Accelerator mass spectrometry

In this overview the technique of accelerator mass spectrometry (AMS) and its use are described. AMS is a highly sensitive method of counting atoms. It is used to detect very low concentrations of natural isotopic abundances (typically in the range between 10(-12) and 10(-16)) of both radionuclides and stable nuclides. The main advantages of AMS compared to conventional radiometric methods are the use of smaller samples (mg and even sub-mg size) and shorter measuring times (less than 1 hr). The equipment used for AMS is almost exclusively based on the electrostatic tandem accelerator, although some of the newest systems are based on a slightly different principle. Dedicated accelerators as well as older "nuclear physics machines" can be found in the 80 or so AMS laboratories in existence today. The most widely used isotope studied with AMS is 14C. Besides radiocarbon dating this isotope is used in climate studies, biomedicine applications and many other fields. More than 100,000 14C samples are measured per year. Other isotopes studied include 10Be, 26Al, 36Cl, 41Ca, 59Ni, 129I, U, and Pu. Although these measurements are important, the number of samples of these other isotopes measured each year is estimated to be less than 10% of the number of 14C samples.     

53Mn/55Mn实验室标准样品制备及加速器质谱测量

宇宙成因核素⁵³Mn是一种非常理想的地质定年工具。近年来,随着加速器质谱（AMS）技术的不断发展,⁵³Mn的高灵敏测量成为可能。本工作介绍了⁵³Mn/⁵⁵Mn的系列实验室标准样品的制备以及AMS测量,结果表明：⁵³Mn/⁵⁵Mn的测量值与标称值在误差范围内比较吻合且呈现良好的线性关系,中国原子能科学研究院的AMS系统对⁵³Mn的测量灵敏度可以达到10^-14。     

第四纪地质年代学和定年方法及应用

第四纪样品的同位素定年是一个常见的较困难的地质问题。近几年来，由于质谱分析、热电高质谱计、加速器质谱计和样品分离技术的进步，第四纪地质年代学及定年方法发展非常迅速。K－Ar和Ar－Ar定年、14C、铀系、FT、TL和ESR定年等已能为地球演化及第四纪以来古气候及古环境的变化提供准确的时间标尺。宇宙成因核素，例如10Be、26Al、36Cl和39Ar可以用于地球表面的侵蚀定年、冰川作用和冰川消退定年、地下水年龄测定及地球物质形成年龄和暴露年龄的测定，大大提高了测量灵敏度、测量精度和测量速度。这些定年方法在第四纪地质年代学和同位素地质科学中获得了很大进展。上述方法的实现及潜在的应用将在第四纪地质学及地球科学中发挥重要作用。本文讨论了这些方法的特点、优越性、局限性及其意义。     

碘的质谱测量方法研究进展

近年来,电感耦合等离子体质谱（ICP-MS）技术的发展着力于应对基质更加复杂的样品和解决测量过程中的干扰问题,同时与进样、分离系统的联用技术也在快速发展,而加速器质谱（AMS）则朝着更加小型化和更高灵敏度的方向发展。ICP-MS测量前需要对样品进行前处理以消解和提取碘,而AMS测量前则还需对样品进一步分离富集和纯化。本文总结了ICP-MS和AMS的发展概况及其在碘测量方面的应用,归纳了ICP-MS和AMS测量含碘样品的前处理方法,综述了国内外总碘、碘同位素及碘形态的质谱测量方法新进展。     

加速器质谱法测量99Tc

99Tc is a fission product, and it has high fission yield (6%) and very long half-life (2.1×105 a). With the movement of nucleus, the concentration of 99Tc is increasing in the circumstance. So it's important to measure the concentration of 99Tc in the circumstance, and accelerator mass spectrometry (AMS) might be the best method for 99Tc measurement. The 93Nb is used for AMS instrument normalization, sample matrix. And we used the difference of energy loss and deducting the isotope to measure the 99Tc in a series of standard samples. And the results show that the AMS is the feasible measurement method.     

Methods for determining the composition of nasal fluid by X-ray microanalysis

The nasal fluid is an easily accessible form of airway surface liquid. The objective of this study was to find a technically easy and reproducible method for sampling and analysis of this fluid. In a pilot study, several methods to carry out X-ray microanalysis of sub-microliter droplets were compared. Acceptable results were obtained with several of these methods (pipeting on filter paper or analysis of frozen-hydrated droplets at low temperature). Nasal fluid was collected from the inferior turbinate with a micropipette after occlusion of a nostril for 5-10 minutes. Ion concentrations in nasal fluid from six control subjects were (in mM, mean +/- standard error): sodium (Na) 127 +/- 6, chloride (Cl) 140 +/- 7, potassium (K) 27 +/- 3, and calcium (Ca) 5 +/- 1. This sampling method proved difficult to apply to cystic fibrosis (CF) patients because of the viscous quality of their nasal secretion. Therefore, an alternative method was devised. Sephadex G-25, ion exchange beads were mounted on double-sided tape, which was stuck on a filter paper as support. The filter paper was applied for 10 minutes to the nostril of a subject, and kept loosely in place. During the exposure period, the nasal fluid equilibrates with the beads. After removal of the filter paper with the beads from the nostril, the beads were rinsed with a hydrophobic volatile silicone oil to remove excess nasal fluid, dried, and analyzed. This method of collection is not cumbersome for the subject and gives results similar to those obtained by the direct collection method: Na 142 +/- 28 mM, Cl 150 +/- 36 mM, K 43 +/- 10 mM (mean and standard error of four determinations). Small differences between the filter method and the bead method can be explained by the fact that the filter method measured total nasal fluid, whereas the bead method measures predominantly the fluid component. Subjects suffering from mild respiratory illness or rhinitis had higher values for Na, K, and Cl in their nasal fluid.     

32Si半衰期的加速器质谱测量方法研究

³²Si是宇宙射线与空气中的Ar通过散裂反应产生的长寿命放射性核素,利用³²Si可以开展广泛的应用研究。然而作为放射性核素关键数据的³²Si半衰期数据仍然存在较大的偏差,这在很大程度上阻碍了³²Si的应用。本工作利用中国原子能科学研究院的加速器质谱系统开展了³²Si半衰期的测量。通过反应堆辐照Mg₂P₂O₇生产³²Si并制备出用于加速器质谱测量和活度测量的样品;利用加速器质谱技术进行了³²Si/Si绝对比值的测定;通过液闪对样品进行了放射性活度测量,从而实现了³²Si半衰期的测定,得到³²Si的半衰期值为(182±16)a。     

DCOM and MMS–based control software architecture for automated manufacturing system

In this paper, we introduce the manufacturing message specification (MMS) and compare two distributed object approaches–distributed component object model (DCOM) and common object request broker architecture (CORBA), suggest characteristics that DCOM is more suitable for automated manufacturing system (AMS) control software integration. In order to make a control system provided with interoperability and reconfigurability etc., a hybrid control system is built for AMS, then a control software architecture is presented for AMS based on distributed object DCOM middleware and MMS standard. The object-oriented DCOM communication protocol is used to implement the MMS in a distributed object mode. DCOM and MMS combination brings the operating system independent communication capabilities to manufacturing devices such as CNC machine tools and industrial robots in AMS. Control software implementation of MMS concepts in the DCOM environment is particularly discussed. Finally, to verify the control software architecture for AMS, prototype development has been implemented in VC++ 6.0 developer environments.     

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.