Accelerator mass spectrometry with the 14UD accelerator at the Australian National University

The present status of the AMS activities at the Australian National University is described. Particular attention is paid to methods and equipment that have evolved substantially since earlier reports.     

A recoil mass spectrometer for HHIRF

A recoil mass spectrometer (RMS) is to be built that will carry out a broad research program in heavy-ion science at the Holifield Heavy Ion Research Facility at Oak Ridge, Tennessee. The RMS will make possible the study of otherwise inaccessible exotic nuclei. Careful attention has been given to match the RMS to all the beams available from the HHIRF accelerators, including those beams with the highest energy as well as massive particles for use in inverse reactions. The RMS is to be a momentum achromat followed by a split electric dipole mass spectrometer of the type operating at NSRL at the University of Rochester. The RMS is essential for many of the proposed experiments on short lived and/or low cross section products. The spectrometer design will be discussed, with attention paid to the aberrations present and their corrections.     

Performance of the new single stage accelerator mass spectrometer at the SUERC

A NEC 250 kV single stage accelerator mass spectrometer (SSAMS) has been installed along-side our five year old 5 MV spectrometer. The new instrument is intended to take over routine radiocarbon measurement, thereby providing more capacity for our rapidly growing cosmogenic nuclide programme. Initial tests show that although flawed the SSAMS sufficiently mimics the good performance of the first machine; high-precision ¹⁴C/¹³C measurement is being achieved with a background limited by sample preparation.     

LNL的反冲质量谱仪的新型焦面探测器——PS-PPAC

在意大利 L NL实验室 ,研制了两种新型反冲质量谱仪 (RMS)焦面探测器 :灵敏面积均为70 mm× 140 mm的 Padova型和 Argonne型位置灵敏 -平板雪崩计数器 (PS- PPAC)。详细描述了紧密结构的特点及主要特性 ,各自的性能测试方法及结果。对α源 (能量为 5 .5 Me V) ,Padova型 PPAC的 X、Y位置分辨分别为 1.0和 0 .8mm,对应的探测效率分别为 4 9%和 85 % ,Argonne型 PPAC的 X、Y位置分辨分别为 1.8和 1.0 mm,对应的探测效率分别为 12 .7%和 4 .5 %。     

The next chapter in radiocarbon dating at the Australian National University: Status report on the single stage AMS

In February 2007, a single stage AMS from the National Electrostatics Corporation (NEC) was installed at the Research School of Earth Sciences at the Australian National University. This instrument is equipped with a gas/graphite hybrid ion source allowing direct analysis of CO₂ as well as traditional graphite targets. The instrument was funded by an Australian Research Council grant and by a consortium of eight universities plus the CSIRO Division of Land and Water. Its purpose is to support integrated environmental and archaeological research and access is open to the wider research community. In the first year ～1500 samples have been analysed. A precision of ～3‰ is routinely observed. The background for processed graphite (coal, calcite, Carrera marble) is better than 45,000 years. This paper summarizes the first year of measurements.     

Accelerator mass spectrometry at the University of Pennsylvania

Since 1979 over 1000 measurements have been made on ¹⁰Be and about 50 on ²⁶Al. Although the experimental program is diverse, emphasis has been placed on the study of ¹⁰Be in the environment, particularly its rate of influx in precipitation, its retention by soil and transport by ground water. The global flux for 1982–1983 is estimated to be 0.33 at. cm^?2 s^?1. The application of ¹⁰Be as a tracer is discussed and the results of 46 measurements on lavas from island-arc volcanoes and 47 Australasian tektites are presented. ²⁶Al has also been measured in 6 tektites and the observed ²⁶Al:¹⁰Be ratio is consistent with a terrestrial origin. Exploratory measurements have been made on a wide range of terrestrial and extraterrestrial samples including several organic materials such as peat, oil, coal, teeth, shells and trees.     

A linear mass spectrometer by induced Hall potential for electromagnetic isotopic separation working at high pressures

In this paper a novel alternative for bulk electromagnetic separation working at high pressures is proposed. It is shown that if a self-induced Hall potential is stimulated in the boundaries, the system will be able to take advantage of the collisions process, boosting the isotopic separation and resulting in a linear-spectrometer with a higher spatial separation per unit length than a traditional calutron. Although originally the concept was devised for the production of medical isotopes where the minority isotope to be separated is produced by neutron capture and is the heavier isotope, if the Hall potential is replaced by an external electrical field, the concept is equally applicable for situations where the minority isotope is the lighter one, as for example in the enrichment of uranium. Additional R&D is required to explore further the possibilities of this concept and to identify optimal values for several of the system design variables.     

Results of radioisotope measurements at the NSF-University of Arizona tandem accelerator mass spectrometer facility

In this paper we will describe the operation of the University of Arizona tandem accelerator mass spectrometer (TAMS) facility, present results of some measurements performed to demonstrate the reliability of its performance, and describe several experiments which have been completed on samples of archaeologic and geophysical interest.     

Accelerator mass spectrometry of 14C at Nagoya University

The Tandetron accelerator mass spectrometer was installed at Nagoya University in 1982. In addition to the investigation of sample preparation, radiocarbon measurements and the application to natural samples, tests have been performed by using graphitized carbon and carbon-silver targets. Of these, graphite targets give an ion beam current as high as 30 μA for ¹²C^? ions and ¹⁴C-results with a precision of better than ± 0.4% in measurements of ¹⁴C/¹³C. C-Ag targets are also satisfactory and give a precision in the region of ± 2.0% for ¹⁴C/¹³C. ¹⁴C measurements of tree rings, grown from 1950 to 1983, give a maximum ¹⁴C concentration during 1964.     

The detector system of the BigSol spectrometer at Texas A & M

The detector system used at the first focus of the BigSol superconducting solenoid beam line at the Texas A & M superconducting cyclotron is presented. The system is composed of a position sensitive PPAC followed by an ionization chamber (IC) with a YAP(Ce) array in its back plane. The position sensitivity of the PPAC as well the energy resolution of the IC is investigated as a function of the counting rate. Pulse height, pulse height resolution and time resolution of the YAP(Ce) crystals are studied for a variety of heavy ion beams ranging from ²⁰Ne to ¹⁹⁷Au at energies from 15 AMeV to 40 AMeV. The pulse shape discrimination method using a Flash ADC is also explored, in order to identify decay products (alpha particles and electron/gamma) from the fragments implanted in the scintillator.     

中能重离子核反应产物测量装置4π带电粒子探测设备的研制

介绍了4π带电粒子多探测器系统。该系统由276个探测器单元组成，每个单元分别由快、慢塑料闪烁体、碘化铯晶体、硅半导体探测器所组成的望远镜构成，总立体角覆盖约86％的4π以及有一个很低的能量探测阈，整个探测器系统轴向对称排列，工作在真空中，该探测器系统可以鉴别氢、氦的同位素，具有大的能量测量动态范围。     

磁质子反冲谱仪磁分析器的设计与谱仪性能研究

设计一种用于紧凑型磁质子反冲(magnetic proton recoil,MPR)谱仪的小型单聚焦磁分析器,用钕铁硼二级永磁铁作分析磁铁,焦平面探测器为CR39。用实际磁铁的磁场分布数据和带电粒子输运程序分析磁分析器的性能,并用Pu-239α源实验标定。结合粒子输运程序的结算和蒙特卡罗模拟,研究了MPR谱仪的整体性能。结果表明:磁分析器能对3.5-8.5MeV范围内的质子和α粒子进行动量分析,有良好的动量色散和径向聚焦能力,符合紧凑型MPR谱仪的设计要求;对14MeV的DT聚变中子,谱仪有4%的能量分辨率和10-8的探测效率。     

CMRR中子自旋回波谱仪引束导管模拟研究

中国绵阳研究堆(China Mianyang Research Reactor,CMRR)采用由弯导管和直导管组成的引束导管偏转第三条冷中子管(C3)冷中子束第二端口(C32)上部区域内的中子束流,为自旋回波谱仪提供中子束。应用中子射线追踪程序McStas 2.5对引束导管进行蒙特卡罗模拟,从弯导管通道个数、曲率半径以及超镜因子三个方面,考察引束导管设计方案以验证其设计可行性。结果表明:1)弯导管通道个数设计值合理;2)弯导管曲率半径取值在谱仪与屏蔽体安装空间可接受情况下,应尽量大;3)弯导管超镜因子取2.5时,引束导管出口与样品处中子通量可达到最大强度。根据模拟计算结果,弯导管超镜因子设计值偏大,引束导管设计方案总体具有可行性。     

Cold fusion experiment at Department of Nuclear Engineering,National Tsing-Hua University

We have repeated the so-called cold fusion experiment by electrolyzing heavy water, with 0.1M LiOD, with palladium rod as the cathode and platinum wire as the anode. The purpose of our experiment is to dectect the neutrons that are produced from the fusion process of deuterium if fusion does occur. We use one³He detector and one BF₃ detector to detect the thermal neutrons coming out of the water bath that surrounds the heavy water cell. Possible neutron bursts are detected by the³He detector during a period of about 7 h after electrolyzing for 11 days.     

Status and research programs of the multinuclide accelerator mass spectrometry system at the University of Tsukuba

We present the current status and research programs of a multinuclide accelerator mass spectrometry (AMS) system on the 12UD Pelletron tandem accelerator at the University of Tsukuba (Tsukuba AMS system), Japan. A maximum terminal voltage of 12 MV is available for the AMS system. The Tsukuba AMS system can measure environmental levels of long-lived radioisotopes of ¹⁴C, ²⁶Al, ³⁶Cl and ¹²⁹I by employing a molecular pilot beam. Recently, enhancements in AMS techniques and equipment, including sample preparation, the ion source and the data acquisition system, have improved the performance of ³⁶Cl-AMS. The standard deviation of fluctuations is typically ±2%, and the machine background level for the ³⁶Cl/Cl ratio is lower than 1 × 10^?15 with a halite sample. We have measured over 500 samples in 1 year, including samples for earth and environmental sciences and nuclear safety research.     

超灵敏小型回旋加速器质谱计技术特性和设计准则

系统地介绍超灵敏小型回旋加速器质谱计固有的技术特性、特殊的设计准则和新颖的技术路线.     

Simulation and test of the SLEGS TOF spectrometer at SSRF

The Shanghai laser electron gamma source (SLEGS) is a powerful tool for exploring photonuclear physics, such as giant dipole resonance (GDR) and pygmy dipole resonance, which are the main mechanisms of collective nuclear motion. The goal of the SLEGS neutron time-of-flight (TOF) spectrometer is to measure GDR and specific nuclear structures in the energy region above the neutron threshold. The SLEGS TOF spectrometer was designed to hold 20 sets of EJ301 and LaBr3detectors. Geant4 was used to sim...     

Design Features and Commissioning of the Versatile Experiment Spherical Torus (VEST) at Seoul National University

A new spherical torus called VEST (Versatile Experiment Spherical Torus) is designed,constructed and successfully commissioned at Seoul National University.A unique design feature of the VEST is two partial solenoid coils installed at both vertical ends of a center stack,which can provide sufficient magnetic fluxes to initiate tokamak plasmas while keeping a low aspect ratio configuration in the central region.According to initial double null merging start-up scenario using the partial solenoid coils,appropriate power supplies for driving a toroidal field coil,outer poloidal field coils,and the partial solenoid coils are fabricated and successfully commissioned.For reliable start-up,a preionization system with two cost-effective homemade magnetron power supplies is also prepared.In addition,magnetic and spectroscopic diagnostics with appropriate data acquisition and control systems are well prepared for initial operation of the device.The VEST is ready for tokamak plasma operation by completing and commissioning most of the designed components.     

Determination of the isotopic composition of hydrogen and helium on the MI 3305 specialized mass spectrometer

A. A. Bochvar All-Union Scientific-Research Institute of Standardization in Machine Building. Translated from Atomnaya énergiya, Vol. 76, No. 2, pp. 125–127, February, 1994.