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1.
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
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.
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
4.
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.
The schematic layout and principle of a Bragg curve detector were showed in this paper. A Bragg curve detector was systemically modified and its performance was improved. The total energy resolution of the detector is 0.9% for alpha particle at energy of 5.48 MeV from 241Am source, and the Bragg Peak resolution is 1.6%. Measurement of medium-weight nuclides by using the Bragg curve detector were carried at CIAE-AMS system. series of 36Cl and 41Ca standard samples were measured. The results showed that this Bragg curve detector could clearly identify isobars 36Cl-36S and 41Ca-41K. The results also showed that the ΔZ/Z of 1/47, corresponding to Bragg Peak resolution is 2.1% at ion atomic number of about 16. The Bragg curve detector can be successfully used for AMS measurement. 相似文献
6.
By using HPGe γ-ray spectrometry, the activity of the long-lived fission product 126Sn in a SnOB2 sample was measured. The number of 126Sn atoms and the ratio of 126Sn to Sn were calculated based on the half-life value of 2.35×105a and the chemical stoichiometry. The result of the ratio of 126Sn to Sn, (1.033±0.037)×10-8, is consistent with the results measured by the accelerator mass spectrometry (AMS) within uncertainty limits, which confirms our procedures in the measurement of 126Sn by AMS and lays a foundation for the AMS measurement of 126Sn at much lower levels. 相似文献
7.
董克君 何明 李振宇 王祥高 李朝历 游曲波 包轶文 武绍勇 沈洪涛 管永精 张伟 凡金龙 杨磊 孙宏清 丁有钱 贺国珠 李世琢 龚杰 何贤文 陆丽燕 王伟 胡跃明 袁坚 张生栋 常永福 姜山 《中国物理快报》2010,27(11):27-30
Accelerator mass spectrometry (AMS) is one of the most promising methods to detect minute amounts of 182Hf. However, the sensitivity of 5×10^-11 for ^182Hf/180Hf obtained previously by the AMS method at China Institute of Atomic Energy (CIAE) cannot meet the requirement of some applications. We present some new improvements of measurement method for AMS measurement of 182Hf at the CIAE HI?13 tandem accelerator system. As a result, a sensitivity of 1.0×10^-11 for 182Hf/180Hf is achieved. 相似文献
8.
宇宙成因核素 53Mn是一种非常理想的地貌演变研究工具。近年来, 随着加速器质谱(AMS)技术的不断发展, 人们已能够进行53Mn的高灵敏测量。介绍了53Mn在地球科学中的应用前景、 国际研究现状及中国原子能科学研究院目前正在开展的53Mn高灵敏AMS测量方法的研究。The determination of cosmogenic 53Mn concentrations found in terrestrial formations has many interesting applications for Earth Sciences. With Accelerator Mass Spectrometry (AMS) it should be possible to detect minute amounts of 53Mn. The situation of international research of 53Mn AMS measurement and applications are presented. The AMS measurement method of 53Mn at China Institute of Atomic Energy and its applications prospect are to be explored. 相似文献
9.
236U是一种长寿命放射性核素, 其半衰期为T1/2=2.342(3)×107 a, 在自然界的含量极微, 天然铀中 236U/238U的原子比约为~10-14。 目前, 对于236U及其测量的研究报道较少。首先介绍了236U的产生, 并对地球中 236U的总量进行了估算。 概述了236U测定在亿年级中子注量率积分评估、 核环境和核活动监测, 以及地质学等领域中的重要应用。 最后,对国内外加速器质谱(AMS)测量236U的状况进行了综述,报道了中国原子能科学研究院AMS小组通过对同位素干扰鉴别的多方面研究, 初步建立了236UAMS测量方法。 236U is a longlived radionuclide with half life of 2.342(3)×107 a. The ratio of 236U/238U is about 10-14 in the natural Uranium. The origin and production of 236U in globe are introduced and estimated in this paper,respectively. The major applicationsion of 236U as a 100 million year neutron flux integrator,as a “fingerprint” for monitoring nuclear environment and nuclear activity,and as a tracer in geological studies are briefly summarized. The accelerator mass spectrometry(AMS) measurement of 236U in the world and the research on HI 13 tandem accelerator at China Institute of Atomic Energy(CIAE) is also mentioned in this paper. 相似文献
10.
Accelerator mass spectrometry (AMS) measurement of 59Ni has been established at CIAE with the HI-13 tandem accelerator and the recently developed ΔE-Q3D detection system. 59Ni standard and commercial NiO samples were measured to check the performance of the ΔE-Q3D detection system on 59Ni isobar separation and suppression. An overall suppression factor of about 107 for the interfering isobar 59Co resulting in detection sensitivity as low as 3.8×10-13 atomic ratio (59Ni/Ni) has been obtained. Based on these techniques, the AMS measurement method of 59Ni with high sensitivity is developed. 相似文献