Coalescence Parameters Research Articles

Mini-batch settling cell for investigation of liquid-liquid phase separation

The performance of the phase separation, particularly the sedimentation and coalescence behavior is pivotal for the efficiency of the process design of a gravity settler. Given the significant parameter space involved, a new approach for batch-settling experiments is presented. Compared to a commonly used liter-scale batch-settling cell, the new cell requires a small volume of 21 ml and enables parallelization of up to 20 experiments. These are compared with the data from the common cell to evaluate the quality of the measurement data generated with the new cell. For this purpose, Sauter mean diameters and coalescence parameters are determined for standard test systems with the new and the common cells and used to design a settler. The mini-batch settling cell not only qualitatively describes the settling behavior but can also be used for designing a settler with the same accuracy as the common cell.

An Evaluation and Improvement of Microphysical Parameterization for a Heavy Rainfall Process during the Meiyu Season

The present study assesses the simulated precipitation and cloud properties using three microphysics schemes (Morrison, Thompson and MY) implemented in the Weather Research and Forecasting model. The precipitation, differential reflectivity (ZDR), specific differential phase (KDP) and mass-weighted mean diameter of raindrops (Dm) are compared with measurements from a heavy rainfall event that occurred on 27 June 2020 during the Integrative Monsoon Frontal Rainfall Experiment (IMFRE). The results indicate that all three microphysics schemes generally capture the characteristics of rainfall, ZDR, KDP and Dm, but tend to overestimate their intensity. To enhance the model performance, adjustments are made based on the MY scheme, which exhibited the best performance. Specifically, the overall coalescence and collision parameter (Ec) is reduced, which effectively decreases Dm and makes it more consistent with observations. Generally, reducing Ec leads to an increase in the simulated content (Qr) and number concentration (Nr) of raindrops across most time steps and altitudes. With a smaller Ec, the impact of microphysical processes on Nr and Qr varies with time and altitude. Generally, the autoconversion of droplets to raindrops primarily contributes to Nr, while the accretion of cloud droplets by raindrops plays a more significant role in increasing Qr. In this study, it is emphasized that even if the precipitation characteristics could be adequately reproduced, accurately simulating microphysical characteristics remains challenging and it still needs adjustments in the most physically based parameterizations to achieve more accurate simulation.

Searching for enhancement in coalescence of in-jet (anti-)deuterons in proton-proton collisions

Recent measurements from ALICE report that “in-jet” nucleons carry a higher probability of forming a deuteron via coalescence than the nucleons from the underlying event (UE). This study makes use of an event shape classifier to separate the “in-jet” deuterons and the deuterons in the UE produced in high multiplicity proton-proton collisions at s=13 TeV. Event shape variables such as transverse spherocity allow the categorization of hard and soft components of an event, which can be divided into two respective classes; “jetty” and “isotropic”. The “jetty” deuterons minus the contribution of the deuterons from the “isotropic” event are taken as “in-jet” deuterons, and the coalescence mechanism is tested. The coalescence is performed with a Wigner function formalism, augmented as an afterburner to . The possible enhancement of the coalescence probability of “in-jet” deuterons is investigated by calculating the coalescence parameter (B2) in different spherocity classes in high-multiplicity pp collisions. Published by the American Physical Society 2024

Measurement of the production of (anti)nuclei in p–Pb collisions at [formula omitted

Measurements of (anti)proton, (anti)deuteron, and (anti)3He production in the rapidity range −1<y<0 as a function of the transverse momentum and event multiplicity in p–Pb collisions at a center-of-mass energy per nucleon–nucleon pair sNN=8.16TeV are presented. The coalescence parameters B2 and B3, measured as a function of the transverse momentum per nucleon and of the mean charged-particle multiplicity density, confirm a smooth evolution from low to high multiplicity across different collision systems and energies. The ratios between (anti)deuteron and (anti)3He yields and those of (anti)protons are also reported as a function of the mean charged-particle multiplicity density. A comparison with the predictions of the statistical hadronization and coalescence models for different collision systems and center-of-mass energies favors the coalescence description for the deuteron-to-proton yield ratio with respect to the canonical statistical model.

Design of a Modified Coupled Resonators Optical Waveguide Supporting a Frozen Mode

We design a three-way silicon optical waveguide with the Bloch dispersion relation supporting a stationary inflection point (SIP). The SIP is a third order exceptional point of degeneracy (EPD) where three Bloch modes coalesce forming the frozen mode with greatly enhanced amplitude. The proposed design consists of a coupled resonators optical waveguide (CROW) coupled to a parallel straight waveguide. At any given frequency, this structure supports three pairs of reciprocal Bloch eigenmodes, propagating and/or evanescent. In addition to full-wave simulations, we also employ a so-called “hybrid model” that uses transfer matrices obtained from full-wave simulations of sub-blocks of the unit cell. This allows us to account for radiation losses and enables a design procedure based on minimizing the eigenmodes’ coalescence parameter. The proposed finite-length CROW displays almost unitary transfer function at the SIP resonance, implying a nearly perfect conversion of the input light into the frozen mode. The group delay and the effective quality factor at the SIP resonance show an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> scaling, where <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> is the number of unit cells in the cavity. The frozen mode in the CROW can be utilized in various applications like sensors, lasers and optical delay lines.

Enhanced Deuteron Coalescence Probability in Jets.

The transverse-momentum (p_{T}) spectra and coalescence parameters B_{2} of (anti)deuterons are measured in p-p collisions at sqrt[s]=13 TeV for the first time in and out of jets. In this measurement, the direction of the leading particle with the highest p_{T} in the event (p_{T}^{lead}>5 GeV/c) is used as an approximation for the jet axis. The event is consequently divided into three azimuthal regions, and the jet signal is obtained as the difference between the toward region, that contains jet fragmentation products in addition to the underlying event (UE), and the transverse region, which is dominated by the UE. The coalescence parameter in the jet is found to be approximately a factor of 10 larger than that in the underlying event. This experimental observation is consistent with the coalescence picture and can be attributed to the smaller average phase-space distance between nucleons in the jet cone as compared with the underlying event. The results presented in this Letter are compared to predictions from a simple nucleon coalescence model, where the phase-space distributions of nucleons are generated using pythia8 with the Monash 2013 tuning, and to predictions from a deuteron production model based on ordinary nuclear reactions with parametrized energy-dependent cross sections tuned on data. The latter model is implemented in pythia8.3. Both models reproduce the observed large difference between in-jet and out-of-jet coalescence parameters, although the almost flat trend of the B_{2}^{Jet} is not reproduced by the models, which instead give a decreasing trend.

Light (anti)nuclei production in Pb-Pb collisions at sNN=5.02 TeV

The measurement of the production of deuterons, tritons and He3 and their antiparticles in Pb-Pb collisions at sNN=5.02TeV is presented in this article. The measurements are carried out at midrapidity (|y|< 0.5) as a function of collision centrality using the ALICE detector. The pT-integrated yields, the coalescence parameters and the ratios to protons and antiprotons are reported and compared with nucleosynthesis models. The comparison of these results in different collision systems at different center-of-mass collision energies reveals a suppression of nucleus production in small systems. In the Statistical Hadronisation Model framework, this can be explained by a small correlation volume where the baryon number is conserved, as already shown in previous fluctuation analyses. However, a different size of the correlation volume is required to describe the proton yields in the same data sets. The coalescence model can describe this suppression by the fact that the wave functions of the nuclei are large and the fireball size starts to become comparable and even much smaller than the actual nucleus at low multiplicities.Received 10 February 2023Accepted 16 May 2023DOI:https://doi.org/10.1103/PhysRevC.107.064904Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.©2023 CERN, for the ALICE CollaborationPhysics Subject Headings (PhySH)Research AreasParticle & resonance productionParticle correlations & fluctuationsRelativistic heavy-ion collisionsPropertiesA ≤ 5Accelerators & BeamsNuclear Physics

Exploring light nuclei production at RHIC and LHC energies with A Multi-Phase Transport model and a coalescence afterburner

In heavy-ion collisions, understanding how light nuclei species are produced can provide insight into the nature of hadronic interactions in extreme conditions. It can also shed light on understanding the matter-antimatter asymmetry and dark matter searches in astrophysical processes. To investigate the production mechanism of light nuclei such as deuteron, triton, and helium-3, we use a naive coalescence afterburner coupled to the well-known “A Multi-Phase Transport model” (AMPT). We focus on studying the production of light nuclei in central Au+Au collisions at different center of mass energies (sNN = 19.6, 39, and 200 GeV) and in Pb+Pb collisions at sNN = 2.76 TeV, at mid-rapidity. We generate events with the string melting version of AMPT, and feed the information of the nucleons with spatial and momentum conditions into the coalescence afterburner. Our study reports differential and integrated yields in transverse momentum (pT) of the light nuclei in different center of mass energies. We also estimate the coalescence parameters (BA) as a function of pT and collision energy for (anti-)deuterons, tritons and helium-3s for Au+Au and Pb+Pb collisions, which are compared to other light nuclei production studies. All results are compared with measurements from the STAR and ALICE experiments.

Light nuclei production in Au+Au collisions at 3 GeV from coalescence model* *Supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB34000000) and the National Natural Science Foundation of China (12205342)

The nucleon coalescence model is one of the most popular theoretical models for light nuclei production in high-energy heavy-ion collisions. The production of light nuclei d, t, He, and He is studied using the transport model JAM with a simplified afterburner coalescence at GeV Au+Au collisions. We scan the cut-off of phenomenological coalescence parameters, i.e., the relative spatial distance and momentum difference , for the formation of light nuclei by nucleon coalescence to reproduce the light nuclei spectra measured by the STAR experiment. The results indicate a potential connection between the coalescence parameters and the binding energy as well as the diameter of these light nuclei.

Frozen mode regime in an optical waveguide with a distributed Bragg reflector

We introduce a glide symmetric optical waveguide exhibiting a stationary inflection point (SIP) in the Bloch wavenumber dispersion relation. An SIP is a third-order exceptional point of degeneracy (EPD) where three Bloch eigenmodes coalesce to form a so-called frozen mode with vanishing group velocity and diverging amplitude. We show that the incorporation of chirped distributed Bragg reflectors and distributed coupling between waveguides in the periodic structure facilitates the SIP formation and greatly enhances the characteristics of the frozen mode regime. We confirm the existence of an SIP in two ways: by observing the flatness of the dispersion diagram and also by using a coalescence parameter describing the separation of the three eigenvectors collapsing on each other. We find that, in the absence of losses, both the quality factor and the group delay at the SIP grow with the cubic power of the cavity length. The frozen mode regime can be very attractive for light amplification and lasing in optical delay lines, sensors, and modulators.

A percolation model of fly ash formation during the combustion of non-uniform porous char

An improved percolation model has been introduced to predict the particle size distributions (PSDs) of produced residue during pulverized coal char combustion. A three-dimensional cluster of interconnected sites representing a single char particle is constructed at a given size. These sites are classified into surrounding gas, macropores, carbon, or ash. Non-uniform porous char structures and the melting performances of the ash particle have been considered to approach the most realistic scenario. The char fragmentation and ash coalescence process is simulated by checking the connectivity and proximity of occupied sites. The effects of char particle sizes are addressed by using char PSD data as the input to the model. The numerical results were compared with the measured PSDs of fly ash and show a good agreement. The effects of porous char structure and included minerals on the sizes of produced particles during combustion are further investigated. The simulation results indicate that the mean sizes of produced particles initially decrease (N<0.7) and then increase with char consumption. The char fragmentation behavior dominates in the preliminary and middle stages of char burning, while the ash coalescence is the primary behavior in the char burnout stage. The mean sizes of produced particles increase with the lower char porosity and the higher extent of pore aggregation. The size difference between PM20 and PM20+ increases when the macropores are repositioned to be aggregated. The mean sizes are positively related to the ash content and ash coalescence parameter in the middle and late stages of char burning.

Results on light (anti)nuclei production in Pb–Pb collisions with ALICE at the LHC

The high collision energies reached at the LHC lead to significant production yields of light (anti)nuclei in proton-proton, p–Pb and Pb–Pb collisions. Light (anti)nuclei are identified using their specific energy loss (dE/dx), measured in the Time Projection Chamber, and their velocity using the Time-Of-Flight detector. The excellent tracking and particle identification capabilities of the ALICE experiment, as well as its low material budget, make this detector unique for measurements of these rarely produced particles. Results on (anti)deuteron, (anti)triton, (anti)3He and (anti) He production in Pb–Pb collisions at p sNN = 5.02 TeV, including their transverse momentum (pT) spectra, production yields and coalescence parameters BA, are presented. These results will be compared to the expectations of coalescence and statistical hadronization models to obtain information on the production mechanism of light (anti)nuclei in heavy-ion collisions. Furthermore, the first measurements of the d and 3He absorption cross section are shown.

Parameter Optimization of Catering Oil Droplet Electrostatic Coalescence under Coupling Field with COMSOL Software

At present, the common cooking fume purification devices are mostly based on electrostatic technology. There are few researches on the microscopic process of coalescence and electric field parameters’ optimization. In this paper, COMSOL MultiphysicsTM was used to simulate the electrostatic coalescence of oil droplets in the coupling field of an electric field and flow field. The degree of deformation of oil droplets (D) and the starting coalescence time (tsc) were used to evaluate the coalescence process. The feasibility of the model was verified through experimental results. The effects of voltage, flow speed and oil droplet radius on tsc were investigated, and the parameters were optimized by the response surface method and Matrix correlation analysis. It can be concluded that increasing the voltage, flow speed and oil droplet radius appropriately would be conducive to the coalescence of oil droplets. When the oil droplet radius was in the range of 0–1.5 mm, it promoted the coalescence of oil droplets. The influence of various factors on oil droplet coalescence was flow speed &gt; voltage &gt; oil droplet radius. The optimal result obtained by simulation was that when the radius of the oil droplet was 1.56 mm, the voltage 12 kV and the flow speed 180 mm/ms, the shortest coalescence time of oil droplets was 16.8253 ms.

Study of nuclear modification factors of deuteron and anti-deuteron in Pb\u2013Pb collisions at sqrt{s_{mathrm{NN}}} =2.76,hbox {TeV}

The nuclear modification factors (R_{AA}) of d and bar{d} have been studied using the parton and hadron cascade model plus the dynamically constrained phase space coalescence model in peripheral (40–60%) and central (0–5%) Pb–Pb collisions at sqrt{s_{NN}}=2.76,hbox {TeV} with |y|<0.5, p_T<20.0 ,hbox {GeV}/hbox {c}. It is found that the R_{AA} of d, bar{d} is similar to that of hadrons (pi ^pm , p, bar{p}) and the R_{AA} of antiparticles is the same as that of particles. The suppression effect of d is more significant than that of baryons and mesons in the high-p_T region. The suppression of R_{AA} at high-p_T strongly depends on event centrality and mass of the particles, i.e., the central collision is more suppressed than the peripheral collision. Besides, the yield ratios and double ratios for different particle species, and the coalescence parameter B_2 for (d, bar{d}) in pp and Pb–Pb collisions are discussed, respectively. It is observed that the yield ratios and double ratios of d to p and p to pi are similar to those of their anti-particles in three different collision systems, suggesting that the suppressions of matter (pi ^{+}, p, d) and the corresponding antimatter (pi ^{-},bar{p},bar{d}) are around the same level.

Production of light (anti)nuclei in pp collisions at sqrt{s} = 13 TeV

Understanding the production mechanism of light (anti)nuclei is one of the key challenges of nuclear physics and has important consequences for astrophysics, since it provides an input for indirect dark-matter searches in space. In this paper, the latest results about the production of light (anti)nuclei in pp collisions at sqrt{s} = 13 TeV are presented, focusing on the comparison with the predictions of coalescence and thermal models. For the first time, the coalescence parameters B2 for deuterons and B3 for helions are compared with parameter-free theoretical predictions that are directly constrained by the femtoscopic measurement of the source radius in the same event class. A fair description of the data with a Gaussian wave function is observed for both deuteron and helion, supporting the coalescence mechanism for the production of light (anti)nuclei in pp collisions. This method paves the way for future investigations of the internal structure of more complex nuclear clusters, including the hypertriton.

Collision centrality and system size dependences of light nuclei production via dynamical coalescence mechanism

Light (anti-)nuclei in relativistic heavy-ion collisions are considered to be formed by the coalescence mechanism of (anti-)nucleons in the present work. Using a dynamical phase-space coalescence model coupled with a multi-phase transport (AMPT) model, we explore the formation of light clusters such as deuteron, triton and their anti-particles in different centralities for $^{197}$Au + $^{197}$Au collisions at $\sqrt{s_{NN}} = 39$ GeV. The calculated transverse momentum spectra of protons, deuterons, and tritons are comparable to those of experimental data from the RHIC-STAR collaboration. Both coalescence parameters $B_{2}$ for (anti-)deuteron and $B_{3}$ for triton increase with the transverse momentum as well as the collision centrality, and they are comparable with the measured values in experiments. The effect of system size on the production of light nuclei is also investigated by $^{10}$B + $^{10}$B, $^{16}$O + $^{16}$O, $^{40}$Ca + $^{40}$Ca, and $^{197}$Au + $^{197}$Au systems in central collisions. The results show that yields of light nuclei increase with system size, while the values of coalescence parameters present an opposite trend. It is interesting to see that the system size, as well as the centrality dependence of $B_A$ ($A$ = 2, 3), falls into the same group, which further demonstrates production probability of light nuclei is proportional to the size of the fireball. Furthermore, we compare our coalescence results with other models, such as the thermal model and analytic coalescence model, it seems that the description of light nuclei production is consistent with each other.

Modeling (anti)deuteron formation at RHIC with a geometric coalescence model

We study (anti)deuteron formation rates in heavy-ion collisions in the framework of a wave-function based coalescence model. The main feature of our model is that nucleons are emitted from the whole spherically symmetric fireball volume, while antinucleons are emitted only from a spherical shell close to the surface. In this way, the model accounts for nucleon-antinucleon annihilations in the center of the reaction at lower beam energies. Comparison with experimental data on the coalescence parameter in the range allows us to extract radii of the respective source geometries. Our results are qualitatively supported by data from the UrQMD transport model which shows a comparable trend in the geometric radii as a function of beam energy. In line with our expectations, we find that at lower energies, the central region of the fireball experiences stronger annihilation than at higher energies.

Waveguides with Exceptional Points of Degeneracy of Order 2, 3, 4 and 6 without Loss and Gain

We show various examples of fully-planar two-way and three-way microstrip coupled waveguides that exhibit second, third, fourth and sixth order exceptional points of degeneracy (EPD). EPDs are shown in reciprocal waveguides that do not have gain or loss. The occurrence of EPDs is observed using three methods: (i) the mathematical description of modes and the similarity of the system matrix to a Jordan block; (ii) the dispersion diagram with prescribed flatness; (iii) the coalescence of eigenvectors that is observed analytically or experimentally. We have defined a coalescence parameter that is used in conjunction with experimental results to measure the separation of the coalescing eigenvectors (polarization states). The presented structures can serve various applications like leaky-wave antennas, distributed amplifiers, oscillators, delay lines, pulse generators, and sensors.

Proton correlations and apparent intermittency in the UrQMD model with hadronic potentials

It is shown that the inclusion of hadronic interactions, and in particular nuclear potentials, in simulations of heavy ion collisions at the SPS energy range can lead to obvious correlations of protons. These correlations contribute significantly to an intermittency analysis as performed at the NA61 experiment. The beam energy and system size dependence is studied by comparing the resulting intermittency index for heavy ion collisions of different nuclei at beam energies of 40A, 80A and 150A GeV. The resulting intermittency index from our simulations is similar to the reported values of the NA61 collaboration, if nuclear interactions are included. The observed apparent intermittency signal is the result of the correlated proton pairs with small relative transverse momentum Δpt, which would be enhanced by hadronic potentials, and this correlation between the protons is slightly influenced by the coalescence parameters and the relative invariant four-momentum qinv cut.

Deuteron production in AuAu collisions at sNN=7–200 GeV via pion catalysis

We study deuteron production using no-coalescence hydrodynamic + transport simulations of central AuAu collisions at $\sqrt{s_{NN}} = 7 - 200$ GeV. Deuterons are sampled thermally at the transition from hydrodynamics to transport, and interact in transport dominantly via $\pi p n \leftrightarrow \pi d$ reactions. The measured proton, Lambda, and deuteron transverse momentum spectra and yields are reproduced well for all collision energies considered. We further provide a possible explanation for the measured minimum in the energy dependence of the coalescence parameter, $B_2(\sqrt{s_{NN}})$ as well as for the difference between $B_2(d)$ for deuterons and that for anti-deuterons, $B_2(\bar{d})$.