Time Counter Research Articles

The latest performance and refurbishment of the pixelated Timing Counter (pTC) in the MEG II experiment

We have operated the MEG II pixelated timing counter maintaining its overall timing resolution at high level for precise timing measurement of positrons. Since its construction in 2017, the detector’s pixels have shown degradation with high-rate beam irradiation and components (plastic scintillators, SiPMs) aging over time. In 2024, using new 960 SiPMs, we produced and mounted new 80 pixels onto the detector with estimation of the performance improvement.

Test and characterization of SiPMs for the upgrade of MEGII high resolution Timing Counter

The MEG II experiment based at PSI (Zuerich, Switzerland) has been committed and is taking data since 2021 to improve sensitivity on the decay μ+ → e+ γ. The pixelated Timing Counter (pTC), consisting of two arrays of 512 5 mm thick scintillator pixel each, read out by 6 3×3 mm2, 50 μm cell, Silicon Photomultipliers (SiPMs) from AdvanSiD, for a total of 6144 SiPM, achieves an overall resolution in the positron impact time of ∼43 ps when exploiting multiple measurements. To additionally improve this resolution, 4×4 mm2, 40 μm cell SiPMs have been selected to substitute a fraction of the old ones (about 1000 of them overall). By means of an automated test system, a first group of them has been characterized (measuring their breakdown voltage and their I-V curves), to match as much as possible SiPMs with the same gains in each pixel, in order to maximize the pixel time resolution. Such automated test system will be presented, together with some preliminary results on single pixel time resolution and the expectations of the average time resolution of the pTC in the coming years.

Real-Time Walk Error Compensation Method Using Echo Signal Magnitude Measurement in ToF Laser Scanners.

The rapid advancement of mobile laser scanner technology used for terrain mapping, among other things, imposes increasing requirements for scanning frequency and distance measurement accuracy. To meet these requirements, rangefinder modules are expected to operate with high echo signal dynamics and to allow accurate distance measurement even based on single-laser-pulse echo detection. Such performance can be potentially achieved using pulsed time-of-flight (ToF) laser rangefinders (LRF). In conventional ToF modules, however, the STOP signal (for time counter interruption) is generated using a straightforward fixed-threshold comparator method. Unfortunately, it corresponds to the so-called walk error, i.e., the dependence of the measured time of flight on the magnitude of the echo signal. In most ranging applications, however, the LRF detection channel can be exposed to an extremely large span of received echo power levels, which depend on the distance measured, type of target surface, atmospheric transmission, etc. Thus, the walk error is an inseparable element of the conventional ToF technique and creates a fundamental limit for its precision. This article presents a novel method of walk error compensation in real time. By using our authorial electronic circuit for measuring the magnitude of the echo signal, it is possible to effectively compensate for the walk error even when the echo signal brings the detection channel amplifiers into saturation. In addition, the paper presents a laboratory method for calibrating the walk error compensation curve.

The Effect of Methane–Ammonia and Methane–Hydrogen Blends on Ignition and Light-Around in an Annular Combustor

Abstract The use of hydrogen and ammonia in gas turbines, either alone or blended with natural gas, poses various technical challenges for combustion systems, including ignition. Depending on the fuel composition, the laminar flame speed and the ratio of unburned to burned gas density (dilatation ratio) of hydrogen and ammonia flames can be well outside the range seen in natural gas flames. Previous studies in annular combustion chambers have provided evidence of the importance of these properties in determining the ignition dynamics including light-around times. So far, these studies have mostly considered hydrocarbon fuels, have been limited to only a few runs, and have not yet systematically investigated variations in the dilatation ratio and the flame speed but rather have considered them as a lumped parameter. To investigate these effects in more detail, experiments characterizing the light-around times were carried out on an atmospheric annular combustor in which the dilatation ratio and the laminar flame speed was independently varied. This was achieved by varying the equivalence ratio and employing a variety of different hydrocarbon fuels (ethylene, propane, and methane) and fuel blends of methane–ammonia and methane–hydrogen. Light-around times were evaluated from global chemiluminescence measurements obtained using an azimuthal array of photomultipliers placed round the combustor chamber as well as high speed imaging. To improve statistical certainty, more than 3000 ignition and light-around times were measured with 30 repetitions obtained for each operating condition. To provide some insight into the light-around dynamics in specific cases, 900 of the 3000 sets included high-speed OH* chemiluminescence images. Light-around times for premixed pure hydrocarbon flames showed a similar dependence on the laminar flame speed as reported in previous studies. For the range of ammonia fuel blends investigated, an increase in laminar flame speed leads to a predictable increase in the flame propagation speed, as in the case of hydrocarbon fuel. Furthermore, collapse of this dependence for all blends could be achieved when corrected for an effective Lewis number, noting that all Lewis numbers for these blends were above unity. However, for hydrogen fuel blends, a decrease in dilatation ratio was found to decrease the light-around time counter to existing experimental results on the ignition of hydrocarbon fuels for which we currently do not have an explanation.

The construction and characterization of MgO transmission dynodes

In this work we demonstrate that ultra-thin (5 and 15 nm) MgO transmission dynodes with sufficient high transmission electron yield (TEY) can be constructed. These transmission dynodes act as electron amplification stages in a novel vacuum electron multiplier: the Timed Photon Counter. The ultra-thin membranes with a diameter of 30 μm are arranged in a square 64-by-64-array. The TEY was determined with a scanning electron microscope using primary electrons with primary energies of 0.75–5 keV. The method allows a TEY map of the surface to be made while simultaneously imaging the surface. The TEY of individual membranes can be extracted from the TEY map. An averaged maximum TEY of 4.6±0.2 was achieved by using 1.35 keV primary electrons on a TiN/MgO bi-layer membrane with a layer thickness of 2 and 5 nm, respectively. The TiN/MgO membrane with a layer thickness of 2 and 15 nm, respectively, has a maximum TEY of 3.3±0.1 (2.35 keV). Furthermore, the effect of the electric field strength on transmission (secondary) electron emission was investigated by placing the emission surface of a transmission dynode in close proximity to a planar collector. By increasing the electric potential between the transmission dynode and the collector, from -50 V to -100 V, the averaged maximum TEY improved from 4.6±0.2 to 5.0±0.3 at a primary energy of 1.35 keV with an upper limit of 5.5 on one of the membranes.

FPGA-Based Time-to-Digital Converter for Pulsed Laser Ranging

This paper implements a Time-to-digital Converter (TDC) in a field-programmable gate array (FPGA), which is made for a single-photon-counting-based pulsed laser ranging system. The fine time is measured by the Tapped Delay Line (TDL) constructed in an internal dedicated carry chain of the FPGA. The length of the TDC is longer than one clock period, and the whole CARRY4 is utilized as a delay unit. The proposed TDC is made up of the fine time measurement module, encoder, coarse time counter, and data transport module, which are achieved in a resource-tensed FPGA Xilinx-ZYNQ. As this paper is done in a shared FPGA, the presented TDC can replace the ASIC-TDC GP22 as the TOF measurement module. By measuring the same time interval and modifying the fixed error in TDC, the results show that the time resolution can reach 53 ps. Compared with the ASIC-TDC GP22, both linearity and measurement range are improved in the proposed TDC, which makes the pulsed laser ranging system more flexible and integrated.

Operational Adaptation of Digital Filter Parameters when Changing the Discrete Time Step in the Problems of Forming the Control of Unmanned Vehicles Using Satellite Measurements

For the tasks of controlling unmanned vehicles using external information signals, in some cases, a change in the time parameters T0 of periodic data receipt is typical. Such systems, the processing of incoming information in order to form digital control is implemented by digital filters (DF), based on discrete samples x[k] of some continuous signal x(t) at quantization times tk=k*T0 Here T0[seconds]- the period of discreteness in time, k=0,1,2,.. an integer variable, essentially a time counter. The properties of the filter are uniquely specified by its specific mathematical model - the discrete impulse transient function [1,3] of the filter (DITF), which characterizes the filter operation at a specific step T0= 1/f0, where f0 (hertz) is the frequency. When the time intervals T0 of data arrival change, for example, due to a change in the transmission conditions in the radio channel, or due to a change in the location of the satellite constellation, the filter properties will change during operation [2], and if T0 changes significantly, such filtering can lead to unsatisfactory results. In this paper, for the parameters of the digital filter, the adaptation problem is posed and solved, which ensures the invariance of the nature DITF, in contrast to the stabilization of the frequency properties of the digital filter, studied in [4]. To rebuild the numerical parameters of the filter, an algorithm is proposed that uses information about the time intervals obtained by direct measurement. At the stage of filter development, a special recalculation matrix is formed and when the filter is running in real time, the digital filter parameters are recalculated. For a model example, the calculation results are presented, which show good tuning accuracy, stable filter characteristics, as well as the simplicity of the required calculations on board with a significant change in time intervals.

Cost-effective equipment for surface pre-treatment for cleaning and excitation of substrates in semiconductor technology

This article presents a cost-effective ultraviolet-ozone cleaner (UV/O3 Cleaner) for surface pre-treatment of substrates in the field of semiconductor technology. The cleaner consists of two chambers, the upper one contains the electronics, including the time counter. The lower chamber contains the two UV sterilisation lamps and a UV reflector of anodized aluminium, which confines the area of high Ozone concentration in the area of interest. The device is successfully used for surface cleaning and modification of different materials. To this end, the two important wavelengths 253.7 nm (excitation of organic residues) and 184.9 nm (production of ozone from the atmospheric environment as a strong oxidant) were first detected. The effectiveness of UV/O3 cleaning is demonstrated by improving the properties of indium tin oxide (ITO) for OLED fabrication. The contact angle of water to ITO could be reduced from 90° to 3° and for diiodomethane, it was reduced from 55° to 31° within the 10 min of irradiation. This greatly improved wettability for polar and non-polar liquids can increase the flexibility in further process control. In addition, an improvement in wettability is characterized by measuring the contact angles for titanium dioxide (TiO2) and polydimethylsiloxane (PDMS). The contact angle of water to TiO2 decreased from 70° to 10°, and that of diiodomethane to TiO2 from 54° to 31°. The wettability of PDMS was also greatly increased. Here, the contact angle of water was reduced from 109° to 24° and the contact angle to diiodomethane from 89° to 49°.Article HighlightsWe report a cost-effective dry-cleaning device for surface cleaning and modification based on ultraviolet-ozone irradiation.Contact angle measurements show an increase of wettability for different materials due to surface modification.The UVO3 pre-treatment improves layer formation and optoelectrical properties of OLEDs.

Operational results with the pixelated Time Detector of MEG II experiment during the first year of physics data taking

The MEG II experiment was designed to improve by an order of magnitude the sensitivity of 4.2×10−13 reached by MEG on the branching ratio of the μ+→e+γ decay. The resolution of the positron timing is improved by using a segmented pixelated Timing Counter (pTC) where each counter is read independently. The pTC was commissioned in several engineering runs as well as in the first year of physics run (2021) at the πE5 beam line at PSI. Degradation of time resolution performance is observed and a program of partial upgrading the pTC is ongoing.

The performances of undershot waterwheel with butterfly-shaped blades and the radius of grasshopper's elbow: The utilization efforts for river electrical energy potential

Based on the amount of discharge or current, the river flows in Central Kalimantan have the potential to produce electrical energy. The purposes of this study were to design an undershot type of floating waterwheel and to test the effective bending angle at the radius of the grasshopper elbow in producing the most optimum power. This research uses experimental methods. The tools used are: mobile phone, multimeter, the gate of light, timer counter, flow rate, and the dimensions of the waterwheel diameter is 6 meters. Grasshopper angles vary from 0°, 30°, 45°, 60o, and 90° with a submerged blade depth of 0.24 m. The results showed that the undershot waterwheel with a flexible pinwheel (like a grasshopper's elbow) produced a faster and more effective rotation than a wheel with a fixed pinwheel and blades. Because the waterwheel has a flexible pinwheel and the butterfly blades experience little resistance when moving in water, the wheel generates more electrical energy than a wheel with fixed pinwheels and blades.At the angle of bending of the radius of the grasshopper blade 30º with the butterfly blade, it produces more optimal electrical energy than angles 0°, 45°, 60o, and 90°. Suggestions for further research are to test the waterwheel in weak and medium current rivers

A symmetrized and simplified Bernoulli trial collision scheme in direct simulation Monte Carlo

Here, a symmetrized and simplified Bernoulli trials (SSBT) scheme based on the probabilistic approach is introduced to provide less-restricted conditions in choosing selected pairs. Unlike the simplified Bernoulli trials (SBT) method, the SSBT scheme picks the second particle of a selected pair from a whole list of particles with equal probability; it prevents repetitive collisions by introducing a procedure to avoid duplicate colliding pairs. The efficiency of this newly introduced algorithm is investigated in benchmark problems such as a collision frequency test case, Fourier heat transfer, dissociation of simple gas, and hypersonic cylinder flow. Compared with SBT, no time counter (NTC), and nearest neighbor (NN) collision algorithms, the results show that the SSBT method predicts the solutions quite accurately. In the collision frequency test case and Fourier test case, we show that the SSBT scheme could work with few particles per cell (one or even less) if an appropriate space and time discretization is employed. The symmetrized algorithm of the SSBT scheme improves the quality of the selection process, which leads to a smaller sample size in the highly non-equilibrium problem of hypersonic cylinder flow to achieve the same convergence limit at that of the SBT and NN schemes. In addition, the SSBT scheme has inherently a lower separation of free paths in the stagnation point of the cylinder test case compared to the SBT scheme for the same grid test case. These features make SSBT a new, robust model that could be presented as an alternative to state-of-the-art models.

Fabrication of Digital Harmonic Vibration Practicum Using Phototransistor Sensor with Arduino-Uno Microcontroller

The problem in the harmonic vibration practicum is in calculating time accurately. Commonly, the time counter used was a stopwatch, but it was unable to provide valid data. As a result, the student has difficulty seeing the relationship between concepts with practical results in the laboratory. To overcome these problems, in this study, we developed a harmonic vibration practicum tool that is equipped with a digital timer using an Arduino Uno microcontroller as a light sensor. An Arduino can be programmed via a PC according to the wishes of the developer. This study was development research using a 4-D model (Define-design-develop-dissemination). The define and design stages respectively to find problems in the harmonic vibration practicum tool. The tool is finally designed and then calibrated, validated, and practical. The calibration results show that the percentage difference for repetition measurement and comparison that values with theory was 0.008% and 3.98%, respectively. In addition, the validation results show an average percentage of 87% or very valid. For practicality, the result through a limited test of Physics students of IAIN Batusangkar in the second semester shows a very practical response with a percentage of 85.96%. Due to time constraints, the dissemination stages have not been carried out in this study.

Design and Implementation of High Precision Synchronization Controller for Gated Imaging

In this paper, we have designed a high-precision synchronization controller for gated imaging. The design scheme is proposed according to the semiconductor laser arrays overall range-gated imaging system composition and working principle. The programming of control logic is illustrated in detail from the main time counter, mode control logic, key control decoder, pulse generator, automatic frequency generator and display control. Finally, a synchronization controller with precision of 80 ns and frequency of 12 khz was developed. The whole system joint debugging test shows that the indicators of the synchronization controller have reached the expected goal, and have met the current technical requirements of gated imaging within 3 km in the atmospheric environment.

Development of a New Hybrid Stochastic/Trajectory Droplet Collision Model for Spray Simulations in Internal Combustion Engines

Focusing on the spray simulation in engines using the Lagrangian-Drop Eulerian-Fluid (LDEF) approach, a new hybrid stochastic/trajectory (HST) droplet collision model with the improved collision frequency, the redivided collision cell, and an updated method for selection of the candidate collision pairs was developed in this study. The stochastic method used in the HST model was based on the theoretical framework of the time-counter (TC) direct simulation Monte Carlo (DSMC) method. Besides the stochastic method, the trajectory method was also introduced for the cases with sparse spray conditions in order to improve the reliability of the model predictions. The factor of “every parcel represents a certain number of droplets” was well considered in the calculations of the droplet collision frequency in the present model, which has not been attracted enough attention in previous models. Moreover, an adaptive collision cell technique was used for reducing the dependence of the calculation results on the computational mesh. The formula for selecting the collision pairs was updated in order to accurately reproduce the spatial distribution of the spray droplets after collision. To assess the performance of the droplet collision model, the experimental data with the direct spray-to-spray impingement under wide operating conditions were used for model validations. In addition, the numerical results by the droplet collision models including O'Rourke model, Nordin model, and no-time-counter (NTC) model were presented for comparison. The results indicate that the HST model is capable of satisfactorily reproducing the spray morphology, collision frequency, and Sauter mean diameter (SMD) of the droplets during the spray process. Meanwhile, good independence on the computational grid size, time step, and parcel number can be achieved by the HST model.

Single-photon ranging with hundred-micron accuracy

Single-photon detectors based on avalanche photodiodes and time-correlated single-photon counting technology are widely used in pulsed laser ranging. The ranging accuracy is one of the most important performances of laser ranging. In this work, a laser ranging method based on high-precision single-photon detector is developed to achieve laser ranging for non-cooperative targets with hundred-micron-level ranging accuracy. In the system, a low-time jitter Si APD single photon detector, picosecond pulsed laser and high-precision timing counter are used to reduce the time jitter of the ranging system, and a reference position is added to suppress the influence of delay drift of the system. And a laser interferometer system with a ranging resolution of 1 nm and an accuracy of 0.5 ppm is used to calibrate the distance of each movement of the ranging target. The photon flight time accuracy of 0.5 ps is achieved while the integral time ≥ 3 s. The ranging accuracy of 65 μm@RMS is realized, while the target is 2 m away. This work is one of the highest levels of pulsed time-of-flight ranging, and provides an effective technology for high-precision ranging and imaging of long-range non-cooperative targets.

Evaluation of the generalized bernoulli trial-transient adaptive subcell (GBT-TAS) collision scheme in treating rarefied gas flows

Collision process, the most complicated evolution term in the Boltzmann or Kac stochastic equations, is treated statistically in the direct simulation Monte Carlo (DSMC) method. The treatment of collision pair selection is of crucial importance in DSMC. A subsequent of several collision algorithms called Bernoulli-trials family schemes have been put forward, which were mathematically based on the Kac stochastic equation. The purpose of this paper is to report an extensive evaluation of the most recent variant of the Bernoulli Trials schemes, i.e., Generalized Bernoulli-trial (GBT) in treating standard problems such as cavity flow and hypersonic flow around a cylinder. The key feature of the GBT collision algorithm is its adaption to any number of particle pairs (Nsel) and its lower computational costs compared to standard schemes. The results show that the GBT scheme, compared to the standard “No Time Counter (NTC)”, “Nearest neighbor (NN)” and “Simplified Bernoulli Trials (SBT)” schemes, successfully captures the collision frequency in the cavity flow, shock wave and wake structure in the cylinder flow and held the same level of accuracy as the other standard collision schemes using a wide range of desired Nsel. A comparison of two variants of the GBT scheme (Scheme 1 and Scheme 2) indicates that Scheme-1 performs the simulation with a lower computational cost. The results prove that using a variable particle per subcell (PPSC) control approach significantly improves the collision probability accuracy and performance of the GBT scheme, especially in regions with high requirements for accurate collision process calculation.

Measurement of the transmission secondary electron yield of nanometer-thick films in a prototype Timed Photon Counter

We measure the transmission secondary electron yield of nanometer-thick Al2O3/TiN/Al2O3 films using a prototype version of a Timed Photon Counter (TiPC) . We discuss the method to measure the yield extensively. The yield is then measured as a function of landing energy between 1.2 and 1.8 keV and found to be in the range of 0.1 (1.2 keV) to 0.9 (1.8 keV). These results are in agreement to data obtained by a different, independent method. We therefore conclude that the prototype TiPC is able to characterise the thin films in terms of transmission secondary electron yield. Additionally, observed features which are unrelated to the yield determination are interpreted.

Design of a Switching Flyback Transformer as High Voltage and Frequency Power Supply for Raw Milk Cold Plasma Sterilization

Plasma is one of the four fundamentals states of matter other than solid, liquid and gas. In terms of temperature, plasma can be classified into Hot Plasma occurs in thermal equilibrium, Thermal Plasma occurs in non-thermal equilibrium, Cold Plasma occurs in non-thermal equilibrium Cold plasma is an ultra-fast method of sterilization that operates under ambient temperatures (ideal for thermolabile products) at a low running cost and is environment-friendly. Therefore, technology is needed to solve the problem through the innovation of a milk sterilization machine with the principle of non-thermal plasma sterilization by utilizing plasma technology to reduce microbial contamination. The output frequency and voltage are determined through software simulation using voltmeter, oscilloscope, and counter timer. After 220VAC supplies a voltage step down and rectifier circuit to produce a 12VDC output voltage to supply the Switching circuit voltage and the Flyback Transformer driver. Rated voltage and frequency reach 20kV 15kHz.The positive wire from the Flyback Transformer is connected to the acrylic box filled with water (positive electrode) and the ground wire is connected to another acrylic sheet (ground electrode. The milk medium to be sterilized can be placed on the positive electrode or between the ground and positive electrodes. Non-thermal plasma has an effective ability to decontaminate bacteria. This is because plasma is composed of a mixture of ionized particles, reactive radical molecules, and also ultraviolet Schematic circuit design has been successfully simulated. Acrylic sterilization media designs can be used to generate plasma. The mechanism of bacterial sterilization in milk is by the activity of inhibiting bacterial biofilms which can lead to bacterial DNA damage through reactive species in the non-thermal plasma used. Milk quality testing is carried out based on comparison of supporting literature with milk quality requirements according to SNI 3950: 2014.

A Hundred Acres of America: The Geography of Jewish American Literary History

A Hundred Acres of America: The Geography of Jewish American Literary History

Analysis Of Queuing Models Of Fast Food Restaurant with Simulation Approach

Queues in the cashier area in food purchases is one of the problems that often occurs in business processes in the community. Queues occur because of an imbalance between those served and their services. In fast food restaurants like XYZ, queues generally occur during lunch breaks or at dinner time. The purpose of this study is to determine the queuing model that occurs in the XYZ cashier area and analyze whether the queuing model is appropriate and efficient by comparing the previous model with the simulation results that have been carried out with the help of Anylogic software. The restaurant queue system is 3 queue lines and 3 counters. The average length of service and the interval of arrival of workers is 125.1 seconds and 67.5 seconds. Preliminary observational data show the average service time counters 1, 2 and 3 are 111, 136, 138 seconds. This fact shows that there is a long queue, the number of customers served at relatively low time units and work imbalances between operators. The results of the best queue simulation are proven to have shorter queues and the highest number of customers served per unit time. Based on the simulation results obtained by replacing 3 queue lines into 1 queue line and increasing the number of customers served is 74 people from 129 customers with the percentage of customers at each counter that is 28.38% for counter 1, 27.03% for counters 2 and 44, 59% for counter 3.