Charge Measurements Research Articles

An integrated flux-symmetric spectrometer-magnet system for the SND@LHC experiment upgrade

The proposed upgrade of the SND@LHC experiment for the High Luminosity phase of the LHC (HL-LHC) will strongly benefit from the presence of a magnetized region, allowing for muon momentum and charge measurement. In this paper we describe an iron core magnet system that is partly integrated with the calorimeter and that is designed to respect the strict constraints from the available space in the experimental cavern, power consumption, and field requirements. Semi-analytical tools are introduced to explore the parameter space, in order to define the primary design options. A full 3-D analysis is then performed in order to validate the optimal choice, and to propose a conceptual design, including sizing of the components, detector performances and stray fields. Several technical options are also discussed, anticipating the design phase.

Spatiotemporal Measurement of Charge at Ceramic Substrate–Silicone Gel Interface in Medium-Voltage Power Modules

Spatiotemporal Measurement of Charge at Ceramic Substrate–Silicone Gel Interface in Medium-Voltage Power Modules

Techniques for surface charge measurements and exploring contact electrification

Techniques for surface charge measurements and exploring contact electrification

Accurate, Fast, and Non-Destructive Net Charge Measurement of Levitated Nanoresonators Based on Maxwell Speed Distribution Law

Nanoscale resonant devices based on optical tweezers are widely used in the field of precision sensing. In the process of driving the nanoresonator based on the Coulomb force, the real-time, precise regulation of the charge carried by the charged resonator is essential for continuous manipulation. However, the accuracy of the existing charge measurement methods for levitated particles is low, and these methods cannot meet the needs of precision sensing. In this study, a novel net charge measurement protocol for levitated particles based on spatial speed statistics is proposed. High-precision mass measurement based on Maxwell’s rate distribution law is the basis for improving the accuracy of charge measurement, and accurate measurement of net charge can be achieved by periodic electric field driving. The error of net charge measurement is less than 7.3% when the pressure is above 0.1 mbar, while it can be less than 0.76% at 10 mbar. This proposed method features real-time, high-precision, non-destructive, and in situ measurement of the net charge of particles in the medium vacuum, which provides new solutions for practical problems in the fields of high-precision sensing and nano-metrology based on levitated photodynamics.

Quantification of uncertainties in reference and relative dose measurements, dose calculations, and patient setup in modern external beam radiotherapy.

Uncertainties in the steps of external beam radiotherapy (EBRT) affect patient outcomes. However, few studies have investigated major contributors to these uncertainties. This study investigated factors contributing to reducing uncertainty in delivering a dose to a target volume. The EBRT process was classified into four steps: reference dosimetry, relative dosimetry [percentage depth doses (PDDs) and off-center ratios (OCRs)], dose calculations (PDDs and OCRs in a virtual water phantom), and patient setup using an image-guided radiation therapy system. We evaluated the uncertainties for these steps in conventionally fractionated EBRT for intracranial disease using 4-, 6-, and 10-MV flattened photon beams generated from clinical linear accelerators following the Guide to the Expression of Uncertainty in Measurement and an uncertainty evaluation method with uncorrected deflection. The following were the major contributors to these uncertainties: beam quality conversion factors for reference dosimetry; charge measurements, chamber depth, source-to-surface distance, water evaporation, and field size for relative dosimetry; dose calculation accuracy for the dose calculations; image registration, radiation-imaging isocenter coincidence, variation in radiation isocenter due to gantry and couch rotation, and intrafractional motion for the patient setup. Among the four steps, the relative dosimetry and dose calculation (namely, both penumbral OCRs) steps involved an uncertainty of more than 5% with a coverage factor of 1. In the EBRT process evaluated herein, the uncertainties in the relative dosimetry and dose calculations must be reduced.

Precision measurement of the topological charge of a fractional vortex beam based on angular-grating-diffraction OAM spectrum

Precision measurement of the topological charge of a fractional vortex beam based on angular-grating-diffraction OAM spectrum

Numerical investigation of electric charge measurement by PWP method at solid and liquid interfaces

When a liquid contacts a solid, physicochemical reactions form an electrical double layer (EDL) at the interface. Understanding the EDL is crucial to prevent electrical device failures, but few experimental methods can access this charge distribution. Recently, the pressure wave propagation (PWP) method has been explored. This paper presents simulations of current generated by a pressure wave through the EDL using the finite difference time domain (FDTD) method. A parametric study investigates the effects of EDL parameters and stimulus properties on the signal. Simulations with EDL data obtained experimentally for both conductive and dielectric liquids are carried out.

Evolution laws of charge mobility of transformer oil and pressboard material with temperature and electric field strength

Abstract Charge mobility, a pivotal parameter in the space charge analysis model for oil-pressboard insulation of converter transformer under DC electric fields, predominantly relies on theoretical or empirical data. The prevalent omission of empirical, measurement-based evaluations, combined with the neglect of temperature and electric field intensity effects, introduces uncertainties in the calculation of electric field and charge dynamics. Grounded on the principles of the electroacoustic pulse technique for space charge measurements, our investigation established a temperature-controlled platform to determine the charge-charge mobility in oil and pressboard insulation mediums. Utilizing diverse oil-pressboard insulation systems, this study identified the temporal patterns of both positive and negative charge mobilities and unravelled the mechanisms modulated by temperature and electric field intensity: (1) with increasing temperatures (from 20 °C to 80 °C) and intensifying electric field strengths (from 5kV mm−1 to 25kV mm−1), the charge mobility within transformer oil and pressboard exhibits a rising trend. Notably, temperature variations exert the most significant influence, yielding amplifications up to 24.8 times. (2) The intrinsic properties of different transformer oils and oil-impregnated pressboards result in pronounced differences in their charge transport behaviors. Specifically, naphthenic-based oil demonstrates enhanced charge mobility relative to its paraffin-based counterpart. In contrast, transformer oils with higher kinematic viscosities exhibit diminished charge mobility compared to those with lower viscosities. (3) A linear relationship is observed between the oil absorption rate and electrical conductivity, aligning closely with the insulating pressboard’s charge mobility. The evaluation of electric field and interface charge dynamics in oil-pressboard insulation under both DC and polarity-reversed conditions revealed that the electric field decay in naphthenic-based oil is more rapid than in paraffin-based oils. Moreover, both the magnitude and rate of interface charge accumulation in naphthenic-based oils exceed those in paraffin-based variants, further validating the accuracy of our charge mobility measurements and ensuing analysis.

Improved design of optical-microforce sensor with high thermal-mechanical stability for insulation charge ellipsometer testing application

Optical-microforce sensor is the core of the sensing module for the insulation charge ellipsometer testing, whose thermal-mechanical stability directly affects the charge measurement reliability. In this paper, based on molecular simulation, the improved design for SU-8 photoresist-based optical-microforce sensor is proposed. It is found that carboxyl-functionalized carbon nanotube/SU-8 photoresist composite system with 75 % cross-linking index possesses the comparatively better thermal-mechanical stability. Then, based on the photolithography process, modified and unmodified optical-microforce sensors are prepared. Meanwhile, the thermal-mechanical stability is evaluated from the experimental perspective. The experiment is consistent with the molecular simulation, showing that compared with the unmodified optical-microforce sensor with measurement fluctuation of 17.6 %, the modified sensor exhibits better thermal-mechanical stability, whose measurement fluctuation is only 5.3 % during the temperature range of 25–100 °C. Further, the optical-microforce sensor measurement performance evaluation platform is built. It is shown that the modified sensor could achieve the response to different frequency, different magnitude elastic wave and picosecond pulse width elastic wave, which could be applied in the insulation charge ellipsometer testing application.

TCellR2Vec: efficient feature selection for TCR sequences for cancer classification.

Cancer remains one of the leading causes of death globally. New immunotherapies that harness the patient's immune system to fight cancer show promise, but their development requires analyzing the diversity of immune cells called T-cells. T-cells have receptors that recognize and bind to cancer cells. Sequencing these T-cell receptors allows to provide insights into their immune response, but extracting useful information is challenging. In this study, we propose a new computational method, TCellR2Vec, to select key features from T-cell receptor sequences for classifying different cancer types. We extracted features like amino acid composition, charge, and diversity measures and combined them with other sequence embedding techniques. For our experiments, we used a dataset of over 50,000 T-cell receptor sequences from five cancer types, which showed that TCellR2Vec improved classification accuracy and efficiency over baseline methods. These results demonstrate TCellR2Vec's ability to capture informative aspects of complex T-cell receptor sequences. By improving computational analysis of the immune response, TCellR2Vec could aid the development of personalized immunotherapies tailored to each patient's T-cells. This has important implications for creating more effective cancer treatments based on the individual's immune system.

Composition Variation of the 2023 May 16 Solar Energetic Particle Event Observed by SolO and PSP

In this study, we employ the combined charged particle measurements from Integrated Science Investigation of the Sun on board the Parker Solar Probe (PSP) and Energetic Particle Detector on board the Solar Orbiter (SolO) to study the composition variation of the solar energetic particle (SEP) event occurring on 2023 May 16. During the event, SolO and PSP were located at a similar radial distance of ∼0.7 au and were separated by ∼60° in longitude. The footpoints of both PSP and SolO were west of the flare region, but the former was much closer (18° versus 80°). Such a distribution of observers is ideal for studying the longitudinal dependence of the ion composition with the minimum transport effects of particles along the radial direction. We focus on H, He, O, and Fe measured by both spacecraft in sunward and antisunward directions. Their spectra are in a double power-law shape, which is fitted best by the Band function. Notably, the event was Fe rich at PSP, where the mean Fe/O ratio at energies of 0.1–10 Mev nuc−1 was 0.48, higher than the average Fe/O ratio in previous large SEP events. In contrast, the mean Fe/O ratio at SolO over the same energy range was considerably lower at 0.08. The Fe/O ratio between 0.5 and 10 MeV nuc−1 at both spacecraft is nearly constant. Although the He/H ratio shows energy dependence, decreasing with increasing energy, the He/H ratio at PSP is still about twice as high as that at SolO. Such a strong longitudinal dependence of element abundances and the Fe-rich component in the PSP data could be attributed to the direct flare contribution. Moreover, the temporal profiles indicate that differences in the Fe/O and He/H ratios between PSP and SolO persisted throughout the entire event rather than only at the start.

Technical Committees: Recent Activities of the DEIS Technical Committee on “HVDC Cable Systems”: Two New Study Groups for Novel IEEE Standards on Space Charge Measurement

Technical Committees: Recent Activities of the DEIS Technical Committee on “HVDC Cable Systems”: Two New Study Groups for Novel IEEE Standards on Space Charge Measurement

Electrostatic attraction and charge accumulation of poultry red mites (Dermanyssus gallinae) under high electric fields

This study investigated the electrostatic properties and behavior of poultry red mites (Dermanyssus gallinae) under high-voltage electric fields. We evaluated mite mortality rates under various electrode gap distances and mite densities, quantified mite attraction to electrodes under different electric field strengths, and measured electrostatic charge accumulation on mites. The results showed that narrower electrode gaps and lower mite densities led to higher mortality rates. Mite attraction to electrodes increased significantly with the electric field strength, with over 85% of mites attaching to electrodes at field strengths ≥10 kV cm−1. The voltage rise time was found to negatively correlate with the mite attraction efficiency. Charge measurements revealed that mites accumulate electrostatic charge proportional to their number, with engorged mites exhibiting higher charges than their starved counterparts. These findings provide valuable insights into the electrical properties of D. gallinae and their response to electric fields, contributing to our understanding of mite behavior under electrostatic stimuli.

Evidence of Different Charging Behavior of Conductive and Dielectric Materials in Low-Temperature Plasmas and a New Diagnostic for Low-Energy Electron Absorption.

In any physical system where a surface is hit by electrons, the sticking probability s of the electrons is a central parameter governing, for example, the charging of the surface. For dielectrics, it could previously only be measured for high energies (>100 eV), while it is well-known for metals even at energies of only a few eV. Recent theoretical investigations concerning dielectrics such as silica predict values for s significantly below 1. With precision charge measurements on microparticles in the sheath of a low-pressure plasma, a difference in charge between silica and gold-coated particles is found, challenging the long-standing assumption in dusty plasma physics that dielectric and metallic particles charge in the same way for the first time. Based on the measured charging difference, the low-energy sticking coefficient of silica is obtained, validating the theoretical predictions and offering a new diagnostic for the otherwise quasi-inaccessible low-energy electron sticking of dielectric materials.

Adsorption behavior of in-house developed CO2-philic anionic surfactants

Incorporating CO2-philic functionalities into surfactant structure is proposed to address the drawbacks of conventional foaming agents such as premature rupture of lamellae in contact with oil, surfactant loss due to adsorption on rock or partitioning between oil and water, and salinity and temperature tolerance issues. Increased activity at the gas/water interface and less surfactant adsorption to the rock due to the presence of CO2-philic chains results in higher foam durability in the presence of oil. In the present paper, a comprehensive study on the adsorption of anionic CO2-philic surfactants onto sandstone rock surface is performed to understand adsorption mechanisms through the addition of CO2-philic tail groups in surfactant structure by observing the changes in concentration, static adsorption, and point of zero charge measurements. The static adsorption tests, Fourier Transform Infrared, and the X-ray Photoelectron Spectroscopy techniques were employed to investigate the interaction of surfactants with crushed Berea sandstone core sample at 90 °C. The static adsorption values of the S (single-tail), D (double-tail), and T (triple-tail) anionic surfactants were reported to be 0.53, 0.40, and 0.6 mg /g, respectively. The effect of alkali on the adsorption process of surfactants was also investigated and the adsorption of synthesized surfactants was found significantly low in alkaline conditions. A variety of analyses, including model fitting along with kinetics and thermodynamics studies at 30, 40, and 50 °C were performed to predict the adsorption behavior. The adsorption isotherm was found to best fit in Langmuir model. The process showed the best fit in the pseudo-second-order reaction kinetics model. The spontaneity of the adsorption process was verified by thermodynamic feasibility studies of the process.

Chemical interference between graphene oxide and polycarboxylate superplasticizer, and the resulting impact on the concrete strength, workability, and microstructure

Graphene oxide (GO) nanoreinforcement is shown to significantly improve the strength and durability of concrete at the expense of mix workability. While polycarboxylate superplasticizers (PCSP) addition has improved GO-cement/mortar strength and workability in existing literature, this article examines if this improvement is translated to concrete with lower cement and water contents. PCSP and GO showed colloidal instability and particulate aggregation through surface charge measurements, presumably caused by divalent Ca 2 + ion interbridging between the GO and PCSP. This chemical interference results in a 26% reduction in 28-day compressive strength and a 20% decrease in the workability of PCSP-treated GO-concrete. Microstructural examination reveals significantly larger pores in PCSP+GO cement than in GO-cement or PCSP-only cement due to the chemical interference induced by PCSP-GO interactions in cement and concrete. Hence, PCSP and GO interactions must be further researched for practical use in concrete structures.

Scalable on-chip multiplexing of silicon single and double quantum dots

Owing to the maturity of complementary metal oxide semiconductor (CMOS) microelectronics, qubits realized with spins in silicon quantum dots (QDs) are considered among the most promising technologies for building scalable quantum computers. For this goal, ultra-low-power on-chip cryogenic CMOS (cryo-CMOS) electronics for control, read-out, and interfacing of the qubits is an important milestone. We report on-chip interfacing of tunable electron and hole QDs by a 64-channel cryo-CMOS multiplexer with less-than-detectable static power dissipation. We analyze charge noise and measure state-of-the-art addition energies and gate lever arm parameters in the QDs. We correlate low noise in QDs and sharp turn-on characteristics in cryogenic transistors, both fabricated with the same gate stack. Finally, we demonstrate that our hybrid quantum-CMOS technology provides a route to scalable interfacing of a large number of QD devices, enabling, for example, variability analysis and QD qubit geometry optimization, which are prerequisites for building large-scale silicon-based quantum computers.

Simulation and commissioning of a Faraday cup for absolute charge measurements of very high-energy electrons in-air at PEER

The Pulsed Energetic Electrons for Research (PEER) beamline at the ANSTO Australian Synchrotron comprises a 100 MeV linac injector that is currently being developed for ultra-high dose-rate, very high-energy electron radiotherapy research. Previously, dosimetry studies discovered a lack of reliable charge measurement to the in-air end station, though no change in response was recorded in fast current transformer measurements, the only available diagnostic device for measuring charge. This work describes the process of simulating and then commissioning a purpose-built Faraday cup to ascertain absolute in-air charge measurements at PEER. By combining simulation data with experimental results, the PEER Faraday cup is shown to possess a primary electron capture efficiency of (99.22 ± 0.10)%, with a net capture efficiency due to secondary electron emission of (97.87 ± 0.24)%. These results show the PEER Faraday cup performs as intended and, when scaled against simulations, will be suitable for measuring absolute charge at PEER.

Two-Dimensional Space Charge Measurement in Cable Joint Model Using the Pulsed Electroacoustic Method

Two-Dimensional Space Charge Measurement in Cable Joint Model Using the Pulsed Electroacoustic Method

Uncertainty of Electric Field Estimation in a Full-Sized Cable Based on Space Charge Measurement

Uncertainty of Electric Field Estimation in a Full-Sized Cable Based on Space Charge Measurement