High-speed Digital Oscilloscope Research Articles

Neutron-gamma separation study for ZnS(Ag)/6LiF scintillator and silicon photomultipliers

Registration of thermal neutrons while simultaneously suppressing or rejecting accompanying gamma-ray background is an important task for many fields. We report on two different experimental neutron-gamma separation studies, utilizing a ZnS(Ag)/6LiF scintillator and pulse height discrimination technique: one is a comparison of the responses of a ZnS(Ag)/6LiF scintillator and a ‘reference’ GAGG(Ce) scintillator when irradiated by gamma sources 137Cs and 241Am; and the second is testing a dual readout, where a photosensor coupled to the ZnS(Ag)/6LiF scintillator screen on each side was irradiated by neutrons (252Cf neutron source). For all measurements the silicon photomultipliers (SiPMs) PM3315-WB-A0 (3x3 mm2 sensitive area, 15 μm cell pitch) manufactured by KETEK were used as a photosensor. High-speed digital oscilloscope LeCroyWR 620zi with a sample rate of 10 GS/s was used as a data acquisition system.

Experimental comparison of the measurement results of two different silicon photomultipliers and organic scintillator to detect fast neutrons

We report on the study of experimental comparison between the results of two types of silicon photomultiplier (SiPM), to discriminate the signals from fast neutrons and gamma-rays by the digital charge pulse shape discrimination (PSD) method. This uses a total to partial charge ratio analysis. The signals are digitized by a high-speed digital oscilloscope LeCroy WR 620zi with a sample rate of 10 GS/s. This oscilloscope was used to acquire data, which were later processed offline in a specially developed software package written in LABVIEW. The tested detector part consisted from a stilbene crystal (3x3x6 mm3 and 6x6x6 mm3) optically coupled to a SiPM (KETEK 3x3 mm2 and SensL 6x6 mm2 respectively) as a photodetector. Measurements with a Cf-252 source were performed and a figure of merit (FOM) for discrimination between neutron and gamma-ray was calculated for each assembly. The resulting value of FOM for the KETEK 3x3 mm2 SiPM and SensL 6x6 mm2 SiPM was 1.6±0.03 and 1.76±0.05, respectively, the SensL assembly having a slightly better discrimination factor than KETEK one. The obtained results prove a good fast neutron detection performance of the SiPMs, which makes it possible to use these types of neutron detectors in the several fields of radiation protection applications and safety of nuclear facilities.

Metal transfer of aluminum alloy double-wire pulsed GMAW with a median waveform

Abstract This paper proposes a double-wire pulsed gas metal arc welding (GMAW) process with a median current waveform based on traditional double-wire pulsed GMAW. A high-speed digital camera and digital oscilloscope were used to simultaneously record the metal transfer process as well as the voltage and current waveforms under different median currents. The median pulse was modeled as an exponential function and a mathematical model of the droplet diameter was established. Further, variation of the output current during the welding process and the influence of pulse parameters on the metal transfer process were accurately described. The results show that the median current has a significant impact on the metal transfer process. When the median current increases, the metal transfer period gradually decreases and the desired one drop per pulse (ODPP) mode, with a moderate droplet size and no droplet collision, is almost achieved within an appropriate median current range. As the median current gradually increases, the droplet diameter also increases but then begins to decrease as the median current further increases and gets closer to the peak current. The droplet offset distance first decreases considerably, then begins to increase, and droplet collision occurs as the median current continues to increase, resulting in an unstable transfer process. Initially, the transfer time decreases and then increases, followed by a subsequent decrease as the median current continues to increase.

Source Diagnosis Method for Radiated EMI Noise Based on Wavelet and ICA Strategy

In this paper, the independent component analysis (ICA) algorithm, combined with wavelet algorithm, are introduced to diagnose the radiation noise source, also to segregate various radiation noise components. The nonlinear time domain signals of supeposed rradiation noises are measured using multi-channel high-speed digital oscilloscope. Double frequency domain analysis of radiation noise are conducted with the proposed method. Furtherly, time-frequency joint graph of excessive radiation noise are accessed, according to overclock points. The radiation noise component is determined by employing signal separation algorithm. The effective diagnosis of common frequency radiation noise is thus realized, which contributes to reducing the radiated noise electronic device emitted.

Digital pulse shape discrimination technique for liquid scintillation detector EJ-301

A digital pulse shape discrimination (PSD) system has been built using a high speed digital oscilloscope NI-5772 and tested with an EJ-301 liquid scintillation detector. The sampling frequency of this system is 1.6 Gs/s. In this work, the charge comparison method, the rise time method and the zero-crossing time method are used to perform neutron-gamma discrimination. Experimental results show that the studied digital PSD algorithms can discriminate neutron and gamma rays in mixed radiation fields. The digital rise time method shows the optimal neutron-gamma discrimination with integration parameter RC of 10000 ns. Moreover, the zero-crossing time method is investigated through CR-R1C1 and CR-R1C1-R2C2 shaping networks. It is found that for the same pair of values for the two kinds of network, the CR-R1C1-R2C2 shaping network presents better neutron-gamma discrimination with R2C2 of 5 ns. In addition, through the investigation of the distribution of neutron and gamma peaks for different energy regions, the relationship between the ionization density of liquid scintillation detector and the contribution of slow component in the light outputs is demonstrated.

Improving characterization capabilities in new single-photon avalanche diode research.

Many novel and promising single-photon avalanche diodes (SPADs) emerged in recent years. However, some of them may demonstrate a very high dark count rate, even tens of megahertz, especially during the development phase or at room temperature, posing new challenges to device characterization. Gating operation with a width of 10 ns can be used to suppress the dark counts not coincident with the photon arriving time. However, as a side effect of the fast-gating operation, the gating response could be much higher than the avalanche signal and is usually removed by various circuit-based cancellation techniques. Here, we present an alternative method. A high-speed digital storage oscilloscope (DSO) is used to extract the weak avalanche signals from the large gating response background by waveform subtraction in software. Consequently, no complex circuit and precise tuning for each SPAD are needed. The avalanche detection threshold can be reduced to 5% of the full vertical scale of the DSO or 5 mV, whichever is greater. The timing resolution can be better than 2 ps for typical avalanche signals. Optical alignment and calibration are easy. The feasibility of on-wafer test with an RF probe station is discussed. All the advantages and features listed above make this method very useful in new SPAD research.

Low power radiometric partial discharge sensor using composite transistor-reset integrator

The measurement of partial discharge provides a means of monitoring insulation health in high-voltage equipment. Traditional partial discharge measurements require separate installation for each item of plant to physically connect sensors with specific items. Wireless measurement methods provide an attractive and scalable alternative. Existing wireless monitoring technologies which use time-difference-of-arrival of a partial discharge signal at multiple, spatially separated, sensors place high demands on power consumption and cost due to a requirement for rapid sampling. A recently proposed partial discharge monitoring system using a wireless sensor network and measuring received signal strength only, has potential cost and scalability advantages. An incoherent wireless sensor incorporating a transistor-reset integrator has been developed that reduces the measurement bandwidth of the PD events and alleviates the need for high-speed sampling. It is based on composite amplifier techniques to reduce the power requirements by a factor of approximately four without compromising precision. The accuracy of the proposed sensor is compared to that obtained using a high-speed digital sampling oscilloscope. Received energies were measured over a 10 m distance in 1 m increments and produced an error within 1 dB beyond 4 m and 3.2 dB at shorter distances, resulting in a measurement accuracy within 1 m.

Demonstration of Millimeter Wave 5G Setup Employing High-Gain Vivaldi Array

We present a 4 × 4 slot-coupled Vivaldi antenna (SCVA) array unit cell, which offers wide bandwidth and high gain (~23 dBi) at the millimeter wave (mmW) frequencies of 28 GHz and 38 GHz. A single SCVA element is first presented, which has a bandwidth of 25–40 GHz with an average gain of ~13 dBi at the frequencies of interest. This antenna element is then used to design a 1 × 4 linear SCVA array matched to a 50 Ω impedance via a modified Wilkinson power divider (WPD). Next, the 1 × 4 linear array is used to construct a 4 × 4 antenna array unit cell. The proposed 4 × 4 antenna array unit cell is fabricated, and the characteristics of its elements (i.e., the single SCVA, 1 × 4 linear array, and WPD) are thoroughly investigated. Further, the 4 × 4 array is tested for signal reception of various digital modulation formats at lab environment using high-speed digital signal oscilloscope. In particular, a 2.5 Gbps data rate is successfully transmitted achieving receiver sensitivity of −50 dBm at 2 × 10−3 bit error rate (BER) for 32 quadrature amplitude modulation (QAM) with a system baud rate of 500 MHz. The wide bandwidth and high gain along with the excellent performance of the proposed 4 × 4 antenna array unit cell makes it an excellent candidate for future 5G wireless communication applications.

Progress Toward Accurate Measurement of Dielectric Barrier Discharge Plasma Actuator Power

The accurate measurement of power consumption by dielectric barrier discharge plasma actuators is a challenge due to the characteristics of the actuator current signal. Microdischarges generate high-amplitude, high-frequency current spike transients superimposed on a low-amplitude, low-frequency current. A high-speed digital oscilloscope was used to measure the actuator power consumption using the shunt resistor method and the monitor capacitor method. The measurements were performed simultaneously and compared to each other in a time-accurate manner. It was found that low signal-to-noise ratios of the oscilloscopes used, in combination with the high dynamic range of the current spikes, make the shunt resistor method inaccurate. An innovative, nonlinear signal compression circuit was applied to the actuator current signal and yielded excellent agreement between the two methods. The paper describes the issues and challenges associated with performing accurate power measurements. It provides insights into the two methods including new insight into the Lissajous curve of the monitor capacitor method. Extension to a broad range of parameters and further development of the compression hardware will be performed in future work.

Pulse shape discrimination using EJ-299-33 plastic scintillator coupled with a Silicon Photomultiplier array

Recent developments in organic plastic scintillators capable of pulse shape discrimination (PSD) have gained much interest. Novel photon detectors, such as Silicon Photomultipliers (SiPMs), offer numerous advantages and can be used as an alternative to conventional photo multiplier tubes (PMTs) in many applications. In this work, we evaluate the PSD performance of the EJ-299-33 plastic scintillator coupled with a SiPM array. 2D PSD plots as well as the Figure of Merit (FOM) parameters are presented to demonstrate the PSD capability of EJ-299-33 using a SiPM as the light sensor. The best FOM of 0.76 was observed with a 1.0MeVee (MeV-electron-equivalent) energy threshold, despite the high noise level of the SiPM array. A high-speed digital oscilloscope was used to acquire data, which was then processed offline in MATLAB. A performance comparison between two different PSD algorithms was carried out. The dependence of PSD quality on the sampling rate was also evaluated, stimulated by the interest to implement this setup for handheld applications where power consumption is crucial.

Energy harvesting based on acoustically oscillating liquid droplets

This paper presents a novel actuator for harvesting energy from ambient acoustic noise using acoustically oscillating droplets. When a liquid droplet sitting on a piezocantilever is excited by an acoustic wave around its natural frequency, its oscillation simultaneously bends the piezocantilever, which generates electric power owing to the piezoelectric effect. The oscillation amplitudes of water droplets with three different sizes (2, 4, and 6μl) hanging from a solid substrate were first investigated using high-speed images. The results showed that the droplet oscillation amplitude was strongly dependent on the applied frequency and was proportional to the droplet size. The maximum droplet oscillation amplitude occurred at the natural frequency of the droplets. Energy harvesting based on acoustically oscillating droplets was separately tested using a commercial piezocantilever. The oscillation behaviors of water droplets hanging from a flexible piezocantilever were also studied using high-speed images. The bending displacement and generated voltage of the piezocantilever by the acoustically oscillating water droplets were measured with a high-speed camera and digital oscilloscope, respectively, for different droplet sizes and distances between the droplet and piezoactuator. Both the bending displacement and generated voltage were strongly affected by the applied frequency and proportional to the droplet size but were inversely proportional to the distance. The force generated from the acoustically oscillating droplets was measured by using a load cell. The maximum force generated from the acoustically oscillating droplet (4μl) was about 123.9μN at the maximum bending displacement (about 1.5mm). The output voltage and power generated from the piezocantilever actuated by the acoustically oscillating droplets were measured with a custom-made electric circuit (mainly consisting of a voltage rectifier and load) for different droplet sizes. The maximum generated power for the load (10Ω) was measured to be about 80μW. As proof of concept, storage capacitor charging tests were conducted for 0.1 and 1μF capacitors using the acoustically oscillating droplets in three different sizes.

Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder) as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM). These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization–field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization) at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

Three-Dimensional VHF Lightning Mapping System for Winter Thunderstorms

Abstract A three-dimensional (3D) winter lightning mapping system employing very high frequency (VHF) broadband signals was developed for continuous remote observation in winter. VHF broadband pulses radiated by leader progression are received with three discone antennas arranged in a triangle (20–30 m) and recorded on a high-speed digital oscilloscope (1.25-GHz sampling) with GPS digital timing data. The two-dimensional (2D) mapping for azimuth and elevation of the VHF radiation sources was conducted by computing the arrival time differences of three pulses using a cross-correlation technique. From azimuth and elevation data from two sites extracted within a given time frame, 3D lightning mapping was performed using the triangulation scheme. An observation network for winter lightning was constructed within a comprehensive meteorological observation network in the Shonai area, which is located on the coast of the Japan Sea. This report includes the preliminary 2D and 3D mapping of winter lightning observed on 3 December 2010. The horizontal and vertical distributions of VHF radiation sources were consistent with the radar echo observed with X-band Doppler radar. These results indicate that the system can detect winter lightning discharges and perform 2D and 3D lightning mapping in detail.

Diffuse Coplanar Surface Barrier Discharge in Nitrogen: Microdischarges Statistical Behavior

We studied statistical behavior of microdischarges of diffuse coplanar surface barrier discharge (DCSBD) operated in nitrogen atmosphere at two input voltage regimes. We measured spectrally unresolved discharge patterns together with discharge electrical parameters using highspeed iCCD camera and digital storage oscilloscope. External synchronization enabled us to measure the discharge pattern during positive and/or negative half-period of input high voltage in the single-shotmode of operation. The comparison of microdischarges behavior during positive, negative and both half periods of input high voltage was performed for two levels of input voltage, i.e. voltage slightly above ignition voltage and high above ignition voltage (“overvoltage”). The number of microchannels crossing discharge gap was counted and compared with number of microdischarge current peaks observed during corresponding half-period of input high voltage. The relations of those incidences was shown and discussed.

Neutron-Gamma Pulse Shape Discrimination with a NE-213 Liquid Scintillator by Using Digital Signal Processing Combined with Similarity Method

Neutron-Gamma Pulse Shape Discrimination with a NE-213 Liquid Scintillator by Using Digital Signal Processing Combined with Similarity Method. Measurement of mixed neutron-gamma radiation is difficult because a neuclear detector is usually sensitive to both radiations. A new attempt of neutron-gamma pulse shape discrimination for a NE-213 liquid scintillator is presented by using digital signal processing combined with an off-line similarity method. The output pulse shapes are digitized with a high speed digital oscilloscope. The n-γ discrimination is done by calculating the index of each pulse shape, which is determined by the similarity method, and then fusing it with its corresponding pulse height. Preliminary results demonstrate good separation of neutron and gamma-ray signals from a NE-213 scintillator with a simple digital system. The results were better than those with a conventional rise time method. Figure of Merit is used to determine the quality of discrimination. The figure of merit of the discrimination using digital signal processing combined with of line similarity method are 1.9; 1.7; 1.1; 1.1; and 0.8 ; on the other hand by using conventional method the rise time are 0.9; 0.9; 0.9; 0.7; and 0.4 for the equivalent electron energy of 800 ; 278 ; 139 ; 69 ; and 30 keV.

Direct Fluorescent Decay Measurements Using High Speed Electronics

High speed data acquisition architecture is implemented as part of a time-resolved fluorescence detection instrument to directly measure the time course of fluorescent decay. The architecture is implemented using a very fast dynode chain photomultiplier tube and associated gating circuitry, a broad spectrum light emitting diode excitation source, very wide band electronics for amplification and filtering, and a high speed digital oscilloscope. The fluorescence decay of tris (2,2´-bipyridyl) ruthenium (II) is measured and the lifetime measurement is compared with that using other reported methods. The system’s architecture is thereby validated for data acquisition of broadband signals including transient fluorescent recording.

HLS bunch current measurement system

Bunch current is an important parameter for studying the injection fill-pattern in the storage ring and the instability threshold of the bunch, and the bunch current monitor also is an indispensable tool for the top-up injection. A bunch current measurement (BCM) system has been developed to meet the needs of the upgrade project of Hefei Light Source (HLS). This paper presents the layout of the BCM system. The system based on a high-speed digital oscilloscope can be used to measure the bunch current and synchronous phase shift. To obtain the absolute value of bunch-by-bunch current, the calibration coefficient is measured and analyzed. Error analysis shows that the RMS of bunch current is less than 0.01 mA when bunch current is about 5 mA, which can meet project requirement.

The most flexible system component: High speed digital oscilloscope

Oscilloscopes are often found in ATE systems as debug tools, but the high speed capture capabilities can expand their application into a multitude of anticipated and unanticipated testing needs. This extends the reader's understanding of the inherent measurement possibilities afforded by this important system component.

Identification of the controlling parameter for the set-state resistance of a TiO2 resistive switching cell

This study examined the parameter controlling the set-state resistance (Rset) of a Pt/TiO2/Pt resistive switching (RS) cell in unipolar RS mode. Although the compliance current in the current-voltage sweep had some effect on the Rset, the uncontrolled flow of charge from the parametric analyzer prevented making an accurate estimation of the parameters. The current transient in pulse switching observed using a high-speed digital oscilloscope and physical modeling showed that the capacitive charge moves vigorously at the moment of on-switching, and Rset is governed by the level of migrating charge. The actual switching time was ⪡50 ns.

Experimental and Simulation Studies of New Configuration of Virtual Cathode Oscillator

A new configuration of a virtual cathode oscillator (VCO) has been studied for high-power microwave generation. In this VCO configuration, a resonant cavity is used to enhance the beam-field interaction in order to improve the microwave efficiency. Experiments were carried out on a repetitive pulsed power generator "ETIGO-IV" (400 kV, 13 kA, 120 ns, 1 Hz). The output microwaves are diagnosed for peak power and dominant mode by using horn antennas and E-field probes. The microwave frequency is obtained by fast-Fourier transformation of the signal recorded by a high-speed digital oscilloscope. The initial experimental results obtained by E-field probes have indicated a beam-to-microwave conversion efficiency of /spl sim/10%. In addition, three-dimensional particle-in-cell simulations were carried out by using simulation code "MAGIC". Simulation results are compared with experimental results to examine the effect of the cavity and possible ways of further improvement of microwave efficiency.