Display System for Use with a Scanning Electron Energy Analyzing Microscope

The display system consists of two scintillators, photomultipliers, and direct-view storage tubes; an optical superposition device with color filters; a conventional cathode-ray oscilloscope; and the associated circuitry, containing voltage supplies, amplifiers, etc. (See Fig. 6) The virtues of the system are well illustrated in use at low scattered electron intensities, whether low count rate be due to low beam strength, small beam-defining slit settings, or high energy resolution. The presentation magnification may be chosen by simple switching. Centering on the region of interest in the specimen is obtained by adjusting the dc bias voltages applied to the microscope deflection plates. Successive scans may then be piled up until visual observation indicates that a good statistical integration has been achieved for the particularly interesting region of the specimen. The recording camera may be interposed leisurely, and so may the color position device if desired, while the displays are retained in storage. The presented intensity may be adjusted for photographic ease, and additional photographs may be taken much later. Meanwhile, if the specimen contains sharp contrast edges in both directions of the microscope beam deflection plates, objective measurements may be made of the available resolution by observing signal rise time on the ordinary oscilloscope. The adjustability, versatility and convenience in using this display system have been well established with an experimental scanning microscope providing two energy-separated beams of electrons from those leaving the specimen. The general system complexity is a major disadvantage.     

损失阻抗测量装置数据采集处理系统研制

电子储存环中真空部件的损失阻抗是表征该元件性能的重要参数，该参数的测量对于真空部件的设计，性能评估都有很大的意义。介绍了合肥储存环二期工程中损失阻抗测量的研制情况。     

Fast data acquisition system based on digital oscilloscopes for fluctuation measurements in a long pulse JT-60U tokamak plasma

We have developed a new data acquisition (DAQ) system with fast sampling rate for fluctuation measurements in a long pulse JT-60U tokamak plasma. This system is based on a powerful digital oscilloscope, which has a large acquisition memory up to 50 Mwords/ch, 1 MHz sampling rate and 16 bits high resolution AD convertors. The system is composed of plural digital oscilloscopes and mass storages. On this system, most of data acquisition processes are executed at each digital oscilloscope. This feature of the system leads to an advantage that the processing loads are distributed among the digital oscilloscopes. This system has been successfully employed for measurements of various fluctuations obtained through magnetic probes, beam emission spectroscopy and so on. The size of the acquired data using this system has reached up to 10 GB/shot so far. It has demonstrated that this system is very powerful for data acquisition of multi-channeled signals with high time resolution in a long pulse plasma.     

Prompt alpha and reactivity measurements on fast metal assemblies

This paper summarizes and reviews the methods of reactivity determination and measurement of the prompt-neutron decay, briefly describes the equipment requirements for such measurements for unmoderated metal assemblies, and presents experimental results to illustrate the methods. These assemblies include fast metal critical assemblies and fast pulsed reactors. The primary reactivity determination methods used have been: (1) stable reactor period measurements which are usually used near delayed criticality to obtain the reactivity or to calibrate the reactivity prior to burst initiation; (2) prompt reactor period measurements which are useful to determine the reactivity early in superprompt critical excursions; (3) inverse kinetics rod drop measurements which obtain the reactivity as a function of time after a rod or reactor component is removed from a delayed critical assembly, and (4) prompt neutron decay constant measurements from which the reactivity can be obtained if corrections are made for changes in the neutron lifetime. Inverse kinetics and decay constant measurements are usually used below delayed criticality, although decay constant measurements have been performed above delayed critical.The decay constant is usually obtained by the traditional pulsed-neutron method, using a pulsed neutron source such as a Cockcroft-Walton accelerator, or by the Rossi-α method. The recent use of ²⁵²Cf has resulted in some new techniques for determining the decay constant and reactivity; this method has some unique advantages over the traditional methods. The theory of these new measurements is reviewed, and some recent results are presented.     

Magnbeic Recording of Neutron Cross-Section Data from an Undergrolund Nuclear Explosive Source

A high-resolution magnetic data recording system has been successfully used as part of the Los Alamos program of time-of-flight neutron cross-section measurements that use an underground nuclear explosion source. The data received were recorded in frequency modulation form on a rotating hard-surfaced magnetic disc. This is a novel way of recording these data. Magnetic recording facilitates electronic digitizing of the data, since there is no need for time-consuming film reading.     

Quality assessment system for curved crystal X-ray optics

Doubly curved crystal X-ray optics provide intense focused monochromatic beams from laboratory X-ray tube sources. These optics are employed in crystallography and X-ray fluorescence systems and may find application to imaging. It is increasingly important to understand how optic defects impact performance for these systems. A simulation model was developed to assess the effects of misalignment and optic defects on system parameters such as intensity, beam size and resolution. Simulation results were compared to optics measurements. Rapid reproducible measurements of optics quality are important both for performing systematic studies of optics defects and for assessing individual optics. A simple operator-independent alignment technique was developed that was also beneficial in ensuring optimal beam intensity in analysis systems. The measurements and simulations were in good agreement and provided insight into essential optics parameters.     

Thermoluminescence Dosimetry: Environmental Monitoring near Nuclear Reactor Sites

The application of thermoluminescence dosimetry to environmental monitoring, particularly in the vicinity of nuclear facilities, is discussed. The results of an intercomparison of TLDs and simultaneous TLD and ionization chamber measurements are presented. Techniques for interpreting measurements made in the environs of nuclear facilities are discussed and data are given demonstrating the application of these techniques for isolating exposures attributable to the operation of these facilities. The requirements of an ANSI Standard on environmental applications are summarized and the major features of commercial TLD systems discussed. Included is a short bibliography of general references, studies of the properties of phosphors and publications on the problems of environmental measurements.     

An experimental apparatus proposed for efficient removal of isobaric contaminants in negative ion beams

Isobaric contaminants are often problematical in accelerated negative ion beams for research at certain radioactive ion beam (RIB) and accelerator mass spectrometry (AMS) facilities since their presence in low-intensity rare isotopic beams seriously compromise experimental results. This article describes a non-resonant, laser-based photo-detachment apparatus for use at these facilities, which, according to calculations efficiently removes isobaric contaminants from these beams. The advantage of the system for isobaric contaminant removal over other systems proposed to date lies in its ability to efficiently capture easily transportable energetic negative ion beams with low, intermediate or high energy spreads by a superconducting solenoid magnetic field. The ability to change the diameter of captured beams by adjusting the magnetic field strength permits optimum control of the radial overlap of the laser/negative ion beam profiles over an extended interaction region under high vacuum conditions without retarding optical affect, collision-cooling or capture losses.     

Evaluations of proton inelastic mean free paths for 12 elemental solids over the energy range from 0.05 to 10 MeV

The systematical calculations of the inelastic mean free paths (MFPs) of 0.05-10 MeV protons in 12 elemental solids (Al, Si, Ni, Cu, Mo, Rh, Ag, W, Os, Ir, Pt, Au) have been performed. The calculations are based on the algorithm derived from Ashley’s optical-data model including the higher-order corrections to stopping power (SP) for protons. The prominence and necessity of the higher-order corrections are demonstrated by calculating the proton SPs for the 12 solids using Ashley’s optical-data model and by comparing the calculated SPs with the experimental results, the tabulated values and other corresponding theoretical evaluations. The algorithm of evaluating the proton inelastic MFP is described. In this algorithm, the Barkas-effect correction and the Bloch correction are taken into account, the minimum impact parameter from Lindhard is used in the Barkas-effect correction, and an empirical estimation of a free parameter involved in the Bloch correction to the inelastic MFP is proposed. The evaluated inelastic MFPs of 0.05-10 MeV protons for the 12 solids under two different cases, i.e. the higher-order corrections not being considered and the Barkas-effect correction and the Bloch correction being included, are presented in the tabulated form and are first results for these solids. These numerical results provide an alternative basic data for the Monte Carlo studies on low-energy proton transport in these 12 solids.     

Lifetime measurements using beam-foil spectroscopy

A review is presented of the current status of beam-foil lifetime measurements, with emphasis on the techniques now being used to correct for cascade effects. Examples of application of these techniques are taken from work that has appeared since the Laval Conference of 1981. The ANDC method is shown to yield generally satisfactory results for one- and two-electron systems, but further work is needed to establish the best method for more complex systems. Brief discussions are also given of recent lifetime measurements for some moderately- and highly-ionized atoms, and of very recent measurements of an autoionization rate in neutral fluorine and a magnetic-dipole transition rate in hydrogen-like argon. A short summary of recent developments in heavy metal ion sources is also presented.     

Fission Product Data Measured at Los Alamos for Fission Spectrum and Thermal Neutrons on Pu, U, U

We describe measurements of fission product data at Los Alamos that are important for determining the number of fissions that have occurred when neutrons are incident on plutonium and uranium isotopes. The fission-spectrum measurements were made using a fission chamber designed by the National Institute for Standards and Technology (NIST) in the BIG TEN critical assembly, as part of the Inter-laboratory Liquid Metal Fast Breeder Reactor (LMFBR) Reaction Rate (ILRR) collaboration. The thermal measurements were made at Los Alamos' Omega West Reactor. A related set of measurements were made of fission-product ratios (so-called R-values) in neutron environments provided by a number of Los Alamos critical assemblies that range from having average energies causing fission of 400-600 keV (BIG TEN and the outer regions of the Flattop-25 assembly) to higher energies (1.4-1.9 MeV) in the Jezebel, and in the central regions of the Flattop-25 and Flattop-Pu, critical assemblies. From these data we determine ratios of fission product yields in different fuel and neutron environments (Q-values) and fission product yields in fission spectrum neutron environments for ⁹⁹Mo, ⁹⁵Zr, ¹³⁷Cs, ¹⁴⁰Ba, ^141,143Ce, and ¹⁴⁷Nd. Modest incident-energy dependence exists for the ¹⁴⁷Nd fission product yield; this is discussed in the context of models for fission that include thermal and dynamical effects. The fission product data agree with measurements by Maeck and other authors using mass-spectrometry methods, and with the ILRR collaboration results that used gamma spectroscopy for quantifying fission products. We note that the measurements also contradict earlier 1950s historical Los Alamos estimates by ∼5-7%, most likely owing to self-shielding corrections not made in the early thermal measurements. Our experimental results provide a confirmation of the England-Rider ENDF/B-VI evaluated fission-spectrum fission product yields that were carried over to the ENDF/B-VII.0 library, except for ⁹⁹Mo where the present results are about 4%-relative higher for neutrons incident on ²³⁹Pu and ²³⁵U. Additionally, our results illustrate the importance of representing the incident energy dependence of fission product yields over the fast neutron energy range for high-accuracy work, for example the ¹⁴⁷Nd from neutron reactions on plutonium. An upgrade to the ENDF library, for ENDF/B-VII.1, based on these and other data, is described in a companion paper to this work.     

锰浴法测量中子源发射率中各修正因子的蒙特卡罗计算

在采用锰浴法对放射性同位素中子源的发射率进行测量时,MnSO₄溶液中⁵⁵Mn仅俘获部分源中子,故需考虑对未被⁵⁵Mn俘获部分的修正。用蒙特卡罗粒子输运程序MCNP对中子源强标准装置的锰浴系统进行模拟计算,对实验测量结果进行修正,并通过由国际计量局（BIPM）组织的中子源强度国际比对,验证了计算所建立模型的可靠性。利用MCNP程序的微扰计算功能,通过考虑MnSO₄溶液的密度、源及其承托物材料的密度、源的位置、锰浴半径以及反应截面的改变对计算结果的影响,对模拟计算结果的不确定度进行了详细评定,提供了一种蒙特卡罗模拟计算结果不确定度的评定方法。     

用于激光散射光测量的多路中速门控积分器研制

在VXI总线系统上研制了用于可变脉宽的信号测量的中速门控积分器。在与高速示波器比对中,两者测量结果积分非线性小于1％;现场打靶测试时,积分器最大满量程误差小于3％。     

Seismic instrumentation for nuclear power plants: An interpretative review of current practice and the related standard in Germany

The German nuclear safety standard KTA 2201: “Design of nuclear power plants against seismic events”, consists of the following parts: 1. basic principles; 2. characteristics of seismic excitation; 3. design of structural components; 4. design of mechanical and electrical parts; 5. seismic instrumentation; and 6. measures subsequent to earthquakes.While Part 1 was published in June 1975, Part 5 was approved by the Nuclear Safety Standards Commission — Kerntechnischer Ausschuss (KTA) — in June 1977. The other parts are still under development. The requirements of the safety standard KTA 2201.5 deal with

1. (a) number of location (number and location of acceleration recording systems for different sites, single-block plants and multi-block plants);

2. (b) characteristics of instruments (readiness and operation of instruments, margin or errors, dynamic and operation characteristics, duration of records, seismic switch);

3. (c) triggering and information (loss of electric power, start of the acceleration recording systems, threshold of acceleration for triggers and seismic switches, optical and acoustic information); and

4. (d) documentation (results of recordings, inspection and tests).

The purpose of this paper is to present some detailed requirements of the safety standard KTA 2201.5, with its philosophy, and compare these with corresponding requirements in the US. It will be shown that with relatively few instruments, which are very reliable in operation and in triggering, an optimum of data may be available after an earthquake.     

A Digital Optimalization Device for Directional Charged Particle Measurements in Space Research

A method is described which allows for synchronisation of periodically repeated spinsynchronous measurements with the spin-independent data readout cycle. The method is selfadapting insofar, as it adjusts itself to any spinrate, which the spacecraft may acchieve. Permanent lock relative to the sun allows for directional measurements of particle fluxes in a coordinate system fixed relative to the sun without additional corrections.     

示波器嵌入式IOC研制及应用

宽带束流信号的量化和处理是加速器柬流诊断中的常见问题,上海光源束测组针对此应用开发出了示波器嵌入式IOC作为专用的束流信号处理器.该解决方案在EPICS构架的控制系统中具有即插即用的特点,目前已在上海光源注入器束团流强测量系统以及储存环填充模式测量系统中投入实用.本文介绍了部分宽带束流的测试结果.     

DSP Oscilloscope for HVDC Fault Testing System

Due to frequently occurring vacuum sparking in the accelerators, snubber is used to limit the fault arc current to improve the International Thermonuclear Experimental Reactor safety. In this paper, a two-channel impulse automatic digital oscilloscope, based on field programmable gate array and digital signal processing (DSP), is designed to automatically measure fault arc current and voltage which exist in snubber-implemented high voltage direct current (HVDC) circuit whose fault can destroy many crucial components of the magnetic confinement fusion device. Experimental results from both 12 V low voltage direct current and 120 kV HVDC show that this DSP oscilloscope is stable, reliable, fully automatic, and can function well under strong electromagnetic interference conditions, which fully meet the experimental requirements.     

Nuclear data sheets for A = 206

Nuclear structure data available through July 1978 for nuclei with mass number 206 are compiled and evaluated. A summary of the information obtained in reaction and decay measurements is presented with the bulk of the data being presented pictorially for easy comparison. Adopted level and decay properties are given. Any additions or corrections should be addressed to the evaluators for maintenance and updating of the data file.     

暗物质测量实验中基于ROOT的探测器数据获取系统

描述了用于超低能高纯锗探测器实验的数据获取（DAQ）系统,该实验用于对WIMP粒子在质量100GeV／c^2以下,特别是低于10GeV／c^2范围内的探寻。DAQ系统采用一台四通道数字化示波器,同时读取来自高纯锗探测器和反康普顿谱仪CsI（T1）晶体探测器的数据。基于ROOT的数据获取程序把数据存为特定的格式。整套系统已稳定运行了数月。随着实验数据的积累,实验运行参数的优化工作即将展开。