Particles In Field Research Articles

CosmiXs: cosmic messenger spectra for indirect dark matter searches

The energy spectra of particles produced from dark matter (DM) annihilation or decay are one of the fundamental ingredients to calculate the predicted fluxes of cosmic rays and radiation searched for in indirect DM detection. We revisit the calculation of the source spectra for annihilating and decaying DM using the Vincia shower algorithm in Pythia to include QED and QCD final state radiation and diagrams for the EW corrections with massive bosons, not present in the default Pythia shower model. We take into account the spin information of the particles during the entire EW shower and the off-shell contributions from massive gauge bosons. Furthermore, we perform a dedicated tuning of the Vincia and Pythia parameters to LEP data on the production of pions, photons, and hyperons at the Z resonance and discuss the underlying uncertainties. To enable the use of our results in DM studies, we provide the tabulated source spectra for the most relevant cosmic messenger particles, namely antiprotons, positrons, γ rays and the three neutrino flavors, for all the fermionic and bosonic channels and DM masses between 5 GeV and 100 TeV, on github.

Design of new zwitterionic microparticles with intrinsic antibacterial activity

AbstractThe crosslinked porous microparticles based on glycidyl methacrylate, N‐vinylimidazole, and triethylene glycol dimethacrylate (molar ratio between monomers 40:30:30) obtained in the presence of three porogenic agents (toluene, n‐butyl acetate, and toluene:n‐butyl acetate mixture, 1:1, v/v) are used as precursors in the polymer analogous reactions with some betainizing agents (sodium monochloroacetate, acrylic acid, methacrylic acid and 1,3–propane sultone) in order to introduce the carboxybetaine/sulfobetaine groups to the tertiary nitrogen atom from the imidazole ring. ATR–FTIR spectroscopy is used to highlight the presence of carboxybetaine/sulfobetaine groups on the structure of the microparticles, but also to calculate the degree of betainization (55.91%–90.2%) The zwitterionic microparticles are characterized by scanning electron and atomic force microscopies, equilibrium swelling ratio as a function of pH values, swelling kinetics, ion exchange capacities and particle size distribution. Also, the parameters of porous structure (pore diameter, pore volume, porosity, and specific surface area) are determined by mercury porosimetry. The antibacterial properties of Gram‐positive (Enterococcus faecalis and Staphylococcus aureus) and Gram‐negative (Escherichia coli and Klebsiella pneumoniae) bacteria are evaluated. It is found that the zwitterionic structures containing a shorter length alkyl chain between ionic groups exhibit excellent antibacterial activity of about 80%–92%.

Parameters affecting plug characteristics in dense phase pneumatic conveying of ellipsoidal particles

Even though particle shape tends to have a major influence on the bulk behaviour of a granular system, perfectly spherical particles are often used in numerical simulations. In this study, we examine the plug flow of ellipsoidal particles in dense phase horizontal pneumatic conveying within a rigid and cylindrical pipe with periodic boundaries in the axial direction. We use coupled Computational Fluid Dynamics (CFD) – Discrete Element Method (DEM) simulations to investigate the effect of particle shape on four plug characteristics: velocity, length, porosity, and particle exchange rate with the stationary bed. Both ellipsoidal and spherical particles are used, and the parameters varied are the particle size, aspect ratio, pressure gradient, particle–particle and particle–wall sliding and rolling friction coefficients, and coefficients of restitution. The steady state characteristics of plugs composed of spherical particles are distinctly different from those composed of ellipsoidal particles. Certain parameters, including the particle–wall rolling friction and restitution coefficients, have minimal impact on the steady state plug characteristics. The present study also suggests that introducing interparticle rolling friction for perfectly spherical particles can achieve the velocity and length appropriate for plugs composed of ellipsoidal particles, although differences in dynamics may persist. Overall, this comprehensive analysis offers valuable insights into plug flow behaviour with non-spherical particles, aiding in the efficient modelling and design of pneumatic conveying systems.

An effective approach for aerosol dynamics modeling in dusty plasma

In this paper, we demonstrate the application of the Dirac-lognormal bimodal moment approach to investigate aerosol dynamics in dusty plasmas. This approach was evaluated by comparison with the detailed and computationally expensive sectional approach for two dusty plasma systems. The first one is a sputtering Argon DC discharge and the second is a capacitively coupled Ar/C2H2 radio-frequency (CCRF) discharge. The results obtained by the bimodal and the sectional approaches are in good agreement for the sputtering DC discharge where the aerosol dynamics is dominated by nucleation and surface deposition growth processes. This agreement is obtained not only on the averaged characteristics of the particle cloud, but also on the detailed particle size distributions. In the case of the CCRF discharge a satisfactory agreement between the two approaches is obtained on the averaged characteristics and on the core distributions of the particle cloud even if a significant difference is observed at low and intermediate particle size. Nevertheless, the bimodal moment approach is accurate enough for the simulation of the dusty plasmas of interest. Its low-computational cost makes it a very effective method as far as dusty plasma simulation is concerned.

Hunting muonic forces at emulsion detectors

Only two types of Standard Model particles are able to propagate the 480meters separating the ATLAS interaction point and FASER: neutrinos and muons. Furthermore, muons are copiously produced in proton collisions. We propose to use FASERν as a muon fixed target experiment in order to search for new bosonic degrees of freedom coupled predominantly to muons. These muon force carriers are particularly interesting in light of the recent measurement of the muon anomalous magnetic moment. Using a novel analysis technique, we show that even in the current LHC run, FASERν could potentially probe previously unexplored parts of the parameter space. In the high-luminosity phase of the LHC, we find that the improved sensitivity of FASERν2 will probe unexplored parameter space and may be competitive with dedicated search proposals. Published by the American Physical Society 2024

Constraints between entropy production and its fluctuations in nonthermal engines

We analyze a mesoscopic conductor autonomously performing a thermodynamically useful task, such as cooling or producing electrical power, in a part of the system—the working substance—by exploiting another terminal or set of terminals—the resource—that contains a stationary nonthermal (nonequilibrium) distribution. Thanks to the nonthermal properties of the resource, no exchange of particles or energy with the working substance is required to fulfill the task. This resembles the action of a , as long as only average quantities are considered. Here, we go beyond a description based on average currents and investigate the role of fluctuations in such a system. We show that a minimum level of entropy fluctuations in the system is necessary, whenever one is exploiting a certain entropy production in the resource terminal to perform a useful task in the working substance. For concrete implementations of the demonic nonthermal engine in three- and four-terminal electronic conductors in the quantum Hall regime, we compare the resource fluctuations to the entropy production in the resource and to the useful engine output (produced power or cooling power). Published by the American Physical Society 2024

Abnormal states with unequal constituent masses

The Bethe–Salpeter equation for system of two oppositely charged particles not only reproduces the Coulomb spectrum, but, for enough large coupling constant C>π4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathcal C}>\\frac{\\pi }{4}$$\\end{document}, predicts additional levels not predicted by the Schrödinger equation. These relativistic states (called abnormal), in contrast to the normal ones, are dominated, for more than 90–99%, by Fock states involving the exchange particles—the photons, whereas contribution of two massive charged particles themselves is rather small (1–10%). Since the carrier of a large (positive) charge is a heavy ion, and the negative charge is provided by electron, the masses of two constituents are very different. It is shown that in a system with so different masses the abnormal states still exist. Moreover, the effect of unequal masses is attractive. The balance between photons and charged constituents is weakly sensitive to the mass ratio, so the photons still predominate.

Sediment source variation using REEs, Sr, and Nd isotopic compositions: a case study in MD05-2901, northwestern South China Sea

The South China Sea (SCS) is the largest marginal sea in the western Pacific, fed by large Asian rivers, characterized by substantial volumes of sediment derived from surrounding Asian continents and islands. This study utilizes the rare earth elements (REEs), Sr isotopes (87Sr/86Sr), and Nd isotopes (ƐNd) in detritus fractions of MD05-2901 sediments in northwestern SCS, to evaluate the relative contribution among the Mekong River, the Red River, the Pearl River, and rivers in SW Taiwan over the last 32 ka. This deep-sea core is located off the coast of central Vietnam, an upwelling region with only minor continental inputs, and this study is important for a better understanding of the main sources of terrigenous material and their temporal variations in the region. In addition, potential particle exchange is examined using the same proxies in the Fe-Mn oxyhydroxide fractions. The obtained records are systematically compared with the available climatic archives in the region. The REEs in the Fe-Mn oxyhydroxides support the argument of water mass signature separation in bulk sediments by chemical leaching procedures. These 87Sr/86Sr in the Fe-Mn oxyhydroxides phase fall in a range between 0.709262 and 0.709313, deviating significantly from the modern seawater. ƐNd values vary >3Ɛ, being more radiogenic in the Fe-Mn oxyhydroxides, where the lowest value occurred in the Bølling/Allerød (B/A) and higher values occurred during the Younger Dryas (YD). The latter implies increased contribution of loess dusts or Taiwanese rivers under dry/cold climatic conditions, compared with the situation in modern times. The Red River and the Mekong River together may have contributed >60% during the Last Glacial Maximum (LGM) and YD. In contrast, the Pearl River components have increased sharply to ~60% during the warm B/A. These results demonstrate that the MD05-2901 sediments sensitively record changes in weathering intensity on land and transport pathways in the coastal regions in the Holocene.

Vortex-induced particle capture in a micro cross-shaped channel

Vortex-induced particle capture has attracted widespread attention as an effective tool for particle preconcentration or manipulation. In this work, the motion and capture of particles in confined vortices in a micro cross-shaped channel are explored by a high-speed camera within Reynolds numbers ranging from 10 to 450. Micro Laser-Induced Fluorescence (μLIF) and numerical simulation are used to visualize flow structures. Results demonstrate that a buoyant particle undergoes an attenuation oscillation, finally arriving a periodic orbit (i.e., a limit cycle) inside the vortex. The formation of the orbit is closely associated with the development of recirculating flows in the microchannel. With an increase in the number of captured particles, the average distributions of particles show particle exchange corridors between capture regions and mainstream, which is caused by interactions between particles or flow instability. Once the particle density exceeds the fluid density, the particle periodic orbits disappear, and particles move directly or spirally to the outlets. Moreover, oscillation induced by vortex merging and splitting influences the quantities and distributions of capture regions, as well as the migration paths of buoyant particles. In addition to particle capture at the channel center, a portion of captured particles is observed near channel walls.

Advanced Intrusion Detection in Vehicular Networks: Empowering Security through Hybrid Off-loading Techniques and Enhanced Radial Bias Neural Network

Over the last several decades, the implementation of ITS has shown to be the most efficient and successful strategy for expanding the variety of current transportation networks. Vehicle-based offloading of data going to be essential for forthcoming networking innovations like D2D and 5G due to the substantial contribution it makes to efficiently using network capability while wasting minimal power. Information transmissions that would normally need a cellular network's infrastructure may instead be made using alternative networking mechanisms including Bluetooth, WiFi, and opportunistic communications. Data offloading has the ability to significantly increase the efficiency with which network resources are used. The offloading of data from vehicles has a considerable impact on the strain on cellular networks. It helps the network achieve higher throughput by facilitating the simultaneous reception of data by a large number of users. First, we must establish that the problem of Vehicular data offloading is an NP-hard target set selection (TSS) issue before we can even begin to characterize it. Using a combination of Hybrid PSO and GWO, TSS selects a small group of nodes to do the redundant data exchange (Particle Swarm Optimization with Gray Wolf Optimization). Collaboration between individuals and ISPs to identify effective aim sets may provide useful insights. If malicious users are present in the target group, they may slow down network activity by spoofing or by reducing the network's offloading capacity. It is possible that the whole network's performance would suffer as a direct result of these malicious users. In this study, we suggest a hybrid approach to communication for specifying the intended audience. We take use of the characteristics of opinion dynamics amongst users to get around the issue of overlapping community detection. Trust-based metrics inferred from users' activities are used to ensure the safety of the target set. In order to call 911, the suggested work additionally incorporates a method of sorting and classifying the offload limitations through Radial Bias Neural Network (RBNN). The following may be determined with the use of the proposed work's performance indicators: precision, entropy, and delay.

Subphotospheric Emission from Short Gamma-Ray Bursts: Protons Mold the Multimessenger Signals

The origin of the observed Band-like photon spectrum in short gamma-ray bursts (sGRBs) is a long-standing mystery. We carry out the first general relativistic magnetohydrodynamic simulation of an sGRB jet with initial magnetization σ 0 = 150 in dynamical ejecta from a binary merger. From this simulation, we identify regions along the jet of efficient energy dissipation due to magnetic reconnection and collisionless subshocks. Taking into account electron and proton acceleration processes, we solve for the first time the coupled transport equations for photons, electrons, protons, neutrinos, and intermediate particle species up to close to the photosphere (i.e., up to 1 × 1012 cm), accounting for all relevant radiative and cooling processes. We find that the subphotospheric multimessenger signals carry strong signatures of the hadronic interactions and their resulting particle cascades. Importantly, the spectral energy distribution of photons is significantly distorted with respect to the Wien one, commonly assumed below the photosphere. Our findings suggest that the bulk of the nonthermal photon spectrum observed in sGRBs can stem from hadronic processes occurring below the photosphere and previously neglected, with an accompanying energy flux of neutrinos peaking in the GeV energy range.

Influence of particle size on the separation performance and flotation kinetics of foundry dust

The high-efficiency separation of foundry dust (FD) is imperative for its resource utilization, which contributes to promoting cleaner production and environmental protection in the foundry industry. In order to strengthen the flotation performance of high-quality coal dust in the FD, a systematized investigation was carried out to explore the influence of particle size on the contact angle, separation performance, and flotation kinetics of the FD. The results indicate that the pretreatment process increases the contact angle of the FD, and the liberation degree of coal dust decreases with the decrease of particle size. The fine particles of −53 µm can reduce the separation performance, resulting in a lower coal dust recovery of 60.79%. The coarse particles of −212 + 75 µm and intermediate particles of 75–53 µm possess better flotation results compared to the unclassified FD. The coal dust recovery in the coarse particles can reach up to 84.68%, and the obtained coal dust exhibits a pristine surface and splendid purity. The results of flotation kinetics analysis found that classical first-order model is suitable for characterizing flotation process of the FD with different particle sizes. The flotation rate constant drops as particle size reduces, revealing that the floatability of FD can be significantly improved via a classification method. This may provide a valuable method and scientific guidance for efficient separation and resource utilization of the FD.

About elementary particles

It is shown that only stable particles can be elementary particles. The fundamental elementary particles are positive, negative and neutral particles of space. Photons and neutrinos are formed from them, which are elementary particles of electrons, positrons and protons. A neutral photon consists of a positive elementary particle of space, around which a negative elementary particle of space rotates. A neutrino consists of a negative elementary particle of space, around which a positive elementary particle of space rotates. An electron has a structure consisting of negative and neutral photons connected by negative elementary particles of space. The positron has a structure consisting of positive and neutral photons connected by negative elementary particles of space. A proton consists of a positively charged nucleus around which electrons rotate. The proton nucleus consists of positrons bound by neutrino particles. Atomic nuclei consist of positive and neutral protons connected by the exchange of electrons and neutrino particles. The carriers of electromagnetic interaction are positive and negative elementary particles of space. The carriers of the gravitational interaction are neutral elementary particles of space. Electromagnetic, gravitational and inertial forces are the forces of space. Space is an equilibrium system, just like the whole universe.

Effect of Flour Particle Size on the Glycemic Index of Muffins Made from Whole Sorghum, Whole Corn, Brown Rice, Whole Wheat, or Refined Wheat Flours.

The unique properties of sorghum are increasingly being studied for potential health benefits, with one area of emphasis being the impact of sorghum consumption on mitigating type 2 diabetes. The glycemic index (GI) of muffins made from whole grain sorghum flour ground to three different particle sizes (fine, intermediate, coarse) was tested on eight healthy volunteers (ages 18-40) and compared to the glycemic index of whole grain corn, wheat, and rice flours produced using a similar product formula. Sorghum flour ground through a 0.5 mm screen ("fine") had an overall similar particle size to that of the brown rice flour ground using a 0.5 mm screen. The range of GI values was 32 to 56, with only the GI of intermediate milled sorghum flour being lower than that of corn, rice, or wheat (p < 0.05). The lowest glycemic index (32 +/- 17) was found when using sorghum flour with an intermediate particle size (167 +/- 4 μm). Muffins made using brown rice had the next lowest glycemic index at 37 +/- 17. All GI values calculated had large standard deviations, which is common for these types of studies. These results can assist in the product development process to advance the quality of healthy, gluten-free sorghum-based foods for consumers. Further research should investigate if these results can be duplicated and the possible reason for the lower GI of intermediate particle size sorghum flour.

Nonequilibrium steady states in coupled asymmetric and symmetric exclusion processes.

We propose and study a one-dimensional (1D) model consisting of two lanes with open boundaries. One of the lanes executes diffusive and the other lane driven unidirectional or asymmetric exclusion dynamics, which are mutually coupled through particle exchanges in the bulk. We elucidate the generic nonuniform steady states in this model. We show that in a parameter regime, where hopping along the TASEP lane, diffusion along the SEP lane, and the exchange of particles between the TASEP and SEP lanes compete, the SEP diffusivity D appears as a tuning parameter for both the SEP and TASEP densities for a given exchange rate in the nonequilibrium steady states of this model. Indeed, D can be tuned to achieve phase coexistence in the asymmetric exclusion dynamics together with spatially smoothly varying density in the diffusive dynamics in the steady state. We obtain phase diagrams of the model using mean field theories, and corroborate and complement the results with stochastic Monte Carlo simulations. This model reduces to an isolated open totally asymmetric exclusion process (TASEP) and an open TASEP with bulk particle nonconserving Langmuir kinetics (LK), respectively, in the limits of vanishing and diverging particle diffusivity in the lane executing diffusive dynamics. Thus, this model works as an overarching general model, connecting both pure TASEPs and TASEPs with LK in different asymptotic limits. We further define phases in the SEP and obtain phase diagrams and show their correspondence with the TASEP phases. In addition to its significance as a 1D driven, diffusive model, this model also serves as a simple reduced model for cell biological transport by molecular motors undergoing diffusive and directed motion inside eukaryotic cells.

The neutral current deeply inelastic scattering process and a revisit on the intrinsic asymmetry

The intermediate particle in the neutral current deeply inelastic scattering process can be either a virtual photon or a Z0 boson. In this paper we calculate contributions from the weak interaction in the semi-inclusive deeply inelastic scattering process. Semi-inclusive implies that a jet in the current region is also measured in addition to the scattered electron. Jet can be a good candidate to study the three-dimensional structure of the nucleon in the semi-inclusive deeply inelastic scattering process. In the vector boson-nucleon collinear frame, the transverse momentum of the jet is the same to that of the quark in the nucleon under the leading order approximation. As a result, one can define the intrinsic asymmetry which reveals the imbalance of the transverse momentum of the incident quark to explore the transverse momentum dependent parton distribution functions (TMD PDFs). With the Gaussian ansatz for the TMD PDFs, we restudy the transverse momentum dependent behavior of the intrinsic asymmetry. We find that the asymmetry tends to a linear function with respect to k⊥ when Δu,d2 approach Δ′u,d2.

Application of radiotracers as tools to determine feed flowrate imbalances and particle size segregation in industrial flotation circuits

This publication presents the application of radiotracers in the characterization of industrial flotation circuits. Two examples are showcased: the detection of feed flow rate imbalances and the characterization of particle size segregation in automatic mineral-cutting machines. The feed pulp distribution was determined from the mean residence times. Particle size segregation was measured by sampling the cutting machines (≅ 25 grams samples) using coarse, intermediate, and fine-sized radiotracer particles. Radiotracers were injected into the feed streams and measured at various points of the circuit using nuclear instruments, allowing for non-invasive and real time detection. Results show that in the rougher flotation stage, the feed flow is distributed almost evenly in lines 2 and 3 (approximately 38% of the flow goes to each line) and to a lesser extent towards line 4 (approximately 24%). In lines 1 and 2 of the scavenger stage, a higher percentage of the flow goes towards line 1 (approximately 59%) and a lower percentage towards line 2 (41%). Line 6 of the rougher flotation is the fastest of the circuit (shortest residence time). In addition, the inlet mineral-cutting machine of the rougher stage segregates particles with a bias for fine sizes (11.4 % more fine-sized particles than coarse ones). This work is an example of how radiotracer technology can be applied to improve metal production and processes. Radiotracers provide reliable information to be used in combination with other metallurgical data to properly assess flotation circuits.

Hanle effect in transport through single atoms in spin-polarized STM

Following recent achievements in quantum-coherent manipulation and detection of individual atomic spins with the use of spin-polarized scanning tunneling microscope, we propose how to observe and utilize the Hanle effect in electronic transport in such setups. We show that the Hanle experiment can be used to observe the single spin precession driven by the intrinsic exchange field. This field is a result of virtual particle exchange processes, and its magnitude and sign can be controlled electrically. We also show that from detailed analysis of the Hanle resonance curve one can determine the spin relaxation time from dc current measurements.

Enhancing state and parameter estimations of a dynamic crop model by a recombination particle filter

Crop simulation models are essential tools in supporting sustainable agricultural management. However, due to uncertainty in model parameters, the model predictions may not be sufficiently accurate. Data assimilation (DA) is a common approach to improve dynamic crop modeling by combining it with observation data. Among DA approaches, particle filter (PF) is a popular choice. Since conventional PF (CPF) may suffer from sample impoverishment problems, various filter modifications have been proposed in the literature, including the application of genetic operators (arithmetic cross-over and mutations). In this study, a novel PF approach inspired by the gene’s recombination process has been developed. In this new filter, named “recombination” PF (RPF), particle diversity is increased via information exchange between surviving particles and intermediate particles which are located close to existing particles. In turn, increased particle diversity reduces the chances of sample impoverishment and thus improves filter performance. The proposed method was tested on two synthetic study cases using the open-source AquaCrop model (v5.0a) and assuming weekly observations of canopy cover and soil water content. When CPF was implemented, the overall average normalized root mean square error (NRMSE), combining state and parameter estimations, and yield forecasts, all performed throughout the season, ranged from 4.0 to 5.1 % for ensemble sizes ranging from 150 to 500 particles. When RPF was implemented with a similar number of particles, the overall average NRMSE decreased to 3.6–3.7 %, corresponding to a 7–26 % improvement. Furthermore, higher stability of the results was observed, and the final parameter estimations improved in all the ensemble sizes investigated by approximately 40 %, which would be very beneficial for predicting crop growth in the next season.

Salinity Changes and Bottom Water Particle Exchange Simulations in Response to Sluice Gate Operations at Saemangeum Lake

Salinity Changes and Bottom Water Particle Exchange Simulations in Response to Sluice Gate Operations at Saemangeum Lake