A neutron field monitoring system for collider experiments

A monitoring system for intense (up to 10⁵ neutrons/(cm² s)) neutron fluxes with energies as high as 15 MeV has been developed for long-term operation in strong magnetic and radiation fields of collider experiments. The system is used to monitor the radiation shielding efficiency, estimate the radiation degradation of active elements of experimental setups, and perform additional independent monitoring of the accelerator luminosity. The system has been tested and put into operation at the Compact Muon Solenoid (CMS) experimental setup of the Large Hadron Collider (LHC).     

A gated liquid-scintillator-based neutron detector for fast-ignitor experiments and down-scattered neutron measurements

The detection of neutrons in fast-ignitor experiments or down-scattered neutrons in inertial fusion experiments is very challenging since it requires the neutron detection system to recover within 10-100 ns from a high background orders of magnitude stronger than the signal of interest. The background is either the hard x-ray emission from short-pulse laser target interactions for the fast-ignitor experiments or the primary neutron signal for the down-scattered neutrons. A liquid-scintillator detector has been developed using a gated photomultiplier that suppresses the background signal and eliminates the afterglow present in conventional plastic scintillators.     

一种新型即时功率模块设计

介绍了一种低成本,且可以达到较高的采样速度要求和精度要求的功率模块的设计方案。在阐述方案的同时介绍了模块具备的电磁阀动作测量功能和模块与上位机之间基于RS-485串行总线通讯的实现。经过实践验证,该方案开发的模块在实际应用中具有很高的稳定性和良好的应用前景。     

A Freon-filled bubble chamber for neutron detection in inertial confinement fusion experiments

Neutron imaging is one of the main methods used in inertial confinement fusion experiments to measure the core symmetry of target implosions. Previous studies have shown that bubble chambers have the potential to obtain higher resolution images of the targets for a shorter source-to-target distance than typical scintillator arrays. A bubble chamber for neutron imaging with Freon 115 as the active medium was designed and built for the OMEGA laser system. Bubbles resulting from spontaneous nucleation were recorded. Bubbles resulting from neutron-Freon interactions were observed at neutron yields of 10(13) emitted from deuterium-tritium target implosions on OMEGA. The measured column bubble density was too low for neutron imaging on OMEGA but agreed with the model of bubble formation. The recorded data suggest that neutron bubble detectors are a promising technology for the higher neutron yields expected at National Ignition Facility.     

A water monitoring system with a submersible module

The water monitoring system with a submersible module is intended for performing long-term measurements of concentrations of chlorophyll “A” and colored dissolved organic matter (CDOM) at different depths by the laser-induced fluorescence method. The special feature of the system is the use of a fiberoptic fluorescence sensor in the submersible module, which allows one to perform measurements in a wide wavelength range. The article describes the main units of the system and its operation algorithm. The fluorescence signal processing technique is presented. The measurement results obtained by using the monitoring system are compared with those obtained by narrow-band fluorometric sensors (WETLabs, USA).     

A high-voltage system of a differential spectrometer for measuring the neutron electric dipole moment

A system of hardware and software for supplying a bipolar high voltage of up to 200 kV to a differential spectrometer that measures the neutron electric dipole moment is described. The high-voltage source is based on two 10-cascade voltage multipliers using quasi-resonant technology. The hardware and application software allow operation of the system in the manual, semi-automatic, and automatic modes.     

An automation system for experiments with a neutron powder diffractometer

The modernization of the detector system and control system of the neutron powder diffractometer (NPD) in the GEK-5 channel of the VVR-c reactor (Obninsk Branch, Karpov Institute of Physical Chemistry) is described. The PC-connected hardware and software complex, which ensures data acquisition and storage and control of the experiments, is created. The main modules of the NPD automation system and Sonix+ control software package, designed at the Frank Laboratory of Neutron Physics at JINR, are briefly described. The modernization has made it possible to increase the luminosity of the diffractometer and completely automatize the measurement process.     

A method of measuring the neutron energy spectrum by activation detectors

This work is a preliminary step toward the study of physical properties of the ADS systems, in which a deeply subcritical active core is irradiated by a pulsed beam of relativistic deuterons.This work analyzes a general direct method of calculating a neutron energy spectrum using efficiency of reactions of activation detectors. Our interest was focused on the study of the influence of input experimental errors and uncertainty of cross sections on output errors. The experimental data are taken from the KWINTA experiment in JINR, Dubna. The obtained results of the neutron flux spectrum in range 0.7–200 MeV are compared with calculation results from the MCNPX code.     

Fusion neutron detector for time-of-flight measurements in z-pinch and plasma focus experiments

We have developed and tested sensitive neutron detectors for neutron time-of-flight measurements in z-pinch and plasma focus experiments with neutron emission times in tens of nanoseconds and with neutron yields between 10(6) and 10(12) per one shot. The neutron detectors are composed of a BC-408 fast plastic scintillator and Hamamatsu H1949-51 photomultiplier tube (PMT). During the calibration procedure, a PMT delay was determined for various operating voltages. The temporal resolution of the neutron detector was measured for the most commonly used PMT voltage of 1.4 kV. At the PF-1000 plasma focus, a novel method of the acquisition of a pulse height distribution has been used. This pulse height analysis enabled to determine the single neutron sensitivity for various neutron energies and to calibrate the neutron detector for absolute neutron yields at about 2.45 MeV.     

智能变压器绕组热点温度监测仪

本文介绍了一种新型油浸式电力变压器绕组热点温度在线监测仪。该监测仪实时采集变压器负荷电流和变压器顶层和底层油温,依据国际电工技术委员会推荐的油浸式电力变压器绕组热点计算公式,实时监测绕组热点温度。文中介绍了监测仪的测量原理及硬件电路和软件流程,给出使用后的数据记录。结果表明,该监测仪的稳定性与精度均满足现场测试要求。     

Development and application of setup for ac magnetic field in neutron scattering experiments

We report on a new setup developed for neutron scattering experiments in periodically alternating magnetic fields at the sample position. The assembly consisting of rf generator, amplifier, wide band transformer, and resonance circuit. It allows to generate homogeneous ac magnetic fields over a volume of a few cm(3) and variable within a wide range of amplitudes and frequencies. The applicability of the device is exemplified by ac polarized neutron reflectometry (PNR): a new method established to probe remagnetization kinetics in soft ferromagnetic films. Test experiments with iron films demonstrate that the ac field within the accessible range of frequencies and amplitudes produces a dramatic effect on the PNR signal. This shows that the relevant ac field parameters generated by the device match well with the scales involved in the remagnetization processes. Other possible applications of the rf unit are briefly discussed.     

一种新型电能质量在线监测装置

随着信息技术的发展,电能质量日显重要,但实际中电力部门又往往对电能质量缺乏有效的在线监测手段以及对电能质量部分暂态干扰指标的监测不全面。文中介绍了一种全新原理的电能质量在线监测装置,可以彻底解决这个问题。     

基于无线模块的反应釜清洗头实时监测系统

为了解决化学工业反应釜清洗工况的安全生产问题,研制了清洗头实时监测系统。针对国外原方案中传感器容易挂料且难以清理的缺点,采用加速度传感器监测釜体表面振动信号,通过信号的相关分析,实时监测清洗头工作情况,解决了传感器挂料对监测可靠性的影响。在信号传输中采用无线信号模块代替原有有线电缆的连接,减少了复杂工业现场的连线成本,提高了可靠性。     

摩托车曲轴组件动平衡检测新方法的研究

本文介绍了一种新型的摩托车曲轴组件动平衡检测系统的测量方法和结构.不平衡曲轴组件转动产生的惯性离心力引起振动台振动,安装在振动台上的振动传感器拾取振动信号,送至计算机.通过信号处理得到曲轴组件的不平衡量.本系统在LabVIEW平台上开发了虚拟仪器,实现了数据采集、数据处理以及分析自动化.实验结果表明,本系统具有精度高、检测效率高、制造成本低的优点.     

Development of the large neutron imaging system for inertial confinement fusion experiments

Inertial confinement fusion (ICF) requires a high resolution (~10 μm) neutron imaging system to observe deuterium and tritium (DT) core implosion asymmetries. A new large (150 mm entrance diameter: scaled for Laser Me?gaJoule [P. A. Holstein, F. Chaland, C. Charpin, J. M. Dufour, H. Dumont, J. Giorla, L. Hallo, S. Laffite, G. Malinie, Y. Saillard, G. Schurtz, M. Vandenboomgaerde, and F. Wagon, Laser and Particle Beams 17, 403 (1999)]) neutron imaging detector has been developed for such ICF experiments. The detector has been fully characterized using a linear accelerator and a (60)Co γ-ray source. A penumbral aperture was used to observe DT-gas-filled target implosions performed on the OMEGA laser facility. [T. R. Boehly, D. L. Brown, R. S. Craxton, R. L. Keck, J. P. Knauer, J. H. Kelly, T. J. Kessler, S. A. Kumpan, S. J. Loucks, S. A. Letzring, F. J. Marshall, R. L. McCrory, S. F. B. Morse, W. Seka, J. M. Soures, and C. P. Verdon, Opt. Commun. 133, 495 (1997)] Neutron core images of 14 MeV with a resolution of 15 μm were obtained and are compared to x-ray images of comparable resolution.     

Real time in situ ellipsometric and gravimetric monitoring for electrochemistry experiments

This work describes a new system using real time spectroscopic ellipsometer with simultaneous electrochemical and electrochemical quartz crystal microbalance (EQCM) measurements. This method is particularly adapted to characterize electrolyte/electrode interfaces during electrochemical and chemical processes in liquid medium. The ellipsometer, based on a rotating compensator Horiba Jobin-Yvon ellipsometer, has been adapted to acquire Psi-Delta spectra every 25 ms on a spectral range fixed from 400 to 800 nm. Measurements with short sampling times are only achievable with a fixed analyzer position (A=45 degrees ). Therefore the ellipsometer calibration is extremely important for high precision measurements and we propose a spectroscopic calibration (i.e., determination of the azimuth of elements according to the wavelength) on the whole spectral range. A homemade EQCM was developed to detect mass variations attached to the electrode. This additional instrument provides further information useful for ellipsometric data modeling of complex electrochemical systems. The EQCM measures frequency variations of piezoelectric quartz crystal oscillator working at 5 MHz. These frequency variations are linked to mass variations of electrode surface with a precision of 20 ng cm(-2) every 160 ms. Data acquisition has been developed in order to simultaneously record spectroscopic ellipsometry, EQCM, and electrochemical measurements by a single computer. Finally the electrodeposition of bismuth telluride film was monitored by this new in situ experimental setup and the density of electroplated layers was extracted from the optical thickness and EQCM mass.     

Angular correlations in detection of α-γ coincidences in the nanosecond tagged neutron technology

The characteristics of the setup for analyzing the elemental composition of organic substances using spectroscopy of γ rays induced by tagged neutrons with an energy of ～14 MeV in an inelastic neutron scattering reaction are discussed. An ING-27 D-T neutron generator with a built-in position-sensitive α detector, fast neutron and γ detectors, and a multichannel detecting system providing a subnanosecond time resolution are parts of the experimental setup. The correlation between the exit angle of a neutron and the number of the α pixel, as well as the anisotropy in emission of γ rays in the inelastic neutron scattering reaction, are measured, and the errors of these measurements are estimated.     

The time characteristics of a single module of the neutron detector

The time characteristics of the scintillation plate that is an element of the neutron detector designed for measuring the energy of a neutron by its time of flight and determining the coordinate of the point of its interaction with the detector have been investigated on cosmic rays. The time resolutions of the neutron detector element measured with P9814B and FEU-63 photomultiplier tubes are σ ≈ 0.14 and 0.29 ns, respectively.     

VOCs在线监测系统多点自动校准开发与应用

随着VOCs在线监测系统的广泛应用,环保部门加强了对监测系统的运维要求,提出了系统自动校准功能的明确需求。本文介绍了用于VOCs在线监测系统的多点自动校准,实现了在应用现场标气浓度自动配比、标气预警以及自动完成定期单点、多点校准功能。通过实际检测,多点自动校准系统的标气浓度配比稳定性高,系统监测标气测量值与实际值的示值误差为0.1mg/m 3,准确度为0.08%,自动校准后的系统24小时、48小时、72小时的数据线性度R 2大于0.9996。本方法在工程应用中有实用性。     

体内检测数字电路CMOS发射模块设计研究

介绍体内检测信号传输方面的研究。分析数字静像拍摄和发射部分设计计算的技术要点。从照明亮度设计、控 制CPU、RF发射单元设计、系统程序设计和功率匹配设计等方面对数字电路CMOS发射模块进行了设计。