Characterisation of a pre-cell hit detector to be used in single cell irradiation experiments at the Lund Nuclear Microprobe

This paper describes the characterisation of an ultra-thin silicon semiconductor ΔE detector to be used as a pre-cell ion hit detector in single ion experiments on individual, living cells. The characteristics of interest for this specific application are the hit detection efficiency, which has to be close to 100% to enable bombardment with either a single ion or a counted number of ions, the beam spreading, which should be as small as possible to maintain the targeting accuracy, and the vacuum tightness, since the detector is intended, if possible, to be used simultaneously as vacuum window. The hit detection efficiency was shown to be above 99% when detecting alpha particles or 2 MeV protons, the increase in beam size was about 1 μm and the vacuum tightness was comparable to that of the Si₃N₄ wafer which is normally used as vacuum window, thus the ΔE detector fulfils the main criteria to function properly as a single ion hit detector.     

Accuracy of beam positioning in TIARA

A beam scanning and target profiling technique that provides precise and easy beam positioning on samples has been established for the light ion and heavy ion microbeam systems in TIARA of JAERI. The beam positioning accuracy in these systems was measured using nuclear track detectors, CR-39's. The beam positioning accuracy and indirect beam positioning technique in the heavy ion microbeam system enabled extremely low current microbeam to hit targeted virgin points in micro-structure semiconductor test samples for study of single event upset (SEU) transient current properties. This paper gives details of the beam scanning and target profiling system, and describes and discusses the experiments by using this system.     

Design of a single ion hit facility

The aim of this project is to develop a new system for single ion irradiation of cells for genetic and cell biology studies. This charged particle focused microbeam system will provide a fully computer controlled irradiation facility with submicron (subcellular) resolution and will open many new avenues into studies of radiobiological mechanisms. In the first stage of this project a system for single ion detection has been developed. A thin diamond window has been tested as vacuum/atmosphere window and as a possible source of secondary electrons and/or photons for single ion detection. A detection efficiency of 97% has been achieved.     

Microbeam complex at TIARA: Technologies to meet a wide range of applications

Since 1990 R&Ds of microbeam technology has been progressed at the TIARA facility of JAEA Takasaki. In order to meet a wide variety of ion beam applications, analysis, radiation effect studies, or fabrication in regions of micro- or nano-structures, three different types of ion microbeam systems were developed. In these systems, high-spatial resolutions have been achieved and techniques of micro-PIXE, single ion hit and particle beam writing (PBW) were also developed for these applications. Microbeams, on the other hand, require the highest quality of beams from the accelerators, the cyclotron in particular, which was an important part of the microbeam technology of TIARA. In this paper, the latest progress of the ion microbeam technology and applications are summarized and a future prospect of them is discussed.     

Performance of the SIRAD ion electron emission microscope

An axial ion electron emission microscope (IEEM) is now working at the SIRAD irradiation facility of the INFN Laboratories of Legnaro (Italy). The IEEM is used to precisely reconstruct the impact points of single ions, information that may be used to determine the areas of a microelectronic device under test that are sensitive to single event effects (SEE). After describing the setup briefly reviewing its working principles, we show our first time resolved ion induced electron emission images of standard calibration targets. We also discuss a preliminary measurement of ion impact detection efficiency of the IEEM system and the available trigger signals for SEE studies. We finally make an assessment of ion electron emission microscopy at SIRAD and indicate future developments.     

BEPC试验束数据获取系统改进及离线数据分析

运行在BEPC电子直线加速器上的试验束,主要利用在线探测器和离线数据分析选择单粒子事例,满足多种单粒子束流试验.本文介绍了试验束改进后的数据获取系统,以及离线数据分析中的飞行时间谱分析,单粒子判选和粒子击中位置定位等.     

SUERC AMS ion detection

In a short time Be, C, Al, Cl, Ca and I accelerator mass spectrometry (AMS) have been established on the National Electrostatics Corporation (NEC) 5 MV pelletron system at the Scottish Universities Environmental Research Centre (SUERC). While summarising the present performance of the system, this report will focus on the details of ion detection, which sample materials are used and the analytical procedures employed for each individual species during routine analysis.All rare isotope detection is with a single flexible detector and ion event analysis system, but switching of analysed species typically requires a detector reconfiguration. Configurations for routine ¹⁰Be, ¹⁴C, ²⁶Al, ³⁶Cl, ⁴¹Ca and ¹²⁹I detection have been established and will be presented here. Notably, there has proven to be sufficient suppression of the isobaric interferences of ³⁶Cl and ⁴¹Ca in the 5+ charge state using an argon gas stripper at a terminal voltage of 5.0 MV to allow for routine analysis of these isotopes.     

The PTB single ion microbeam for irradiation of living cells

At the PTB's ion accelerators, a new microbeam facility is now in operation that is capable of delivering single ions, for example, to the nuclei of individual living cells. The wide range of proton and ⁴He²⁺ ion energies affords LET-values between 3 and 200 keV/μm. A beam diameter of less than 2 μm outside the vacuum system has been measured and a targeting accuracy of better than 2 μm has been determined. In contrast to other microbeam facilities operated for radiobiological research using mechanical collimators in front of the target to define the beam, the PTB facility utilises beam focusing by quadrupole magnets. The microbeam has a unique ion optical design that incorporates a 90° bending magnet in the beam transport system. This design has the advantage of providing a microbeam basically without scattered particles. Every ion reaching the target is detected by a thin scintillating foil and a photomultiplier tube with efficiency close to 100%. Presently up to 1500 single cells per hour can be automatically irradiated with a chosen number of particles. Procedures and results of first cell irradiations are described as an example.     

Ion microbeam radiation system

An ion microbeam radiation test system has been built for studying radiation-induced charge collection and single event upsets in advanced semiconductor circuits. With this system, it is possible to direct an ion beam of a diameter as small as 1 μm onto a circuit or test structure with a placement accuracy of 1 μm. The components of the system and its operation are described. Applications are described which demonstrate the capabilities of the system     

Application of heavy-ion microbeam system at Kyoto University: Energy response for imaging plate by single ion irradiation

A heavy-ion microbeam system for cell irradiation has been developed using an accelerator at Kyoto University. We have successfully developed proton-, carbon-, fluorine- and silicon-beams in order to irradiate a micro-meter sized area with ion counting, especially single ion irradiation. In the heavy-ion microbeam system, an imaging plate (IP) was utilized for beam diagnostics on the irradiation. The IP is widely used for radiography studies in biology. However, there are a few studies on the low linear energy transfer (LET) by single ions, i.e., low-intensity exposure. Thus we have investigated the energy response for the IP, which can be utilized for microbeam diagnostics.     

Fault monitoring of nuclear power plant sensors and field devices

Existing and new generation of nuclear power plants have economic and reliability concerns as addressed by overall plant performance, unscheduled downtime and the long-term management of critical assets. The key to achieving these needs is to develop an integrated approach for monitoring, control, fault detection and diagnosis of plant components such as sensors, actuators, control devices and other equipment. Both single and multiple fault cases have been considered. This paper presents the following approach for achieving this goal: 1. Development of data-driven system models using Group Method of Data Handling (GMDH), Principal Component Analysis (PCA) and Adaptive Network-based Fuzzy Inference System (ANFIS), 2. Fault detection by tracking model residuals of selected process variables and control functions, and 3. Fault isolation using a rule-based technique and/or a pattern classification technique. This approach is illustrated for a nuclear plant steam generator. Fault detection and isolation (FDI) of sensors and field devices is an important step towards the implementation of an automated and intelligent process control strategy, especially for Generation-IV reactors.     

Ion beam characterization of advanced luminescent materials for application in radiation effects microscopy

The ion photon emission microscope (IPEM) is a technique developed at Sandia National Laboratories (SNL) to study radiation effects in integrated circuits with high energy, heavy ions, such as those produced by the 88” cyclotron at Lawrence Berkeley National Laboratory (LBNL). In this method, an ion-luminescent film is used to produce photons from the point of ion impact. The photons emitted due to an ion impact are imaged on a position-sensitive detector to determine the location of a single event effect (SEE). Due to stringent resolution, intensity, wavelength, decay time, and radiation tolerance demands, an engineered material with very specific properties is required to act as the luminescent film. The requirements for this material are extensive. It must produce a high enough induced luminescent intensity so at least one photon is detected per ion hit. The emission wavelength must match the sensitivity of the detector used, and the luminescent decay time must be short enough to limit accidental coincidences. In addition, the material must be easy to handle and its luminescent properties must be tolerant to radiation damage. Materials studied for this application include plastic scintillators, GaN and GaN/InGaN quantum well structures, and lanthanide-activated ceramic phosphors. Results from characterization studies on these materials will be presented; including photoluminescence, cathodoluminescence, ion beam induced luminescence, luminescent decay times, and radiation damage. Results indicate that the ceramic phosphors are currently proving to be the ideal material for IPEM investigations.     

2.45GHz单电荷态电子回旋共振离子源

描述了一台2．45GHz单电荷态电子回旋共振（ECR）离子源的原理、结构与应用。介绍了其微波系统与磁场结构。在微波输入功率约600W,引出高压22kV,引出孔径为φ6mm时,该离子源的总束流I（H1^ H2^ H3^ )可达90mA。     

一个用于重离子飞行时间测量的平行板雪崩探测器

平行板雪崩探测器很早就用于核物理实验工作。但由于性能的限制,没有被广泛采用;直至七十年代中期,经过较大改进,作为一种精确的时间信号探测器,才又被用于重离子物理实验。由于平行板雪崩探测器输出信号上升时间快、工作介质厚度薄、无辐照损伤、有效面积可以做得相当大、不易受杂散电子干扰等,特别适宜作为用于重离子物理实验的透射型时间信号探测器。通常,平行板雪崩探测器由两片平行电极组成,中间为稀薄的工作气体,两电极间保持恒定的电压。被探测的带电粒子垂直于电极而穿过工作气体,产生原电离,     

电离辐射引起的DNA链断裂损伤及其修复

DNA链断裂是电离辐射的主要生物学效应之一,单链断裂由一次击中造成,所以与辐射剂量成线性关系,双链断裂可以一次击中造成,也可由两个位置相关的单链断裂迭加而成,所以与辐射剂量成线性——平方关系。已有各种理化方法能测定活细胞内的单链断裂和双链断裂数。细胞具有修复DNA链断裂的能力,但其机制远不如切除修复机制那么清楚。未修复的链断裂是致死的,被修复的单链断裂完全恢复DNA的正常结构与功能,被修复的双链断裂的生物学效应如何还不清楚。剂量率对辐射的生物学效应有重要影响。     

Design of Readout Electronics System for Prototype LAr-based Direct Dark Matter Detector

The prototype readout electronics system of direct dark matter detection experiments, which is mainly based on high speed and high precision waveform sampling and high speed data transfer techniques, consists of multiple waveform digitization modules (WDMs) and one global trigger module (GTM). The WDM exploits high speed analog-to-digital converter to acquire signals from the photomultiplier tubes (PMTs). The GTM collects hit information from WDMs, generates system trigger signal and fans out synchronous clock to all WDMs via backplane buses. Based on offline pulse shape discrimination method, the nuclear recoil events from a PuC neutron source can be clearly distinguished from gamma events within the energy range of 80 pe (photoelectron) to 240 pe for gamma rays, which indicates the capability of fulfilling the requirements of LAr-based direct dark matter detection experiments in future.     

面向暗物质直接探测的原型液氩探测器读出电子学系统设计

针对面向暗物质直接探测的t级原型液氩探测器的信号读出需求，本文设计了1套基于高速、高精度波形数字化技术及PXI Express高速仪器总线技术的读出电子学系统。该系统采用多个波形数字化模块和1个全局触发模块，实现单机箱40路光电倍增管信号的同步采集。系统具有很好的灵活性和可扩展性，通过将多个机箱的触发模块级联可进一步将系统规模扩展至数百通道。该系统研制完成后，配合1个10 kg级的小型液氩探测器开展了单光电子标定和放射源联调测试。通过放射源测试，获得了高质量的液氩探测器闪烁光信号波形。利用脉冲形状甄别算法，可清晰区分核反冲事例和γ事例，初步结果表明，在80~240 pe(光电子)信号幅度范围内的17万个事例中，没有电子反冲信号被误判为中子信号，验证了读出电子学技术路线和设计方案的可行性。     

Estimation Method for Exchange Capacity of Mixed Bed Using Monitoring Minicolumns

The methods of estimation of the exchange capacity of mixed bed demineralizer used in nuclear power plants were studied for the purpose of protection against contamination of condensed water with leaked sea water flowing as a coolant in the heat exchanger. It was identified by numerical calculations and experimental works that the performance of mixed bed could be represented by the model for a system of single sort of ion exchange resin and single solute.

The intraparticle diffusivities and ion exchange equilibrium constants for the monitoring minicolumns can be obtained experimentally with the breakthrough curves for different packed height and the equilibrium constant for lm packed height can be known by extrapolation. The constants for 1 m packed height are substituted to the theoretical approximate formula which has been already recognized as a solution for the transient behavior of the adsorption system of a single solute, then the breakthrough time for actually working column of 1 m packed height can be calculated. For the rough estimation of degree of degradation for the deteriorated resin, a simple prediction method was presented in which the relations between the initial concentrations of the effluent from the minicolumns and the packed heights were applied.     

基于MPD-4电子学插件的液体闪烁体中子光响应特性实验研究

中子光响应函数是液体闪烁体探测器的重要参数，准确的光响应函数和探测阈值是精确确定中子探测效率的基础。近年来，专门用于液体闪烁体中子探测器的高集成度新型电子学插件（Mesytec公司的MPD-4）广泛应用于中子探测系统中，该电子学插件集成了脉冲高度（PH）、脉冲形状甄别（PSD）和恒比定时（CFD）测量功能，且1个NIM插件即可实现4路探测器的同时测量。对于同一中子探测器，利用这一电子学系统与传统电子学系统对中子的光响应函数进行了实验比对，结果表明，两套系统得到的中子光响应函数具有明显的差异。因此，在使用MPD-4电子学系统进行中子探测的实验中，需对光响应函数进行重新标定。     

Methodologies for hydrogen determination in metal oxides by prompt gamma activation analysis

Prompt gamma activation analysis (PGAA), available at The University of Texas at Austin (UT), has been employed for the direct determination of hydrogen content in a series of metal oxide materials typically used as cathodes in lithium ion battery systems. Special attention was given to the experimental setup including potential sources of error and system calibration for the detection of hydrogen. Spectral interference with hydrogen arising from cobalt was identified and corrected for. Limits of detection as a function of cobalt mass present in a given sample are also discussed. PGAA has proven to be a novel and precise technique for the determination of hydrogen in metal oxides. This type of investigation could provide valuable insight regarding the factors that limit the practical capacities of lithium ion oxide cathodes.