中重核加速器质谱测量实验谱的预先研究

加速器质谱(AMS)测量需排除同位素和同量异位素及其它本底的干扰。在中重核素的AMS测量中，干扰本底尤为严重，这给在束确认实验谱中所对应的各核素和实验谱的核素分析带来一定困难。为解决这一问题，我们设计编写了中重核加速器质谱测量实验谱的模拟程序，它可在实验前预先设定最佳实验条件和给出待测核素及可能进入超灵敏加速器质谱探测器中的各干扰核素的计算值。利用该程序的计算结果对照实验测量数据，可在束确认实验谱中的待测核素。     

加速器质谱测量^182Hf等长寿命重核素标准样品的制备

通过对长寿命重核素^182Hf、^151Sm等的测量可以确定某些场合的中子注量，能够确定长寿命放射性核素的迁移行为，对核废物安全处置研究具有重要意义。加速器质谱(AMS)技术是实现^182Hf、^151Sm等高灵敏测量的有效方法(测量灵敏度可达到10^-15)，但AMS测量是一种与标准样品比对的相对测量，市场上无所需标样，需自行制备。     

加速器质谱测量32Si的方法研究

宇宙成因核素32Si的半衰期约为140a,非常适合于100~1000a的测年和研究地球生物化学中的全球硅循环。由于自然界中的32Si同位素丰度非常低（〈10^-14）,因此,利用衰变计数法测量效率也非常低。为此,将研究利用加速器质谱（AMS）方法测量32Si。     

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。     

73 加速器质谱测量^182Hf的研究

^182Hf是一个对研究太阳系早期历史特别重要的长寿命放射性核素。本工作在中国原子能科学研究院的HI-13串列加速器质谱装置上对^182Hf进行了测量。     

加速器质谱测量60Fe方法的模拟研究

长寿命的放射性核素⁶⁰Fe在天体物理学等许多研究领域中有重要科学意义。利用高能量的HI-13串列加速器质谱（AMS）系统和高性能的Q3D磁谱仪,初步研究了⁶⁰Fe的测量方法。通过优化测量条件,利用⁵⁸Fe和⁵⁸Ni分别模拟⁶⁰Fe和⁶⁰Ni,获得了仪器压低同量异位素的能力。结果表明,通过ΔE-Q3D系统结合四阳极气体电离室技术,将Ni的干扰压低了10¹¹。化学方法压低Ni的干扰为10⁴。可以预测⁶⁰Fe/Fe的探测灵敏度为10^-15。     

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。     

加速器质谱测量129I方法的改进

在筑波大学的12UD串列加速器上开发了一套改进的129I加速器质谱(AMS)测量方法,包括在120°磁铁后安装了一副自行设计制作有静电偏转板,有效改善了对127I束流和129I计数的测量;采用97MoO2分子导航束稳定加速器端电压,加速器的端电压能稳定在几天内不超过0.1%,结合二次剥离,取得了满意的测量效果.用该方法测得AgI试剂样品的本底水平为7.83×10-13.对129I/127I比值范围为(4.92～0.28)×10-10的一系列样品的测量不确定度在7%以下,准确度较前有所提高.     

用于加速器质谱测量的^15Sm标准样品研制

^151Sm是一种长寿命（T1／2=90a）裂变产物核素，对^151Sm的精确测量可以为环境科学、生命科学、核数据等领域提供重要信息。然而，^151Sm在样品中的含量很低，放射性弱，加速器质谱（AMS）是实现^151Sm高灵敏测量的有效方法。AMS是一种与标准样品比对的相对测量方法，本工作主要涉及^151Sm标准样品研制。     

Simulation of experimental spectra for medium-heavy nuclides in accelerator mass spectrometry

Some interferences are often encountered in accelerator mass spectrometry （AMS） measurements, especially for medium-heavy nuclide measurement, It is difficult for online discrimination of the nuclide of interest from the interfering ones. In order to solve this problem, we developed a method to simulate the experimental spectra of medium-heavy nuclides in AMS measurements. The results obtained from this method are in good agreement with experimental values.     

Spallogenic nuclides in meteorites by conventional and accelerator mass spectrometry

Light noble gases and ¹⁰Be were determined in 15 ordinary chondrites by conventional mass spectrometry and accelerator mass spectrometry, respectively. Aliquots of these samples had previously been studied for ²⁶Al and ⁵³Mn. Be was extracted from 10–20 mg of meteorite and ¹⁰Be was determined by means of the 6 MV tandem Van de Graaff accelerator at ETH-Zürich with a reproducibility better than 3%. A detection limit of 0.7 dpm/kg meteorite was achieved. Based on the noble gas data a ¹⁰Be production rate of 17.8 ±0.4 dpm/kg was established for chondrites with H-group chemistry. Short exposure ages of meteorites were determined via the ¹⁰ Be concentrations. A slight correlation of ¹⁰Be production rates with shielding could be observed. During the last 4 million years the long-term averaged cosmic ray intensity did not vary by more than 30%.     

Studies of Al metabolism in animal by accelerator mass spectrometry

The correlation between Al metabolism and senile dementia in animal has been studied by AMS(accelerator mass spectrometry).Three groups of laboratory rats were fed with normal food.food with high Al content,and with enriched Ca and Mg together with high Al,respectively for six to eight months.Mapping test was made to recored th degree of wisdom degeneration.Half of the rats were sacrificed and Al contents in various organs were measured by atomic absorption spectroscopy.The rest were injected with ^26Al,killed after 5,10,15,25,and 35d and ^26Al contents measured by AMS.The distribution of Al as well as the correlation among the accumulation of ^26Al,and the existed Al content and dementia was studied.     

Design and reality: Continuous-flow accelerator mass spectrometry (CFAMS)

In 2007 we published [1] the design of a novel accelerator mass spectrometry (AMS) system capable of analyzing gaseous samples injected continuously into a microwave plasma gas ion source. Obvious advantages of such a system are drastically reduced processing times and avoidance of potentially contaminating chemical preparation steps. Another paper in these proceedings will present the progress with the development of the microwave gas ion source that has since been built and tested at the National Ocean Sciences AMS Facility in Woods Hole [2]. In this paper we will review the original design and present updates, reflecting our recent encouraging experience with the system. A simple summary: large acceptance ion beam optics design is beneficial to accelerator mass spectrometry in general, but essential to AMS with plasma gas ion sources.     

Measurement of 79Se by accelerator mass spectrometry using projectile X-ray technique

1IntroductionInacceleratormassspectrometry(AMS)measurementsoflong-livedradioisotopes,stableisobarsarethedominantbackground.FortheradioisotopesofatomicnumberZ520,theisobarsbackgroundcanbeeliminatedbymeansofthedifferentenergylossofisobarinmatterduetotherateofenergylossisafunctionofZ.Butwithincreasingatomicnumber,theenergystragglingincreasesrelativetotheenergylossdifference,sothatisobarseparationbecomesprogressivelylesseffective.Inordertoseparatetheisobarswithhigheratomicnumberstheionenergyhast…     

Measurement of Sm with the HI-13 accelerator mass spectrometry system

¹⁵¹Sm is an interesting nuclide in many research fields. Measurement methods of the long-lived ¹⁵¹Sm with accelerator mass spectrometry have been developed at China Institute of Atomic Energy. The chemical form of samples was Sm₂O₃ and the extracted ion was SmO⁻. To date, the sensitivity, that is, the isotopic ratio, of ¹⁵¹Sm measured using accelerator mass spectrometry is about 10⁻⁸. This method was also used to measure the concentration of tracer ¹⁵¹Sm in biological samples for clarifying whether the rare earth elements can enter into the brain. It is not possible at present to determine whether the tracer has penetrated the blood-brain barrier into the brain.     

中子活化测量谱的计算机自动识别

介绍了一个在微机上建立的中子活化分析核素的自动识别系统,它具有简便快速、高效准确等优点。它基于常规的谱数据处理结果,即输入的数据包含峰位能量、峰位面积和面积的不确定度。利用中子活化分析数据库进行核素识别。利用该软件我们进行了大量的活化分析的核素识别,比较适用,取得了较满意的结果。     

加速器质谱计在地球科学中的应用

本文介绍加速器质谱计用于测定天然物质中超微量同位素~(10)Be及其在地球科学中的应用。环绕样品~(10)Be的测定可用于研究大气和海洋中发生的各种传输作用过程;大陆沉积物~(10)Be分布及迁移直接与黄土(或土壤)的堆积和侵蚀有关。~(10)Be是一种反映各种地球化学作用过程的理想的示踪剂。     

A review of ion sources for accelerator mass spectrometry

Accelerator mass spectrometry places unusually difficult demands on ion source design and possible ways of meeting these are discussed. A brief review of the state-of-the-art methods of generating negative ion beams of beryllium, carbon, aluminum, chlorine and calcium are presented. A new method of producing 20–25 μA of ¹²C^? ions from CO₂ gas is described in detail with emphasis on accelerator ¹⁴C dating. Ionization efficiency is high (～ 7.7%) and it may be possible to date samples containing 100 μg of ¹²C (i.e. ～ 0.2 at. cm³ of CO₂). Accelerator measurements with contemporary CO₂ followed by CO₂ from anthracite enabled the age of the latter to be determined to be > 39000 years without background subtraction.     

加速器质谱(AMS)测量中的粒子鉴别探测器

描述了中国原子能科学研究院AMS测量中使用的飞行时间探测器、多阳极电离室、Bragg探测器、入射离子X射线探测器以及充气飞行时间探测器。通过它们可以获得粒子的飞行时间、部分能量和总能量,从而达到粒子鉴别的目的。介绍了采用这些探测器在HI—13串列AMS系统上做的相关工作以及取得成果。