Incident Position Research Articles

Study of single event effect for the InP-based HEMT with In0.53Ga0.47As/In0.3Ga0.7As/In0.7Ga0.3As composite channel

In this study, the single event effects in In0.53Ga0.47As/In0.3Ga0.7As/In0.7Ga0.3As composite channel InP-based HEMT are investigated using TCAD simulation for the first time. Due to the higher conduction band difference between bottom In0.7Ga0.3As channel and InAlAs buffer, the electrons in the buffer layer induced by ions strike cannot enter the channel, led to reduce the peak concentration in the composite channel and significantly weakened the drain current for composite channel device. Meanwhile, higher barrier height under the gate for composite channel InP-based HEMT is formed after particle strike, and further attenuate the drain current. Therefore, the single event effects can be effectively reduced by designing channel structure. In addition, drain voltage and incident position also show significant impact drain current. With the increase in the drain voltage, the drain current increase and the most sensitive incident position is the gate electrode for the device.

Light-driven mixing strategy inside a nanofluid droplet by asymmetrical Marangoni flow

PurposeThe purpose of this study is to establish an effective numerical simulation method to describe the flow pattern and optimize the strategy of noncontact mixing induced by alternating Gaussian light inside a nanofluid droplet and analyzing the influencing factors and flow mechanism of fluid mixing inside a droplet.Design/methodology/approachFirst, the heat converted by the alternating incident Gaussian light acting on the nanoparticles was considered as the bulk heat source distribution, and the equilibrium equation between the surface tension and the viscous force at the upper boundary force was established; then, the numerical simulation methods for multiple-physical-field coupling was established, and the mixing index was used to quantify the mixing degree inside a droplet. The effects of the incident position of alternating Gaussian light and the height of the droplet on the mixing characteristics inside a droplet were studied. Finally, the nondimensional Marangoni number was used to reveal the flow mechanism of the internal mixing of the droplet.FindingsNoncontact alternating Gaussian light can induce asymmetric vortex motion inside a nanofluid droplet. The incident position of alternating Gaussian light is a significant factor affecting the mixing degree in the droplet. In addition, the heat transfer caused by the surface tension gradient promotes the convection effect, which significantly enhances the mixing of the fluid in the droplet.Originality/valueThis study demonstrates the possibility of the chaotic mixing phenomenon induced by noncontact Gaussian light that occurs within a tiny droplet and provides a feasible method to achieve efficient mixing inside droplets at the microscale.

Experimental Characterization of High Tolerance to Beam Irradiation Conditions of Light Beam Power Receiving Module for Optical Wireless Power Transmission Equipped with a Fly-Eye Lens System

This paper is an experimental characterization of a light-receiving module containing a fly-eye lens system with high tolerance to beam irradiation conditions. The fly-eye lens system, which is tolerant to fluctuations in beam shape, beam size, number of beams, beam incident position, and beam incident direction, was proposed, a light receiver module with a fly-eye lens system was constructed, and its characteristics were evaluated. The effect of the beam size on the fly-eye lens system was evaluated and the tolerance to misalignment of beam incident position was measured. When a GaAs solar cell was irradiated with a laser beam of 450 nm wavelength and 6 W light output through a 90 cm long water tank with tap water, a maximum output of 0.755 W was obtained as underwater OWPT. In addition, a fly-eye lens system with mirrors applied to four surfaces was proposed and fabricated as a light-receiving side module that can receive high incident angles from any direction of up, down, left, and right and its effectiveness was clarified through experiments.

Comprehensive study of the radiation effects on the LDMOS transistors

The reliability of power devices is attracting more and more attention, especially in the extreme radiation environment. The laterally diffused metal–oxide–semiconductor (LDMOS) has been widely used in high voltage integrated circuits. In this paper, the radiation effects of LDMOS transistors are extensively investigated through three-dimensional (3D) TCAD simulations, including Total-Ionizing Dose (TID), Single-Event Effect (SEE) and Transient Dose Rate Effect (TDRE). Firstly, the mechanism of TID effect on the LDMOS is revealed in consideration of temperature variations. Secondly, the single-event effect of the LDMOS is studied with different incident positions, linear energy transfer (LET) values, incident lengths, incident angles, bias conditions and temperatures. Besides, the combined effect of total-ionizing dose and single-event burnout is characterized. Finally, transient response of the LDMOS under transient γ radiation is also studied comprehensively. Therefore, it gives an insight into the physical mechanisms and response characteristics of complex radiation effects, which can provide guidance for radiation-hardened by design and application of the LDMOS devices.

Oropharyngeal cancer: a clinical case report

Introduction: The National Cancer Institute (INCA) estimates that for each year of the triennium 2020/2022, 15,190 new cases of cancer in the mouth and oropharynx are diagnosed in Brazil. In the global context, oropharyngeal cancer (OPC) is in the sixth position of cancer incidence. The most frequent form, about 90%, is squamous cell carcinomas. Objective: It was to present a clinical case report of oropharyngeal cancer in an octogenarian patient, to present the main diagnostic and treatment procedures in advanced age. Methods: The present study was elaborated according to the rules of the CARE case report. Scientific search engines: PubMed, Embase, Scopus, Google Scholar, Scientific Electronic Library Online (Scielo), published in Portuguese in the last 10 years. Case report and Conclusion: Based on the objective of this study and the literary findings, it showed that knowledge about OPC is essential for dental professionals, which plays a fundamental role in the diagnosis of oral cancers, requiring incisional biopsy. From the case described, it became evident the need for a partnership with a licensed psychologist, for the psychological preparation of the patient who will receive the news of the positive result for oropharyngeal cancer and the follow-up of the same throughout the treatment.

2D Thermal Maps Using Hyperspectral Scanning of Single Upconverting Microcrystals: Experimental Artifacts and Image Processing

Whereas lanthanide-based upconverting particles are promising candidates for several micro- and nanothermometry applications, understanding spatially varying effects related to their internal dynamics and interactions with the environment near the surface remains challenging. To separate the bulk from the surface response, this work proposes and performs hyperspectral sample-scanning experiments to obtain spatially resolved thermometric measurements on single microparticles of NaYF4: Yb3+,Er3+. Our results showed that the particle's thermometric response depends on the excitation laser incidence position, which may directly affect the temperature readout. Furthermore, it was noticed that even minor temperature changes (<1 K) caused by room temperature variations at the spectrometer CCD sensor used to record the luminescence signal may significantly modify the measurements. This work also provides some suggestions for building 2D thermal maps that shall be helpful for understanding surface-related effects in micro- and nanothermometers using hyperspectral techniques. Therefore, the results presented herein may impact applications of lanthanide-based nanothermometers, as in the understanding of energy-transfer processes inside systems such as nanoelectronic devices or living cells.

Controllable Peculiar Spin‐Dependent Transverse and In‐Plane Shifts of Airy Beam

AbstractGenerally, most of the photonic spin Hall effect (SHE) are investigated based on the Gaussian beam, and the research of the photonic SHE in novel beams with non‐Gaussian distribution is relatively rare. The Airy beam is one of the novel beams whose initial field distribution is asymmetric and tunable. Thus, it is necessary to explore the photonic SHE in the Airy beam. Here analytical solutions for the transverse and in‐plane shifts of the Airy beam are derived, and the peculiar photonic SHE of the Airy beam is systematically researched. The theoretical research results show that the transverse shifts of the left‐ and right‐handed circularly polarized beams are asymmetric, and the in‐plane shifts of the left‐ and right‐handed circularly beams are identical. More importantly, the variation rules of the transverse and in‐plane shifts with the incident centroid position are obtained, and the incident centroid position is regulated by the decay factor of the Airy beam. That is, the spin‐dependent transverse and in‐plane shift can be manipulated flexibly and purposefully by adjusting the beam parameter. It is believed these findings will provide more ideas for exploring the application of the photonic SHE based on novel beams.

First demonstration of a novel single-end readout type position-sensitive optical fiber radiation sensor based on wavelength-resolved photon counting

In this study, a single-end readout type position-sensitive optical fiber radiation sensor was developed. Using the wavelength dependency of light attenuation inside the optical fiber, the incident position of radiation at the fiber can be estimated reversely. Instead of a spectrometer, we employed bandpass filters and photon-counting head as a photodetector to improve detection efficiency. The detection efficiency of a 10 m long plastic scintillation fiber at the 5 m position from the readout end was evaluated to be in the range of 0.08–0.12 % for 662 keV gamma-rays from 137Cs and 2.6–3.9 % for beta-rays from 90Sr/90Y when a bandpass filter transmitting photons with a wavelength of 500 nm was used. A basic measurement test of radiation intensity distribution was conducted using a 90Sr/90Y radioactive point source. A field test was also performed at the difficult-to-return zone in Fukushima Prefecture, and the estimated dose rate distribution roughly agreed with the survey meter measurement.

Time resolution and high-counting rate performance of plastic scintillation counter with multiple MPPC readout

We have been developing a plastic scintillation counter for the WASA detector. The performance of a plastic scintillation counter with Multi-Pixel Photon Counter (MPPC) readout has been systematically investigated for minimum ionizing particles in terms of the time resolution and the signal amplitude stability. The performance was evaluated under various incident conditions of 2.5 GeV/c proton beams and with different MPPC settings. A plastic scintillator with a size of 550×38×8mm3 was optically coupled with multiple MPPCs at each plane with a size of 38×8mm2 for detecting the scintillation photons. The observed time resolution ranges in 37–80 ps (σ) depending on the incident positions and angles for the case of three MPPCs attached to each end. We found the time resolution and the signal amplitude fairly consistent up to the counting rate of 0.2 MHz.

Profile analysis of adverse events after boron neutron capture therapy for head and neck cancer: a sub-analysis of the JHN002 study.

The purpose of this study was to outline the course and profile of adverse events specific to boron neutron capture therapy (BNCT) for head and neck cancer. This was a sub-analysis of the phase II JHN002 trial. Patients received 400 mg/kg borofalan(10B), followed by neutron irradiation. The course of adverse events after BNCT was documented in the JHN002 Look Up study. Patients were grouped into face/front (FF), face/lateral (FL) and neck (N) beam groups according to the point of skin incidence of the epithermal neutron beam axis, and the profile of adverse events dependent on beam incidence position was examined. The courses of adverse events in eight recurrent squamous cell carcinoma (R-SCC) and 13 recurrent or locally advanced non-SCC cases were analyzed. Median interval to complete recovery was 23 days (interquartile range (IQR), 14–48 days) for oral mucositis, 40 days (IQR, 24–56 days) for dermatitis, 58 days (IQR, 53–80 days) for dysgeusia and 156 days (IQR, 82–163 days) for alopecia. In the FF beam group, parotitis (P = 0.007) was less frequent, while oral mucositis (P = 0.032), fatigue (P = 0.002), conjunctivitis (P = 0.001), epistaxis (P = 0.001) and abdominal discomfort (P = 0.029) tended to be more frequent than in the FL and N beam groups. Courses and irradiation site-specific profiles of adverse events in BNCT for head and neck cancer were identified. This profile may be useful for considering interventions to prevent exacerbation of treatment-related adverse events on BNCT.

Compton coincidence in silicon photon-counting CT detectors.

Purpose: Compton interactions amount to a significant fraction of the registered counts in a silicon detector. In a Compton interaction, only a part of the photon energy is deposited and a single incident photon can result in multiple counts unless tungsten shielding is used. Deep silicon has proved to be a competitive material for photon-counting CT detectors, but to improve the performance further, one possibility is to use coincidence techniques to identify Compton-scattered photons and reconstruct their incident energies. Approach: In a detector with no tungsten shielding, incident photons can interact through a series of interactions. Based on the position and energy of each interaction, probability-based methods can be used to estimate the incident photon energy. Here, we present a maximum likelihood estimation framework along with an alternative method to estimate the incident photon energy and position in a silicon detector. Results: Assuming one incident photon per time frame, we show that the incident photon energy can be estimated with a mean error of and an RMS error of for a realistic case in which we assume a detector with limited energy and spatial resolution. The interaction position was estimated with a mean error of in direction and in direction. Corresponding RMS errors of and were achieved in and , respectively. Conclusions: The presented results show the potential of using probability-based methods to improve the performance of silicon detectors for CT.

Experimental study on liquid metal free surface flow under magnetic and electric field for nuclear fusion

In the future application of nuclear fusion, the liquid metal flows are considered to be an attractive option of the first wall of the tokamak which can effectively remove impurities and improve the confinement of plasma. Moreover, the flowing liquid metal can solve the problem of the corrosion of the solid first wall due to high thermal load and particle discharge. In the magnetic confinement fusion reactor, the liquid metal flow experiences strong magnetic and electric, fields from plasma. In the present paper, an experiment has been conducted to explore the influence of electric and magnetic fields on liquid metal flow. The direction of electric current is perpendicular to that of the magnetic field direction, and thus the Lorentz force is upward or downward. A laser profilometer based on the laser triangulation technique is used to measure the thickness of the liquid film of Galinstan. The phenomenon of the liquid column from the free surface is observed by the high-speed camera under various flow rates, intensities of magnetic field and electric field. Under a constant external magnetic field, the liquid column appears at the position of the incident current once the external current exceeds a critical value, which is inversely proportional to the magnetic field. The thickness of the flowing liquid film increases with the intensities of magnetic field, electric field, and Reynolds number. The thickness of the liquid film at the incident current position reaches a maximum value when the force is upward. The distribution of liquid metal in the channel presents a parabolic shape with high central and low marginal. Additionally, the splashing, i.e. the detachment of liquid metal is not observed in the present experiment, which suggests a higher critical current for splashing to occur.

Numerical simulation of single-event effects in fully-depleted silicon-on-insulator HfO&lt;sub&gt;2&lt;/sub&gt;-based ferroelectric field-effect transistor memory cell

Ferroelectric field-effect transistor (FeFET) memory is currently a popular non-volatile memory. It has many advantages such as nonvolatility, better scalability, energy-efficient switching with non-destructive read-out and anti-radiation. To promote the application of FeFET in radiation environments, the single-event transient effect in HfO&lt;sub&gt;2&lt;/sub&gt;-based fully-depleted silicon-on-insulator (FDSOI) FeFET memory cell is studied by technology computer aided design (TCAD) numerical simulation. The effects of different incident positions and angles of heavy ions and the drain bias voltage on the characteristics of the memory cell are analyzed. The results show that the corresponding polarization state in the HfO&lt;sub&gt;2&lt;/sub&gt; ferroelectric layer will not reverse regardless of the change for the incident position of heavy ions, but the transient change of the output voltage for the memory cell will be affected. The most sensitive area is close to the drain-body junction area. Moreover, with the decrease of the ion incidence angle, the peak of output voltage for the memory cell increases. And the effect of the incident angle change is more obvious when reading data is “0” rather than “1”. The peak of output voltage for the memory cell is modulated by the drain bias voltage, and the modulation effect is more obvious when reading data is “1” rather than “0”. The above findings provide theoretical basis and guidance for the anti-single event design of the FDSOI FeFET memory cell.

Broadband angular momentum cascade via a multifocal graphene vortex generator

Light beams carrying orbital angular momentum (OAM) have inspired various advanced applications, and such abundant practical applications in turn demand complex generation and manipulation of optical vortices. Here, we propose a multifocal graphene vortex generator, which can produce broadband angular momentum cascade containing continuous integer non-diffracting vortex modes. Our device naturally embodies a continuous spiral slit vortex generator and a zone plate, which enables the generation of high-quality continuous vortex modes with deep depths of foci. Meanwhile, the generated vortex modes can be simultaneously tuned through incident wavelength and position of the focal plane. The elegant structure of the device largely improves the design efficiency and can be fabricated by laser nanofabrication in a single step. Moreover, the outstanding property of graphene may enable new possibilities in enormous practical applications, even in some harsh environments, such as aerospace.

Energy-resolved neutron imaging with glass gas electron multiplier and dynamic time-over-threshold method

Energy-resolved neutron imaging with pulsed neutron source provides quantitative neutron imaging techniques such as Bragg-edge imaging, resonance absorption imaging, and polarized neutron imaging. Micro-pattern gaseous detectors (MPGDs) such as gas electron multipliers (GEMs) are widely used in neutron detection. In this research, we will report on the first demonstration of energy-resolved neutron imaging with a glass gas electron multiplier (G-GEM) and the dynamic time-over-threshold (dToT) signal processing method. We successfully performed energy-resolved neutron imaging at J-PARC MLF by measuring incident position and the Time-of-Flight (TOF) of each neutron simultaneously.

Simulation study on photon generation and collection of tower applied to NICA-MPD electromagnetic calorimeter

Shashlik tower, which is composed of absorbers and scintillators alternately, surrounded by reflector and coupled with Silicon Photomultiplier (SiPM) by Wavelength-Shifting (WLS) fibers, is a significant component to measure the energy and position of photons and electrons in Electromagnetic Calorimeter (ECal), a key detector of the Multi Purpose Detector (MPD) at the Nuclotron-based Ion Collider facility (NICA) in Russia. In this paper, the effect of materials adopted for absorber, reflector and WLS fiber, the length and curvature of fibers and the electrons incident position on photons transmission performance of tower is simulated based on GEANT4 software. The impact of Gaussian deviation's electron beam energy and spread of 10% in the energy range on the energy resolution of tower is also studied. Results show that the low polishing degree absorber, the high polishing degree TiO_2 reflector and the type of Y-11 WLS fibers bent with a curvature radius of greater than 11 cm can significantly improve the light output. In addition, electrons injected along the centre of tower can make photons position distribution in SiPM more uniform. The generation time of photons in scintillators and time of arrival at the SiPM both obey the Landau distribution. Finally, the energy resolution of tower can be better than 3.8%/√(E) (GeV) for a Gaussian deviation's electron beam with an average energy of 3 GeV and spread of 10% in the energy range.

Simulation of the Silicon Drift Detector for the Spectroscopy Focusing Array onboard the eXTP

The Spectroscopy Focusing Array (SFA) onboard the enhanced X-ray Timing and Polarimetry observatory (eXTP) uses Silicon Drift Detectors (SDDs) at the focal plane. A simulation of the corresponding detectors is performed in this work to model the instrument responses, including the spectral and timing behaviors. It relies on the solution of the Poisson equations and the charge carrier dynamics to predict the detector performances at different X-ray incident positions. The notable features of the instrument responses are reproduced with reasonable accuracy. The simulation can be used for a variety of studies in the space mission, such as the understanding of the calibration data during on-ground tests and the verification of the scientific requirements with a certain instrument configuration. As an example, the flux limits of scientific observations are estimated in this work taking into account the pile-up and dead-time effects.

Data inversion algorithms for droplet characterization based on simulated rainbows

In characterizing droplets, the rainbow reveals information about the size of individual drops, their refractive index, temperature, and in some instances composition. Previous experience in exploiting rainbow scattering for this purpose has led to classical rainbow refractometry, but also to the global rainbow technique. To improve on these existing techniques, a highly focused Gaussian illumination beam offers some advantages for achieving higher spatial resolution in dense spray situations. This is explored in the present study, using simulations of rainbow scattering from a spherical droplet in the primary and secondary rainbow regions. These simulations are performed using the generalized Lorenz-Mie theory (GLMT), allowing for a focused Gaussian beam illumination. For droplet characterization, three inversion algorithms are investigated, designated as the peak-trough method, inflection-inflection method and trough-trough method. The effect of the incident position of the beam on the droplet characterization is considered, as are effects of white noise superimposed on the rainbow. For a spherical water droplet in the size range 50–200 μm, an accuracy of the measured relative refractive index up to 4 decimal places and a relative error in size smaller than 5% can be achieved in most cases.

Progress of lateral photovoltaic effect: theoretical models and materials

Photoelectric devices based on various theories and effects of photoelectricity have become the basic devices of human’s life, and are still a hot research field. Lateral photovoltaic effect (LPE), among significant photovoltaic mechanisms, exhibits a phenomenon in which the surface potential difference of a specific material system changes linearly with the incident laser position. Depending on this unique property, LPE has been extensively developed in position sensitive detectors (PSDs). The material and theoretical systems of LPE were constantly innovated with the emergence and continuous progress of nanotechnology and new materials. This article reviews the recent progress of LPE theory, e.g., P-N junction model and the theories based on Schottky barrier, Dambet effect, and diffusion. Meanwhile, material systems that contribute to LPE, including metal-semiconductors (MS), metal-oxide-Semiconductors (MOS), metal oxide, perovskites and organic semiconductors, are summarized as well. As an important tunning method, local surface plasmon resonance is also concerned together with some promising future of the material systems.

Slow Light Rainbow Trapping in a Uniformly Magnetized Gyromagnetic Photonic Crystal Waveguide

We present a hybrid gyromagnetic photonic crystal (GPC) waveguide composed of different GPC waveguide segments possessing various cylinder radii and waveguide widths but biased by a uniform external magnetic field. We demonstrate in frequency and time domains that based on the strong coupling of two counter-propagating topologically protected one-way edge states, the intriguing slow light rainbow trapping (SLRT) of electromagnetic (EM) waves can be achieved, that is, EM waves of different frequencies can be slowed down and trapped at different positions without cross talk and overlap. More importantly, due to the existence of one-way edge states, external EM waves can be non-reciprocally coupled to the SLRT waveguide channel, although the incident position of the EM wave is far away from the waveguide channel. Besides, the frequency range of the slow light states can also be easily regulated by tuning the intensity of an external magnetic field, which is very beneficial to solve the contradiction between slow light and broad bandwidth. Our results can be applied to the design of high-performance photonic devices, such as an optical buffer, optical switch, and optical filter.