贡献是通过测量183W的计数归一扣除的. 目前本工作对182Hf的测量灵敏度为4.15±10-11 (182Hf/180Hf比值).  相似文献   
10.
聚脲是一类性能优异的高分子材料,具有良好的热稳定性和耐腐蚀性能。聚脲的传统制备方法通常以异氰酸酯为原料,其毒性大且易与水发生副反应。因此,聚脲的绿色合成方法及性能多样的聚脲材料的合成,具有重要的研究意义和潜在应用价值。本文主要综述了聚脲的绿色合成方法,包括直接或间接使用CO2方法合成聚脲的研究进展。从催化剂、二胺分子结构和分子量等角度探讨了对聚脲分子量、热学、力学性能等方面的影响,并且归纳了功能性二氧化碳基聚脲如热塑性聚脲塑料、聚脲弹性体的性能和应用。最后对聚脲材料未来的研究重点和发展趋势进行了阐述。  相似文献   
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