Generators of nanosecond intervals

Block diagrams of two high-stability scanning time-interval generators that can be used to automate tuning and testing of relative-time actuation channels in particle detectors are described. The first generator has the following performance characteristics: an operation range of 0–255 ns, a scan step of 1 ns, and a maximum error of ±0.5 ns. This error remains unchanged within the time of a single scan. The second generator has two operating modes. In the first one (the scan mode), it has an operation range of 50–3000 ns and a scan step of 50 ns. In the second mode, with fixed duration of time intervals, it has an operation range of 50–12 750 ns that can be changed with an increment of 50 ns. The relative error in the duration of the generated interval is 10^?5 s.     

A Time-To-Digital Converter with a Resolution of 2 ns

A CAMAC (1M) single-channel time-to-digital converter has been designed for measuring time intervals with a time resolution of 2 ns in the range from 0 to ~131 μs. This range can be extended by connecting an additional external counter. This converter is of the counting-pulse type with a calibrated conversion scale. A recirculation generator based on a K500LM101 chip is used as a source of counting pulses. One time interval can be measured at once. Several time-to-digital converters can be combined into a multistop measuring system to increase the number of time intervals recorded by a single Start signal. The differential nonlinearity is 1%, and the integral nonlinearity in the above range is 0.001%. The relative instability of the conversion coefficient caused by supply-voltage variations within the range of–6 V ± 2.5% is 0.24%. The temperature drift of the conversion coefficient in the temperature range of 22.6–65.7°C is 0.07%/°C.     

多通道门选通纳秒分幅相机

采用光学分幅技术和多通道门选通法研制了纳秒分幅相机。首次应用八棱锥将图像分为8幅,每幅图像有相等的光学能量并包含与原图像相同的光学信息,每个通道使用独立的带门选通的像增强器和CCD相机,自行开发的近贴门选通像增强器用于增强弱光图像。相机系统可一次获得8幅图像,分幅速率达到1×10⁸ frame/s,最短曝光时间和时间间隔为3 ns和10 ns并分别可调,可记录持续时间为百纳秒到几十微秒的发光现象,动态空间分辨率达到15 lp/mm。该相机已成功应用于电脉冲、等离子发光等现象的试验并获得了有意义的数据,可满足高速摄影机等设备具有高分幅速率,短曝光时间和适当间隔以及在曝光时间内固定时刻记录超快现象过程的要求。     

High resolution heterodyne interferometer based on time-to-digital converter

A new heterodyne interferometer is presented, which adopts time-to-digital converter (TDC) measuring the time intervals of zero crossings of heterodyne signal for phase demodulation. Thanks to the 0.1 ns time resolution of TDC and linear phase demodulation, it can achieve high resolution and avoids nonlinear measuring distortion in other indirect high precise phase demodulation methods, such as pulse width modulation (PWM) and in-phase∕quadrature (I∕Q) method.     

Relationships between the electrocardiogram and phonocardiogram: potential for improved heart monitoring

Improvements in current heart monitoring techniques could reduce the number of heart attacks and resulting deaths. The potential for using time intervals measured between waveforms of the electrocardiogram (ECG), phonocardiogram (PCG), and peripheral blood flow pulse (PP) for heart monitoring was studied. The waveform locations identified in the simultaneously recorded signals included the R- and T-wave peaks of the ECG, the first (S1) and second (S2) sounds of the PCG, and the systolic peak of the PP. The signals were found to be highly consistent from one cardiac cycle to the next. Further, the time intervals measured between the different signals were stable with time. Strong relationships were found between the intervals R to T and R to S2 and the R to R interval. In contrast, R to PP and R to S1 correlated poorly with the R to R but strongly with each other. Additional differences between the measured intervals were revealed by studying changes due to exercise and different body positions. The relationships between the measured intervals were found to be independent of PCG recording location. This study demonstrates the feasibility and potential of using the electrical-contractile indices of heart function for monitoring heart patients. Design of a computer-based monitor using the techniques specified in this study is discussed along with relative strengths and weaknesses of such a system.     

Design and Development of a Miniature Digital Delay Generator for Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is widely used for atomic emission spectroscopy. The delay time is a significant factor that affects the selection of the optimal plasma conditions. In this study, a miniature digital delay generator was designed and built for time-resolved LIBS with a widely adjustable time delay with 0.1 ns resolution. Experimental observations were used to examine and perform a diagnosis study of the delay time accuracy and a series of time-resolved LIBS spectra with satisfactory signal-to-noise ratios were obtained. Therefore, this delay generator is suitable for replacing the widely used delay generators in LIBS instrumentation and may have widespread application in portable instrumentation.     

Processing of the signals from the liquid-xenon calorimeter of the CMD-3 detector for timing measurements

Detecting near-threshold nucleon production reactions is one of the tasks that must be performed by the CMD-3 cryogenic magnetic detector operating at the Budker Institute of Nuclear Physics. Events of neutron-antineutron pair production, followed by antineutron annihilation, are detected by the detector calorimeters. The energy range differing by ∼25 MeV from the nucleon-producing threshold is the most interesting region for studying such events. At energies such as these, antineutrons annihilate in a cylindrical liquid-xenon calorimeter ≥5 ns after the beams collide. For reliable identification of these events, it is necessary that the flight time of these particles to the calorimeter be determined with an accuracy of 3 ns or better. The calorimeter is composed of a set of ionization chambers with the anode and cathode readout. The time of charge collection from the anode cells is 4.5 μs. Therefore, for the instant when a signal appears in the calorimeter to be determined with a required accuracy, a special signal processing method has been developed, with which it is possible to measure the arrival time of the calorimeter signals with the required accuracy in the real time mode. The prototype of the developed measuring channel has been tested. The test results basically satisfy the requirements: for the arriving signal equivalent to the deposited energy of 200 MeV, the measured time resolution is 3.1 ns, which is close to the calculated value of 2.9 ns.     

Temporal characteristics of light collection in the liquid scintillation counter with a volume of 1.5 m<Superscript>3</Superscript> and quasi-mirror reflection

The temporal behavior of light collection in the 1.5-m³-volume mirror-reflecting counter filled with a highly transmitting liquid scintillator has been investigated. Using the Monte Carlo method and assuming that the luminescence decay time of the liquid scintillator is zero (τ_LS = 0), it has been ascertained that, in the case of a short flash in a counter, the exponential phase of light collection is characterized by time τ_col = 15.0 ± 1.7 ns, which is does not depend on scattering of light in the medium. The measured exponent index τ_act = 37 ± 3 ns of an actual pulse due to a muon is determined both by light collection time τ_col ≈ 15 ns and luminescence decay time τ_LS ≈ 20 ns of the scintillator in the large-volume counter.     

An interpolating time-to-digital converter on an FPGA

A simple and sufficiently precise unit converting single time intervals to digital codes on an EP2C20F484C7N Altera field programmable gate array is proposed. The resolution of the converter, the principle of operation of which is based on interpolating the reference period by a great number of outputs of a ring pulse oscillator, is determined by the delay time of the oscillator stage and is 315 ps. The converted interval range is 2.58 μs, and the “dead” zone between adjacent conversions does not exceed 5 ns. The circuit does not need any adjustments and is insensitive to supply voltage and environment temperature deviations.     

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.     

A new hybrid parallel algorithm for consistent-sized batch splitting job shop scheduling on alternative machines with forbidden intervals

Considering alternative machines for operations, forbidden intervals during which machines cannot be available and a job’s batch size greater than one in the real manufacturing environment, this paper studies the batch splitting scheduling problem on alternative machines with forbidden intervals, based on the objective to minimize the makespan. A scheduling model is established, taking before-arrival set-up, processing, and transfer time into account. And a new hybrid parallel algorithm, based on differential evolution and genetic algorithm, is brought forward to solve both the batch splitting problem and the batch scheduling problem by assuming a common number of sub-batches in advance. A solution consists of the actual optimum number of sub-batches for each job, the optimum batch size for each sub-batch, and the optimum sequence of operations for these sub-batches. Experiments on the performance of the proposed algorithm under different common numbers of sub-batches are carried out. The results of simulations indicate that the algorithm is feasible and efficient.     

A ГИН-1200 high-voltage pulse generator

The electric circuit, design, and electric and triggering characteristics of the ГИН-1200 small-sized 12-stage high-voltage pulse generator used for charging a double forming line to 1 MV for a 300-ns period are described. The generator is mounted in a metallic housing with the transformer-oil insulation. The storages in stages of the generator are KMK 100–0.017 (100 kV, 0.017 μF) capacitors with a 1-kJ total stored energy. The switches are trigatron gaps filled with a 20% SF₆ + 80% N₂ gas mixture. The gap housings are assembled into one line. The through-passing axial channel ensures spark illumination of adjacent intervals, thereby improving the triggering characteristics of the generator. The operation-time scatter of the ГИН-1200 generator at an 85-kV charging voltage and 65% electric-strength margin was ≤10 ns, and the operation delay time was ～100 ns. The ГИН-1200 generator operated ～2000 times and demonstrated reliable stable operation.     

A wide-range time-digital converter

A time-digital converter is designed for studying events with long delay times between events, which are correlated in time. The measured time interval range is 276 μs, the converter channel width is 67.4 ns, the integral nonlinearity is ≤1%, and the differential nonlinearity is ≤4%. The converter is made in the CAMAC standard.     

多通道高精度时间-数字转换器的研制

介绍了一种基于USB2.0接口的多通道高精度时间 数字转换器(time-to-digital converter, TDC)的设计与实现。完成了NIM-LVPECL电平转换电路、高速串并转换电路、基于FPGA的数据处理及相关逻辑控制等单元电路的设计,最后给出了TDC的测试性能指标。结果表明,TDC的最小时间分辨率为403 ps,测量时间范围为0~420 us,测量“死时间”<13 ns。TDC可广泛应用于高精度的时间间隔测量领域,特别是作为飞行时间质谱仪（time-of-flight mass spectrometer, TOF-MS）的数据采集卡。     

Traceability of pulsed flow rates consisting of constant delivered volumes at given time interval

Very low flow calibrations are important in several areas of pharmaceutical, microfluidic and health care applications where volumetric dosage or delivery at given flow rates are crucial for the process. Not only constant and steady flow rates are commonly used in the health sector, but also pulsed flow rates consisting of constant delivered volumes at given time intervals. One known application is the delivery of Insulin with tethered or patch pumps. These constant volumes can be in the order of several tens or hundreds of nanoliters. As the delivery times can vary up to several minutes, it is not appropriate to determine an average flow rate of the delivered volume. It is more advisable to determine the average volume and the average time interval of delivery.The METAS Microflow facility has been upgraded to perform measurements with insulin pumps delivering a volume of 500 nL at a given time interval of several minutes. The updated design and new aspects of the discontinuous volume collection from the tethered or patch pumps are discussed in this paper. First calibration results of insulin pumps are also presented.     

抽样定理在周期性非连续信号的压电泵气穴现象中的应用方法

抽样时间间隔由抽样定理来决定.压电泵气穴现象所摄取的连续画像也应遵从该定理来抽取得到不连续的静止画像.可是,作为由振动形式驱动的压电泵,气穴现象只发生在吸入工程,了解其气穴现象统计特性时,如果按着抽样定理,在吐出工程的半周期,即使是不发生气穴现象也必须依次抽样.若利用这样的数据系统,数据的样本将过大,对其解析的时间性与经济性均不利.而且,在吐出工程的半周期,是与气穴无关系的信号.因此对于气穴现象数据系统,可以说是输入了错误情报信号.为此,开发了适用于压电泵气穴现象周期性非连续信号的抽样定理的方法;同时,利用这个方法,以有阀压电泵为例,调查了该泵的气穴现象特性之一的中心多发性,发现里利用新方法测得的中心多发几率高于原方法.     

起重机用减速器承载能力和选用方法探讨

本文对起重机减速器的承载能力和选用方法的分析表明,工作级别Ｍ１－Ｍ８中,其相邻级别按１．１２的比例折算功率稍大但比较接近于理论值,把Ｍ５的额定功率确定为连续工作状况的２倍则与理论值相差过大,因此,硬齿面齿轮减速器没有必要再去划分工作级别,通用的选用２方法同样适用于志重机减速器的选用。     

Single electron response of the scintillator-light guide-photomultiplier detector

The time response of a scintillator-light guide-photomultiplier combination was measured with a time-constant of 3 ns. Single detected electrons were recognizable at the output of the photomultiplier. The distribution of the number of photoelectrons produced by one detected electron and the pulse-height distribution of the photomultiplier output pulses were analysed. Statistical noise computed from these distributions was compared with the noise produced by the dark current of the photomultiplier.     

RESPONSE TIME MEASURING SYSTEM FOR ORGANIC ELECTROLUMINESCENT DEVICES

In order to analyze the optoelectrical characteristics of organic electroluminescent (OEL) devices, a response time measuring system was established. This system contains a brightness detector with a fast response photoamplifer tube (PMT), a power supply, and a PC computer with an ultra-fast data collection card. The fast response data collection card installed in the PC computer controls the entire course of measurements. The power supply applies a constant voltage to the brightness detector and a pulse voltage to the OEL device to enable it to emit light. The brightness detector receives the light emitted from the OEL device. Both the brightness and driving voltage signals are transferred directly to the computer. Then the voltage-time and brightness-time curves are simultaneously recorded and, finally, the device response time is easily obtained from these curves. The lowest response time of this system that can be measured is 50 ns. With this system, the response times of the OEL devices driven by different voltages have been measured.     

An instability estimation of precision time intervals

A method for estimating the instability of time intervals (TIs) is described, when they are measured simultaneously (in parallel) by two measuring units. The method is based on the calculation of the covariance of parallel measurement results and statistical averaging and is intended to investigate instabilities in picosecond and subpicosecond ranges. The relative error of the method is estimated by a computing experiment and depends on the amount of the measured data and error values of the used TI meters. An example of the setup, which allows one to evaluate the TI instability up to 0.4 ps with a relative error of no more than 10%, is given. The experimental data on the TI instability in the picosecond (for AFG3252 two-channel generator, it varies from 2.4 to 5.2 ps for intervals of the microsecond range) and subpicosecond (for the TI generator based on a quartz voltage-controlled oscillator from the FORDAHL company, it is 0.86 ps) ranges are obtained.