Search

High-mass stars are thought to accumulate much of their mass via short, infrequent bursts of disk-aided accretion. Such accretion events are rare and difficult to observe directly but are known to drive enhanced maser emission. In this Letter we report high-resolution, multi-epoch methanol maser observations toward G358.93-0.03 which reveal an interesting phenomenon; the sub-luminal propagation of a thermal radiation "heat-wave" emanating from an accreting high-mass proto-star. The extreme transformation of the maser emission implies a sudden intensification of thermal infrared radiation from within the inner (40 mas, 270 au) region. Subsequently, methanol masers trace the radial passage of thermal radiation through the environment at $\geq$ 4-8\% the speed of light. Such a high translocation rate contrasts with the $\leq$ 10 km s$^{-1}$ physical gas motions of methanol masers typically observed using very long baseline interferometry (VLBI). The observed scenario can readily be attributed to an accretion event in the high-mass proto-star G358.93-0.03-MM1. While being the third case in its class, G358.93-0.03-MM1 exhibits unique attributes hinting at a possible `zoo' of accretion burst types. These results promote the advantages of maser observations in understanding high-mass star formation, both through single-dish maser monitoring campaigns and via their international cooperation as VLBI arrays., Comment: Published in Nature Astronomy in 2020

On 16th October 2017 ex-hurricane Ophelia passed over the UK, bringing with it a unique mixture of particulates which caused the sky to turn a dramatic red colour. Here we use an ensemble of modelling and remote sensing techniques in a ‘top-down, bottom-up’ approach comprising instruments onboard orbital platforms and a ground-based lidar, to interrogate the particle loading to determine its composition and origins. Using a novel, miniature lidar system and back-trajectory modelling to link the measurements to sources, we show that the event comprised two distinct phases, the first dominated by Saharan dust (volume depolarisation ratio at 532 nm; δ = 0.15–0.25) and the second by an optically dense layer, starting at ∼0.7 km, comprising a mixture of Saharan dust and biomass burning particles (δ = 0.08–0.18) originating from intense wildfires in the Iberian Peninsula. CO levels in the weather system were measured as high as ∼273 ppbV and the aerosol index to be >5. Also, the Ophelia system was probed for the first time using multi-spectral imaging data from the Multispectral Instrument (MSI) onboard Sentinel-2. This allowed the differentiation of cloud composition types from above by virtue of the different spectral signatures of the components of the cloud matrix and in doing so gave important supporting evidence to complement the ground-based lidar observations.

An avalanche dynamic model is proposed for the three-dimensional simulation of avalanche dynamics that adopts the Navier–Stokes equations as the governing framework and introduces μ(I) granular rheology in the constitutive law. Using the finite–volume method as the numerical scheme, a simulation program based on the OpenFOAM open-source platform was developed. The validity of the model as well as the program was verified by numerical simulations of a laboratory-scale granular flow test. An interface developed between the natural terrain data and the calculation program enables the simulation of natural avalanches. The Baige avalanche, a natural event, was reproduced. Comparisons between simulations and real data further verify the feasibility and accuracy of the full avalanche dynamic model. In addition, the evolution of the hydrostatic pressure, shear strain rate, inertial number, and kinematic viscosity over the duration of the avalanche were analyzed to extract the underlying internal mechanism.

The measurement of the mass composition of ultra-high energy cosmic rays constitutes a prime challenge in astroparticle physics. Most detailed information on the composition can be obtained from measurements of the depth of maximum of air showers, $X_{\mathrm{max}}$, with the use of fluorescence telescopes, which can be operated only during clear and moonless nights. Using deep neural networks, it is now possible for the first time to perform an event-by-event reconstruction of $X_{\mathrm{max}}$ with the Surface Detector (SD) of the Pierre Auger Observatory. Therefore, previously recorded data can be analyzed for information on $X_{\mathrm{max}}$, and thus, the cosmic-ray composition. Since the SD operates with a duty cycle of almost $100\%$ and its event selection is less strict than for the Fluorescence Detector (FD), the gain in statistics with respect to the FD is almost a factor of 15 for energies above $10^{19.5}~\mathrm{eV}$. In this contribution, we introduce the neural network particularly designed for the SD of the Pierre Auger Observatory. We evaluate its performance using three different hadronic interaction models, verify its functionality using Auger hybrid measurements, and find that the method can extract mass information on an event level.

Hadronic resonances play an important role in the study of the physics of heavy-ion collisions. In these proceedings, we discuss how the resonances can probe the reaction dynamics, the strangeness production and the properties of the hadronic phase in heavy-ion collisions at center-of-mass energies of sNN = 4–11 GeV. The resonance properties predicted by the general-purpose event generators are found to be very sensitive to the properties and space-time evolution of the medium produced in heavy-ion collisions.

Diverse studies about equatorial plasma bubble structures and their relation with ionospheric scintillation have been performed in the last decades. Among many findings, the investigations usually reported dominant plasma bubble eastward velocity with a magnitude of few tens of m/s and larger amplitude scintillation for transionospheric signals aligned with these depleted structures. However, an uncommon long-lasting event with negligible average zonal drift prevailing for hundreds of minutes was registered over the Brazilian region, allowing a case study of the scintillation pattern under this particular condition. Data from ionosondes, all-sky imager (6300 A filter), geostationary satellites and Global Navigation Satellite System were used here, covering the eastern portion of the Brazilian ionosphere. The results show that the scintillation was less intense than in other nights around the event, suggesting that larger plasma density gradients and sequential bubble structures seem to cause more severe scintillation scenario than the alignment condition alone, even though the last also contributes to worsen the scintillation effects. Regarding the stagnant bubble pattern, the results suggest prevailing E region Hall conductivity and equatorward wind as potential agents.

The Earth’s accretion process is accompanied by a large number of collisions. It is widely accepted that collisions dominate the Earth’s late accretion stage. Among all these collisions, there is a special type of collision called Core-merging giant impact (CMGI), in which much or most the impactor’s core merges directly with the proto-Earth’s core. This core-merging scenario plays an important role in the Earth’s accretion process and deeply affects the formation of the Earth’s core and mantle. However, because CMGI is a small probability event, it has not been fully studied. Here we use the SPH method to comprehensively study all possible CMGIs in the Earth’s accretion history. We find that CMGI only occurs in the initial conditions with small impact angle, small impact velocity and big impactor. We further discuss the implications of CMGI. We are confident that CMGI inevitably causes the chemical disequilibrium of the Earth's core and mantle. The CMGI process also brings many light elements into the Earth’s core. In particular, if the Moon-forming giant impact is a CMGI, then CMGI can also explain the abnormal content of HSEs in the Earth’s current mantle.

In downhole microseismic monitoring, the velocity model plays a vital role in accurate mapping of the hydraulic fracturing image. For velocity model uncertainties in the number of layers or interface depths, the conventional velocity calibration method has been shown to effectively locate the perforation shots; however, it introduces nonnegligible location errors for microseismic events, especially for complex geologic formations with inclinations. To improve the event location accuracy, we have exploited the advantages of the reversible jump Markov chain Monte Carlo approach in generating different dimensions of velocity models and adopted a transdimensional Bayesian simultaneous inversion framework for obtaining the effective velocity structure and event locations simultaneously. The transdimensional inversion changes the number of layers during the inversion process and selects the optimal interface depths and velocity values to improve the event location accuracy. The confidence intervals of the simultaneous inversion event locations estimated by Bayesian inference enable us to evaluate the location uncertainties in the horizontal and vertical directions. Two synthetic examples and a field test are presented to illustrate the performance of our methodology, and the event location accuracy is shown to be higher than that obtained using the conventional methods. With less dependence on prior information, our transdimensional simultaneous inversion method can be used to obtain an effective velocity structure for facilitating highly accurate hydraulic fracturing mapping.

With the advent of the High-Luminosity Large Hadron Collider (HL-LHC) era, high energy physics (HEP) event selection will require new approaches to rapidly and accurately analyze vast databases. The current study addresses the enormity of HEP databases in an unprecedented manner—a quantum search using Grover’s Algorithm (GA) on an unsorted database, ATLAS Open Data, from the ATLAS detector. A novel method to identify rare events at 13 TeV in CERN’s LHC using quantum computing (QC) is presented. As indicated by the Higgs boson decay channel $$H\rightarrow ZZ^*\rightarrow 4l$$ H → Z Z ∗ → 4 l , the detection of four leptons in one event may be used to reconstruct the Higgs boson and, more importantly, evince Higgs boson decay to some new phenomena, such as $$H\rightarrow ZZ_d \rightarrow 4l$$ H → Z Z d → 4 l . Searching the dataset for collisions resulting in detection of four leptons using a Jupyter Notebook, a classical simulation of GA, and several quantum computers with multiple qubits, the current application was found to make the proper selection in the unsorted dataset. Quantum search efficacy was analyzed for the incoming HL-LHC by implementing the QC method on multiple classical simulators and IBM’s quantum computers with the IBM Qiskit Open Source Software. The current QC application provides a novel, high-efficiency alternative to classical database searches, demonstrating its potential utility as a rapid and increasingly accurate search method in HEP.

Using hydrodynamical $N$-body simulations, we show that the observed structure and kinematics of the extremely metal-poor, dwarf irregular galaxy DDO 68 is compatible with a merger event with at least two smaller satellite galaxies. We were able to obtain a self-consistent model that simultaneously reproduces several of its observed features, including: the very asymmetric and disturbed shape of the stellar component, the overall HI distribution and its velocity field, the arc-like stellar structure to the west, the low-surface brightness stellar stream to the north. The model implies the interaction of the main progenitor of DDO 68 with two systems with dynamical masses $7\times10^8\,M_{\odot}$ and almost $10^8\,M_{\odot}$ -- 1/20 and 1/150 times the dynamical mass of DDO 68, respectively. We show that the merger between DDO 68 and the most massive of its satellites offers a route to explain the large offset of DDO 68 from the mass-metallicity relation. Assuming that the interacting galaxies have metallicities prior to the merger compatible with those of galaxies with similar stellar masses, we provide quantitative evidence that gas mixing alone does not suffice at diluting the gas of the two components; according to our simulations, the HII regions observed along the Cometary Tail trace the low metallicity of the accreted satellite rather than that of DDO 68's main body. In this case, the mass corresponding to the low metallicity is that of the secondary body and DDO 68 becomes consistent with the mass-metallicity relation., Accepted for publication in MNRAS. 17 pages, 10 figures

The supercharged nature of the Earth’s geothermal core can be demonstrated by three thought experiments exhibiting it is tremendously more powerful than any other terrestrial object in the solar system (planet or moon). Identifying a minimum of four byproduct asteroid blast patterns linked to the formation of Earth’s supercharged geothermal core is critical to properly identifying stars that also have these four byproduct asteroid blast patterns. These stars are the most likely to host an Earth-like planet qualified by having a supercharged geothermal core. The Planetary Vaporization-Event (PVE) Hypothesis provides a basis for correlation between the supercharged nature of Earth’s geothermal core and at least 14 listed side effects: (1) the asteroid-wide/planet-scale homogenization and lack thereof of 182W ε for Earth, the Moon, Mars and meteors, (2) the primary and secondary shifting of Earth’s tectonic plates, (3) the solar system wide displacement of Earth’s wayward moons (including Ceres, Pluto, Charon and Orcus) outgassing identical samples of ammoniated phyllosilicates, (4) the formation of asteroids at 100+ times the expected density of a nebular cloud vs. pre-solar grains formation density at the expected density of a nebular cloud, (5) three distinct formation timestamps for all known asteroids within a 5 million year window 4.55+ billion years ago, (6) the estimated formation temperature of CAI at 0.86 billion Kelvin and (7) the remaining chondritic meteorite matrix flash vaporizing at 1,200–1,900 °C, (8) followed by rapid freezing near 0 K, (9) the development of exactly 2 asteroid belts and a swarm of non-moon satellites, (10) particulate size distinction between the 2 asteroid belts of small/inner, large/outer, (11) the proximity of the Trojan Asteroid Groups to the Main Asteroid Belt, (12) observation of a past or present LHB, (13) the development of annual meteor showers for Earth proximal to apogee and/or perigee, (14) the Sun being the most-likely object struck by an asteroid in the inner solar system. Through better understanding of the relevant data at hand and reclassification of the byproducts of supercharging the core of a planet, at least 5 new insights can be inferred and are listed as: (1) the original mass, (2) distance and (3) speed of Earth Mark One, (4) the original order of Earth’s multi-moon formation and (5) the high probability of finding detectable signs of life on a planet orbiting the stars Epsilon Eridani and Eta Corvi. There are at least 6 popular hypothesis that the PVE Hypothesis is in conflict with, listed they are: (1) a giant impact forming the Moon, (2) asteroids being the building blocks of the solar system, (3) the Main Asteroid Belt being the result of a planet that never formed, (4) the LHB being a part of the accretion disk process, (5) the heat in Earth’s core coming primarily from the decay of radioactive elements, (6) the Oort Cloud being the source of ice comets.

Ice multiplication by fragmentation during collision–freezing of supercooled rain or drizzle is investigated. A zero-dimensional dynamical system describes the time evolution of number densities of supercooled drops and ice crystals in a mixed-phase cloud. The characteristic time scale for this collision–freezing ice fragmentation is controlled by the collision efficiency, the number of ice fragments per freezing event, and the available number concentration of supercooled drops. The rate of the process is proportional to the number of supercooled drops available. Thus, ice may multiply extensively, even when the fragmentation number per freezing event is relatively small. The ratio of total numbers of ice particles to those from the first ice, namely, the “ice-enhancement factor,” is controlled both by the number of fragments per freezing event and by the available number concentration of supercooled drops in a similar manner. Especially, when ice fragmentation by freezing of supercooled drops is considered in isolation, the number of originally existing supercooled drops multiplied by the fragmentation number per freezing event yields the eventual number of ice crystals. When supercooled drops are continuously generated by coalescence, ice crystals from freezing fragmentation also continuously increase asymptotically at a rate equal to the generation rate of supercooled drops multiplied by the fragmentation number per freezing event. All these results are expressed by simple analytical forms, thanks to the simplicity of the theoretical model. These parameters can practically be used as a means for characterizing observed mixed-phase clouds.

A statistical study of interplanetary disturbances with different positions of the interplanetary magnetic field maximum that generate Forbush decreases is performed. It is shown that the most effective interplanetary disturbances are those with the position of the field maximum 6–15 h after the start of the event.

This paper reports on the design, construction, and operation of a 1 kg C3F8 bubble chamber intended for applications such as space missions for measurement and monitoring of galactic cosmic rays. The event signal analysis aims towards a full discrimination from known particles (neutrons and alphas). With the use of a hydrophone, a 95% efficiency signal detection was achieved. Test calibrations indicate an overlap of the two power distributions and 74% of well-discriminated events. Pressure signal differences also conjecture on the nature of the event signals. This work shows the performance of a bubble chamber that allows high-pressure (16 bar) operations. The increase in operational recompression leads to a reduction of the detector's dead time by a factor of six.

—The effects of the strong natural events on the acoustic fields in the atmosphere, geomagnetic field, and electrical characteristics of atmospheric surface layer—atmospheric current and electric field—are discussed. The extreme events analyzed in the paper are volcanic eruptions, earthquakes, and impacts of outer space bodies falling to the Earth. These natural phenomena are considered as local indicators of the enhancement of interactions between the geospheres in the lithosphere–atmosphere near-surface system with active involvement of the ionosphere. It is shown that in these cases, the induced effects in the geophysical fields are observed at quite a distance from an event source and have similar amplitudes, probably suggesting a special role of the ionosphere in a rapid long-distance transfer of the disturbances. The effect of the acoustic-gravity waves generated by the strong natural events in their epicentral zone is considered as the main excitation mechanism of the ionosphere. The objectives and tasks of the research aimed at establishing the main regularities and interaction mechanisms between the geospheres in the environment are formulated.

A new method is proposed for improving the IRI2016 vertical electron density profile by ingesting the in situ Ne values from Swarm A, B and C. The method is validated by comparing the improved electron density profiles with measured full height profiles over three Incoherent Scatter Radar stations in the American sector (Jicamarca, Millstone Hill and Sondrestrom) during the period 5–11 September 2017 covering both quiet and storm days. We considered 90 epochs corresponding to times when one of the Swarm satellites passed near an Incoherent Scatter Radar at a time when the Incoherent Scatter Radar was measuring electron density profiles. The method results in improvements of the electron density profile, as measured in terms of the Root-Mean-Square-Error in 63% of the observed epochs. The fraction of improvements on quiet days is 63% of the observed epochs, while 37% of the improvements occurred on storm days. The change in Root-Mean-Square-Error of the IRI profile compared to the ISR profiles before and after the modification was not dependent on the distance between the observation location and the ISR, nor on the difference between the hmF2 predicted by the IRI and measured by the ISR.

We present the results of the analysis of the observational data for the eruptive event of June 7, 2011 obtained both on spacecraft (SDO, LASCO) and using ground-based solar instruments. The event was characterized by deceleration of the shock front during the first minutes of the evolution from 1150 to 710 km/s. According to the LASCO data, the velocity of the coronal mass ejection (CME) on time scales of more than an hour did not exceed 285 km/s. According to the spectral observations of the ground-based instrument, we found the radial velocities of the fastest features of the exploding prominence to be between 200 and 190 km/s. We paid special attention to studying the physical characteristics of a blob—a separate drop of coronal rain that accompanied the event. The line-of-sight velocity of the blob increased in 5 min from 207 to 263 km/s, its diameter was 5900 km, and the estimated mass was 1.8 × 1012 g; the values of temperature and turbulent velocity of 7880 K and Vturb = 18.7 km/s were obtained,correspondingly. We should note that the finding and measurement of velocities were limited by the capabilities of narrow-band filters and a small wavelength range in most solar instruments. This paper is based on the report made at the conference “Ideas of S.B. Pikelner and S.A. Kaplan and Modern Astrophysics” (Sternberg Astronomical Institute, Moscow State University, February 8–12, 2021).

Anomalies among the daughter nuclei of the extinct short-lived radionuclides (SLRs) in the calcium-aluminum-rich inclusions (CAIs) indicate that the Solar System must have been born near a source of the SLRs so that they could be incorporated before they decayed away. $\gamma$-rays from one such living SLR, $^{26}$Al, are detected in only a few nearby star-forming regions. Here we employ multi-wavelength observations to demonstrate that one such region, Ophiuchus, containing many pre-stellar cores that may serve as analogs for the emerging Solar System, is inundated with $^{26}$Al from the neighboring Upper-Scorpius association, and so may provide concrete guidance for how SLR enrichment proceeded in the Solar System complementary to the meteoritics. We demonstrate via Bayesian forward modeling drawing on a wide range of observational and theoretical results that this $^{26}$Al likely 1) arises from supernova explosions, 2) arises from multiple stars, 3) has enriched the gas prior to the formation of the cores, and 4) gives rise to a broad distribution of core enrichment spanning about two orders of magnitude. This means that if the spread in CAI ages is small, as it is in the Solar System, protoplanetary disks must suffer a global heating event., Comment: Published in Nature Astronomy, August 16, 2021

The recent observations of gravitational waves during the coalescence of black holes has confirmed various predictions of general relativity. However, some concerns have been raised that these putative waves are artifacts. We have analyzed the ten confident gravitational waves detected in Observation Run 1 (O1) and Observation Run 2 (O2) and the gravitational wave emitted by the single known example of a neutron star coalescence, all of which have been verified by the Advanced Laser Interferometer Gravitational Wave Observatory and/or the Advanced Virgo Collaboration. On three occasions both Advanced LIGO and Advanced Virgo detected the same event ( Abbott et al., 2019 ). Whitening of the Hanford data (Gravitational Wave Open Science Center) was employed in this study to reduce colored non-transient noise, but template matching was not employed. In each of the ten events mentioned above we verified the presence of such waves by the application of non-stationary data analysis via the Morlet wavelet. We examined the strain data before, during and after each wave. In each case we employed seven measures of complexity or information before, and during each wave and analyzed these data using doubly multivariate MANOVA, the appropriate statistical test for repeated measures (pre-wave vs wave). In addition we compared the strain data before and after the putative event to see if there was persistence of any effect of the event. In each case the information content was significantly elevated during the wave compared to similar time samples taken before the wave. No persistent effects on the strain data were noted after the event. We conclude our analysis is consistent with the actual detection of gravitational waves by the LIGO and Virgo Collaboration. Our results suggest black hole coalescence generates mathematically complex gravitational waves which may elucidate aspects of such coalescence.

We present a study of collective effects and dynamics of quark-hadron phase transitions by means of the femtoscopic correlations of hadrons at the NICA energies. A set of simulations of heavy-ion collisions (AuAu, BiBi) at the energies to be available with the NICA collider and experiments to be operated there (in particular, the MPD experiment), has been performed using two Monte Carlo generators. A femtoscopic analysis for charged pions and kaons have shown a sensitivity of the observables to the equation of state (EoS) for both event generators. Also, a study of the influence of detector effects like track-merging and track-splitting in the TPC, the main tracker device of the MPD experiment, on femtoscopic measurements is presented in this work.

The multipurpose detector (MPD) is designed as a 4 $$\pi $$ -spectrometer capable of detecting charged hadrons in the energy range of the NICA collider. The main physics goals of NICA and the concept of the MPD detector are presented with an emphasis on detector performance in the measurements of high-order moments of net-proton and net-kaon multiplicity distributions.

Over the hours of 05:00–09:00 UT on 8 June 2001, the extreme ultraviolet (EUV) instrument on board the IMAGE satellite observed a shoulder-like formation in the morning sector and a post-noon plume-like structure. The plasmapause formation is simulated using the test particle model (TPM), based on a drift motion theory, which reproduces various plasmapause structures and evolution of the shoulder feature. The analysis indicates that the shoulder is created by sharp reduction and spatial non-uniformity in the dawn–dusk convection electric field intensity. The TPM-modeled event is found to develop an initial pre-dawn asymmetric bulge that becomes a shoulder as a result of increased “corotation” rate with an increasing L-shell that is preceded by localized outward convection. The shoulder structure rotates sunward and develops into a single- or double-plume structure during an active time period in simulation.

The multi-purpose detector (MPD) is the flagship experiment at NICA (Nuclotron-based Ion Collider fAcility) which is currently under construction at the Joint Institute for Nuclear Research. It is realized in the frame of a large international scientific collaboration. In this work, the status of the preparation of the subdetector components is briefly summarized. The assembly of the solenoidal magnet composed of superconducting coil and iron yoke will be followed by the installation of main subdetectors: time projection chamber, time of flight, electromagnetic calorimeter, fast forward detector and forward hadronic calorimeter. Preparations for the software and computing infrastructure are described. An overview of the MPD physics programme is also given, with emphasis on overall event characteristics and bulk observables, such as single particle spectra, particle identification and basic correlation measurements, as well as dedicated studies of electromagnetic probes and heavy flavor.

The production cross section of vector bosons recoiling against jets is studied, with CMS data, differentially as a function of the transverse momentum and angular correlations of the final state particles. The measurements are confronted with different state-of-the-art theory predictions that include next-to-leading-order calculations and matrix-element plus parton shower event simulations.

Soft-drop grooming of hadron-collision final states has the potential to significantly reduce the impact of non-perturbative corrections, and in particular the underlying-event contribution. This eventually will enable a more direct comparison of accurate perturbative predictions with experimental measurements. In this study we consider soft-drop groomed dijet event shapes. We derive general results needed to perform the resummation of suitable event-shape variables to next-to-leading logarithmic (NLL) accuracy matched to exact next-to-leading order (NLO) QCD matrix elements. We compile predictions for the transverse-thrust shape accurate to NLO+NLL' using the implementation of the CAESAR formalism in the Sherpa event generator framework. We complement this by state-of-the-art parton- and hadron-level predictions based on NLO QCD matrix elements matched with parton showers. We explore the potential to mitigate non-perturbative corrections for particle-level and track-based measurements of transverse thrust by considering a wide range of soft-drop parameters. We find that soft-drop grooming indeed is very efficient in removing the underlying event. This motivates future experimental measurements to be compared to precise QCD predictions and employed to constrain non-perturbative models in Monte-Carlo simulations., 50 pages, 21 figures, extended discussion, version accepted for publication in JHEP

The anisotropic collective flow is one of the important observables sensitive to the transport properties of strongly interacting matter created in relativistic heavy-ion collisions. The performance of the multi-purpose detector (MPD) at NICA collider for elliptic flow measurements of identified charged pions, protons, $$K_{s}^{0}$$ and $$\Lambda $$ particles is studied with Monte Carlo simulations using collisions of Au + Au ions employing the UrQMD event generator. Different methods for flow measurements: event plane and direct cumulants are used to investigate the contribution of non-flow correlations and flow fluctuations.

The particle based Discrete Element Method (DEM) can be applied to examine comminution processes. In this study, a DEM framework has been extended to model particle breakage without mass loss. After a breakage event occurs, spherical particles, as often considered in the DEM, are replaced by size reduced spherical fragments. During the following time steps, the fragments grow to their desired sizes, so that the mass loss can be counterbalanced. Previously defined overlaps with adjacent unbroken and broken particles (fragments) as well as walls are allowed. The breakage model has been realized in a parallelized DEM framework because comminution processes are often attributed to large numbers of particles and by parallelization the computational time can be reduced efficiently. An oedometer (one-dimensional compression in axial direction of a confined particle bed) has been modelled to investigate the parallelization efficiency and the influence of the permitted overlaps during the growth process on the growth duration. A simplified roller mill has been considered to examine the applicability of the breakage procedure considering parallelization. The results show that parallelization reduces computational time considerably. The breakage procedure is suitable to model comminution processes involving even densely packed particle systems and is superior to existing approaches.

One of the actual tasks in the analysis of already collected data at the BM@N experiment is a classification of events according to their centrality using the energy of projectile spectators measured with the ZDC. The experimental problems and proposed approaches to determine event centrality are discussed. A new approach, based on machine learning techniques, for centrality determination with a new FHCal in future heavy ion experiments is proposed and simulation results are shown for Au + Au collision of 4.5 AGeV. The FHCal calibration procedure with cosmic muons as well as its preliminary results are presented.

We present a method to constrain the temperature of astrophysical black holes through detecting the inspiral phase of binary black hole coalescences. At sufficient separation, inspiraling black holes can be regarded as isolated objects, hence their temperature can still be defined. Due to their intrinsic radiation, inspiraling black holes lose part of their masses during the inspiral phase. As a result, coalescence speeds up, introducing a correction to the orbital phase. We show that this dephasing may allow us to constrain the temperature of inspiraling black holes through gravitational-wave detection. Using the binary black-hole coalescences of the first two observing runs of the Advanced LIGO and Virgo detectors, we constrain the temperature of parental black holes to be less than about $ 10^9 $ K. Such a constraint corresponds to luminosity of about $ 10^{-16} M_{\odot} \rm s^{-1} $ for a black hole of $ 20 M_{\odot} $, which is about 20 orders of magnitude below the peak luminosity of the corresponding gravitational-wave event, indicating no evidence for strong quantum-gravity effects through the detection of the inspiral phase., Comment: Match the published version

On the basis of scientific provisions of statistical mechanics and the entropy method arising from these provisions, the article substantiates the physical and mathematical modeling of the kinetics of the process of loose material mixing in a mixing installation, while the blade of the machine is simulated by an absorbing wall. Using the resulting solution to the task on the counting density of weight particle distribution near the blade (as the probability of this event), an equation for calculating the mixing factor (a parameter of mixture quality) is derived. A method for calculating the basic control parameter of the mixing process (the macro-diffusion factor) independent of the process parameters of the blade installation is proposed. On the basis of experiments on mixing portions of loose materials, the adequacy of the results of calculating the kinetics of the process of mixing portions of the product according to the developed algorithm has been confirmed.

We estimate the yields of particles at central rapidities and large transverse momenta in the region outside NN-kinematics (the so-called cumulative region) in AuAu collisions. We suppose that particles in this kinematical region are produced by scattering from the clusters of cold dense quark–gluon matter present inside nuclei—the nuclear “fluctons”. We found that in this new cumulative region the yields of pions compared to the yields of protons will be less suppressed at the same value of the cumulative number, in contrast with the situation in a traditional cumulative region of nucleus fragmentation. This effect is caused by a stronger decrease of the cumulative proton yield with transverse momentum compared to pions. That could be evidence of the different formation mechanisms of these cumulative particles—the coherent coalescence (recombination) of three flucton quarks for a proton and the fragmentation of one flucton quark for a pion. We also discuss the need to use the future internal vertex tracker of MPD at NICA for the suppression of the contribution from the event pile-up when registering the particles formed from fragmentation of the flucton residue.

We perform a geomagnetic event simulation using a newly developed magnetohydrodynamic with adaptively embedded particle-in-cell (MHD-AEPIC) model to study by solving the magnetotail reconnection ph...

The ramifications of gust-front on atmospheric surface layer (ASL) turbulence is a vexing issue, with nearly no information available over the Indian region where such events are not uncommon. Over the Indian peninsula, Chowdhuri et al. (Environ. Fluid Mech. 21(1):263–281, 2021) have shown that, the cold pool associated with the gust-front creates two distinct regimes in ASL turbulence, where the temperature fluctuations display contrasting behavior. To evaluate the corresponding impacts on the moisture fluctuations and turbulent heat and moisture transport, we extend our analysis by using the same field-experimental dataset of Chowdhuri et al. (2021). We discover that, the topology of the turbulent structures which govern the temperature and moisture fluctuations clearly exhibit a regime-wise distinction. In the first regime, the structures in temperature and moisture fluctuations are significantly inclined in the vertical, while demonstrating a self-similarity in their time scales by being related through a power-law distribution. However, in the second regime, the vertical inclination disappears for the temperature structures with hardly any change observed for the moisture. Moreover, the power-law exponents of the turbulent temperature time scales remain sensitive to the regimes, although no such effect is visible in the power-law character of the moisture time scales. Additionally, the dissimilarity in the heat and moisture transport is investigated through a novel polar-quadrant based approach that separates the phases and amplitudes of the flux-transporting motions.

A binary black hole (BH) astrophysical scenario where a mass-constrained (2.5 × 10−13M⊙) primordial black hole (PBH) undergoes a radial fall on to its heavier component (such as a supermassive black hole, SMBH) is described as an intense gamma-ray emission event. As the relativistic PBH approaches the Schwarschild SMBH event horizon, its Lorentz-boosted Hawking radiation progressively reduces to a near-zero emission cone resulting in a highly collimated thermal beam. Accordingly, our numerically calculated PBH flux density Sν and νSν fluence spectrum show a decreasing Planck-like spectral dependence consistent with the cooling behaviour of thermal-dominant gamma-ray bursts (GRBs). Our results might provide an alternative explanation for thermal GRBs based on PBH origin.

The presented work documents the results of a comprehensive sensitivity study of the structural response of a military vehicle subjected to the impulse from a buried charge using the discrete particle method (DPM) to model the soil and high explosive (HE) coupled to a finite-element solver for the structure. Eighteen different process and numerical parameters were studied. Each of the numerical results was compared with a base model to see the influence of the considered parameter. The structure in the base model was the TARDEC Generic Vehicle Hull and the response parameter was chosen to be the total blast impulse (TBI) on the structure. The non-linear transient dynamic explicit finite-element solver used for the analysis was the IMPETUS Afea Solver®. The study includes soil characteristics and charge related parameters, such as size, type, geometry, and location. The depth of burial (DOB) and number of discrete particles were also considered in the study. Further, different numerical parameters were included. The results provide a good understanding of process and numerical parameters when modeling buried charges with a coupled finite-element model (FEM) and DPM approach. As a natural extension of the sensitivity study the effect of a layered soil bed is investigated, the topsoil either being dry or wet soil. Further, it is illustrated how to model a sympathetic detonation where the detonation of one improvised explosive device (IED) generates a pressure that results in the detonation of a second IED.

During heavy-ion experiments, the single-event gate rupture (SEGR) effects can still be observed in the vertical double-diffused power MOSFET (VDMOS) with radiation-hardened cells. Fault analysis demonstrates that the hot spots locate at the termination of the VDMOS. Then, several mitigation solutions for termination structure are discussed comprehensively by means of TCAD simulations. Finally, a combined hardness method with horizontally extending P+ region and adding floating N+ region is proposed. It is effective to reduce the electric field of gate oxide to below the calculated critical field, without additional masks and process steps.

The influence of ion track characteristics on single-event upsets (SEU) and multiple-cell upsets (MCUs) is investigated in 65-nm static randon access memory (SRAM) above the heavy-ion linear energy transfer (LET) threshold. The experimental results show that for the incident heavy ions with the same or similar LET but different energies, SEU cross section of low-energy ions is higher than high-energy ions when the LET values are located below the knee point of low-energy SEU event cross section curves. With the LET values increasing above the knee point, SEU cross section of high-energy ions is higher than low-energy ions. When the effective LETs of different-energy ions within the sensitive region are the same, MCU mean, MCU ratio, and MCU event cross sections of high-energy ions are greater than those of low-energy ions due to larger track radius. During the test evaluation of heavy-ion single-event effect (SEE) in nanometer devices, it may be advisable that the SEU LET threshold be obtained with low-energy ions and the SEU saturation cross section be obtained with high-energy ions.

The distribution of single-event upsets (SEUs) in commercial off-the-shelf (COTS) static random access memory (SRAM) has generally been thought to be uniform in a device. However, process-induced variation within a device gives rise to variation within the cell-level electrical characteristic known as the data retention voltage ( $V_{\mathrm{ DR}}$ ). Furthermore, $V_{\mathrm{ DR}}$ has been shown to directly influence the critical charge ( $Q_{\mathrm{ C}}$ ) necessary for stored data to upset. Low-energy proton irradiation of COTS SRAMs exhibits a preference toward upsetting cells with lower $Q_{\mathrm{ C}}$ . An electrical procedure is presented to map relative cell critical charge values without knowledge of the underlying circuitry, allowing customized device usage. Given cell-level $Q_{\mathrm{ C}}$ knowledge, a device can have its cells “screened” such that those with low $Q_{\mathrm{ C}}$ are not used to store data. This work presents the results such a screening process has on the SEU per bit cross section.

We report the discovery of bright, fast, radio flashes lasting tens of seconds with the AARTFAAC high-cadence all-sky survey at 60 MHz. The vast majority of these coincide with known, bright radio sources that brighten by factors of up to 100 during such an event. We attribute them to magnification events induced by plasma near the Earth, most likely in the densest parts of the ionosphere. They can occur both in relative isolation, during otherwise quiescent ionospheric conditions, and in large clusters during more turbulent ionospheric conditions. Using a toy model, we show that the likely origin of the more extreme (up to a factor of 100 or so) magnification events likely originate in the region of peak electron density in the ionosphere, at an altitude of 300-400 km. Distinguishing these events from genuine astrophysical transients is imperative for future surveys searching for low frequency radio transient at timescales below a minute., 11 pages, 10 figures. Accepted by MNRAS

Atmospheric new particle formation (NPF) is a crucial process driving aerosol number concentrations in the atmosphere; it can significantly impact the evolution of atmospheric aerosol and cloud processes. This study analyses at least 1 year of asynchronous particle number size distributions from six different locations in India. We also analyze the frequency of NPF and its contribution to cloud condensation nuclei (CCN) concentrations. We found that the NPF frequency has a considerable seasonal variability. At the measurement sites analyzed in this study, NPF frequently occurs in March–May (pre-monsoon, about 21 % of the days) and is the least common in October–November (post-monsoon, about 7 % of the days). Considering the NPF events in all locations, the particle formation rate (JSDS) varied by more than 2 orders of magnitude (0.001–0.6 cm−3 s−1) and the growth rate between the smallest detectable size and 25 nm (GRSDS-25 nm) by about 3 orders of magnitude (0.2–17.2 nm h−1). We found that JSDS was higher by nearly 1 order of magnitude during NPF events in urban areas than mountain sites. GRSDS did not show a systematic difference. Our results showed that NPF events could significantly modulate the shape of particle number size distributions and CCN concentrations in India. The contribution of a given NPF event to CCN concentrations was the highest in urban locations (4.3 × 103 cm−3 per event and 1.2 × 103 cm−3 per event for 50 and 100 nm, respectively) as compared to mountain background sites (2.7 × 103 cm−3 per event and 1.0 × 103 cm−3 per event, respectively). We emphasize that the physical and chemical pathways responsible for NPF and factors that control its contribution to CCN production require in situ field observations using recent advances in aerosol and its precursor gaseous measurement techniques.

This paper presents a method of how to determine spatial angles of ionizing radiation incidence quickly, using a Timepix3 detector. This work focuses on the dosimetric applications where detectors and measured quantities show significant angle dependencies. A determined angle of incidence can be used to correct for the angle dependence of a planar Timepix3 detector. Up until now, only passive dosemeters have been able to provide a correct dose and preserve the corresponding incidence angle of the radiation. Unfortunately, passive dosemeters cannot provide this information in “real” time. In our special setup we were able to retrieve the spatial angles with a runtime of less than 600 ms. Employing the new Timepix3 detector enables the use of effective data analysis where the direction of incident radiation is computed from a simple photon event map. In order to obtain this angle, we combine the information extracted from the map with known 3D geometry surrounding the detector. Moreover, we analyze the computation time behavior, conditions and optimizations of the developed spatial angle calculation algorithm.

Transverse momentum distributions of deuterons and antideuterons in Au + Au collisions at s NN = 14.5 , 62.4, and 200 GeV with different centrality are studied in the framework of the multisource thermal model. Transverse momentum spectra are conformably and approximately described by the Tsallis distribution. The dependence of parameters (average transverse momenta, effective temperature, and entropy index) on event centrality is obtained. It is found that the parameters T increase and q decrease with increase of the average number of particles involved in collisions, which reveals the transverse excitation degree increases with collision centrality.

The radiation effects in electronic parts are called single-event effects, which are deemed to be critical for space missions. This paper presents the Single Event Upsets that were observed in an onboard memory device of the Low Earth Orbit “Flying Laptop” satellite mission during its in-orbit operation. The Single Event Upsets were carefully mapped on the satellite orbital space itself and their root causes were investigated together with their rates of occurrence. Subsequently, the events were traced to show several root cause sources such as (i) trapped energetic protons leaking to low altitudes within the South Atlantic Anomaly, (ii) Solar Energetic Particles emitted by an impulsive event on 10 September 2017, and (iii) Galactic Cosmic Rays. A profound analysis was carried out on the observed flight data, and its corresponding results are actually in agreement with the standard energetic particle models. The presented results provide another important insight on the Single Event Upsets for future Low Earth Orbit satellite missions.

In 1927, at the Solvay conference, Einstein posed a thought experiment with the primary intention of showing the incompleteness of quantum mechanics; to prove it, he employed the instantaneous nonlocal effects caused by the collapse of the wavefunction of a single particle—the spooky action at a distance–, when a measurement is done. This historical event preceded the well-know Einstein–Podolsk–Rosen criticism over the incompleteness of quantum mechanics. Here, by using the Stern–Gerlach experiment, we demonstrate how the instantaneous nonlocal feature of the collapse of the wavefunction together with the single-particle entanglement can be used to produce the nonlocal effect of steering, i.e. the single-particle steering. In the steering process Bob gets a quantum state depending on which observable Alice decides to measure. To accomplish this, we fully exploit the spreading (over large distances) of the entangled wavefunction of the single-particle. In particular, we demonstrate that the nonlocality of the single-particle entangled state allows the particle to “know” about the kind of detector Alice is using to steer Bob’s state. Therefore, notwithstanding strong counterarguments, we prove that the single-particle entanglement gives rise to truly nonlocal effects at two faraway places. This opens the possibility of using the single-particle entanglement for implementing truly nonlocal task.

Recent observations of QGP-like conditions in high-multiplicity pp collisions from ALICE experiment at the LHC warrant an introspection whether to use pp collisions as a baseline measurement to characterize heavy-ion collisions for the possible formation of a Quark-Gluon Plasma. A double differential study of the particle spectra and thermodynamics of the produced system as a function of charged-particle multiplicity and transverse spherocity in pp collisions would shed light on the underlying event dynamics. Transverse spherocity, one of the event shape observables, allows to separate the events in terms of jetty and isotropic events. We analyse the identified particle transverse momentum ( p T ) spectra as a function of charged-particle multiplicity and transverse spherocity using Tsallis nonextensive statistics and Boltzmann-Gibbs Blast-Wave (BGBW) model in pp collisions at s = 13 TeV using PYTHIA8 event generator. The extracted parameters such as temperature ( T ), radial flow ( β ), and nonextensive parameter ( q ) are shown as a function of charged-particle multiplicity for different spherocity classes. We observe that the isotropic events approach thermal equilibrium while the jetty ones remain far from equilibrium. We argue that, while studying the QGP-like conditions in small systems, one should separate the isotropic events from the spherocity-integrated events, as the production dynamics are different.

Fast radio bursts are bright, millisecond-scale radio flashes of yet unknown physical origin. Recently, their extragalactic nature has been demonstrated and an increasing number of the sources have been found to repeat. Young, highly magnetized, isolated neutron stars - magnetars - have been suggested as the most promising candidates for fast radio burst progenitors owing to their energetics and high X-ray flaring activity. Here we report the detection with the Konus-Wind of a hard X-ray event of April 28, 2020, temporarily coincident with a bright, two-peak radio burst from the Galactic magnetar SGR~1935+2154 with properties remarkably similar to those of fast radio bursts. We show that two peaks of the double-peaked X-ray burst coincide in time with the radio peaks, confirming that the X-ray and radio emission most likely have a common origin. Thus, this is the first simultaneous detection of a fast radio burst from a Galactic magnetar and its high-energy counterpart. The total energy emitted in X-rays in this burst is typical of bright short magnetar bursts, but an unusual hardness of its energy spectrum strongly distinguish the April 28 event among multiple "ordinary" flares detected from SGR~1935+2154 previously. This, and a recent non-detection of radio emission from about one hundred typical soft bursts from SGR 1935+2154 favors the idea that bright, FRB-like magnetar signals are associated with rare, hard-spectrum X-ray bursts, which implied rate ($\sim$ 0.04 yr$^{-1}$ magnetar$^{-1}$) appears consistent with the rate estimate of SGR 1935+2154-like radio bursts (0.007 - 0.04 yr$^{-1}$ magnetar$^{-1}$)., 25 pages, 6 figures, 4 tables

Fast radio bursts (FRBs) are short pulses observed in radio band from cosmological distances. One class of models invoke soft gamma-ray repeaters (SGRs), or magnetars, as the sources of FRBs. Some radio pulses have been observed from some magnetars, however, no FRB-like events had been detected in association any magnetar burst, including one giant flare. Recently, a pair of FRB-like bursts (FRB 200428 hereafter) separated by milliseconds (ms) were detected from the general direction of the Galactic magnetar SGR J1935+2154. Here we report the detection of a non-thermal X-ray burst in the 1-250 keV energy band with the Insight-HXMT satellite, which we identify as emitted from SGR J1935+2154. The burst showed two hard peaks with a separation of 34 ms, broadly consistent with that of the two bursts in FRB 200428. The delay time between the double radio and X-ray peaks is about 8.57 s, fully consistent with the dispersion delay of FRB 200428. We thus identify the non-thermal X-ray burst is associated with FRB 200428 whose high energy counterpart is the two hard peaks in X-ray. Our results suggest that the non-thermal X-ray burst and FRB 200428 share the same physical origin in an explosive event from SGR J1935+2154., 24 pages, 9 figures, 6 tables; initial submission to a journal on May 9th, 2020. Significant changes include updated localization and detailed spectral evolution of the X-ray burst, and better determination of the two narrow X-ray peaks corresponding to the two radio pulses. Conclusions are strengthened. Nature Astronomy online on Feb. 18, 2021