High-energy Interactions Research Articles

Mambillikalathil Govind Kumar Menon. 28 August 1928—22 November 2016

M. G. K. Menon, referred to as Goku, was an outstanding particle physicist and an extraordinary statesman of science. He made his major contributions to particle physics during the tortuous years of the unravelling of the full complexity of the families of elementary particles. It was an exciting but perplexing period, and the elucidation of the complexities of the world of elementary particles took the combined efforts of the experimentalists and the theorists. Goku's contributions were central to establishing what was eventually to become the standard picture of elementary particles. He will be remembered for his studies of the two- and three-body decay modes of the charged kaon that gave rise to the ‘τ–θ’ puzzle signalling non-conservation of parity. He coined the evocative phrase ‘associated production’ to describe the creation of kaons and hyperons together in high-energy interactions. He led a team that carried out experiments at great depths underground, and in 1965 they detected an event in which a cosmic-ray neutrino interacted with rock, producing an energetic muon. In the 1980s, with a large detector, also deployed underground, he set a lower bound on the lifetime for the decay of the proton. Menon was a great builder of academic and scientific institutions and a pre-eminent advocate for science. Accordingly, he stimulated and participated actively in building up the scientific and technological infrastructure in independent India, initially as the secretary of the Government of India and subsequently as the minister of state for science and technology. As the president of the International Council of Scientific Unions, he spearheaded its participation in the policymaking body of the United Nations. He was at various times the president of the three leading academies of sciences in India and a founding member and vice-president of the World Academy of Sciences. He was a gentle and loving family man and an energetic and engaged scientific colleague.

Large heat-capacity jump in cooling-heating of fragile glass from kinetic Monte Carlo simulations based on a two-state picture.

The specific-heat capacity c_{v} of glass formers undergoes a hysteresis when subjected to a cooling-heating cycle, with a larger c_{v} and a more pronounced hysteresis for fragile glasses than for strong ones. Here we show that these experimental features, including the unusually large magnitude of c_{v} of fragile glasses, are well reproduced by kinetic Monte Carlo and equilibrium study of a distinguishable particle lattice model incorporating a two-state picture of particle interactions. The large c_{v} in fragile glasses is caused by a dramatic transfer of probabilistic weight from high-energy particle interactions to low-energy ones as temperature decreases.

Investigation Ability of Two-Dimensional Nano Materials for Detection Toxic Gases

In this study, pure graphene nano-ribbon were used to detect toxic gases under study, which are carbon monoxide, hydro cyanide and methane. The study focused on describing graphene nano-ribbons as sensors for these gases and their use in environmental applications. Quantitative computing methods have been used to calculate the properties of the ground state by density function theory (DFT) and the properties of the stationary state, it was computed by using the time-dependent Schrödinger equation. Ground-state calculations include geometric optimization, total energy, ionization potential, electron affinity, molecular orbit energies, energy gap, adsorption energy and infrared spectrum. Whereas, the time-dependent Schrödinger equation calculations included the UV-Visible spectrum calculations, in order to characterize them as detectors of toxic gases. It was found by studying the adsorption of pure graphene nano-ribbons is sensitive to carbon monoxide, clearly and higher than hydro cyanide and methane. Also, as a result of the chemical reaction, there is a clear effect on the values of the energy gap, the ionization potential, and other associated properties. The effect of the chemical reaction continues at an adsorption distance of 2 angstroms from the surface. As for the infrared radiation calculations, it showed that the appearance of free radicals of adsorbed gases on the surface of the nano-ribbons is a clear evidence of the occurrence of chemical reaction with high energy. Through the results, the calculations of the UV-visible spectrum showed a clear shift in the computed spectrum at the ranges of high-energy interaction (34.0385-22.3212) and (15.7433-3.3246) electron volts for both nano-ribbons.

Molecular Forces in Liquid-Liquid Extraction.

The phase transfer of ions is driven by gradients of chemical potentials rather than concentrations alone (i.e., by both the molecular forces and entropy). Extraction is a combination of high-energy interactions that correspond to short-range forces in the first solvation shell such as ion pairing or complexation forces, with supramolecular and nanoscale organization. While the latter are similar to the long-range solvent-averaged interactions in the colloidal world, in solvent extraction they are associated with lower characteristic lengths of the nanometric domain. Modeling of such complex systems is especially complicated because the two domains are coupled, whereas the resulting free energy of extraction is around kBT to guarantee the reversibility of the practical process. Nevertheless, quantification is possible by considering a partitioning of space among the polar cores, interfacial film, and solvent. The resulting free energy of transfer can be rationalized by utilizing a combination of terms which represent strong complexation energies, counterbalanced by various entropic effects and the confinement of polar solutes in nanodomains dispersed in the diluent, together with interfacial extractant terms. We describe here this ienaics approach in the context of solvent extraction systems; it can also be applied to further complex ionic systems, such as membranes and biological interfaces.

Effect of the uncertainty in the hadronic interaction models on the estimation of the sensitivity of the Cherenkov telescope array

Imaging atmospheric Cherenkov telescopes (IACTs) are ground-based indirect detectors for cosmic gamma rays with energies above tens of GeV. The major backgrounds for gamma-ray observations in IACTs are cosmic-ray charged particles. The capability to reject these backgrounds is the most important factor determining the gamma-ray sensitivity of IACT systems. Monte Carlo simulations are used to estimate the residual background rates and sensitivity of the systems during the design and construction phase. Uncertainties in the modeling of high-energy hadronic interactions of cosmic rays with nuclei in the air propagate into the estimates of residual background rates and subsequently into the estimated instrument sensitivity. We investigate the influence of the difference in the current hadronic interaction models on the estimated gamma-ray sensitivity of the Cherenkov Telescope Array using four interaction models (QGSJET-II-03, QGSJET-II-04, EPOS-LHC, and SIBYLL2.3c) implemented in the air shower simulation tool CORSIKA. Variations in background rates of up to a factor 2 with respect to QGSJET-II-03 are observed between the models, mainly due to differences in the π 0 production spectrum. These lead to ∼30% differences in the estimated gamma-ray sensitivity in the 1–30 TeV region, assuming a 50 h observation of a gamma-ray point-like source. The presented results also show that IACTs have a significant capability in the verification of hadronic interaction models.

Calibration of the underground muon detector of the Pierre Auger Observatory

To obtain direct measurements of the muon content of extensive air showers with energy above 1016.5 eV, the Pierre Auger Observatory is currently being equipped with an underground muon detector (UMD), consisting of 219 10 m2-modules, each segmented into 64 scintillators coupled to silicon photomultipliers (SiPMs). Direct access to the shower muon content allows for the study of both of the composition of primary cosmic rays and of high-energy hadronic interactions in the forward direction. As the muon density can vary between tens of muons per m2 close to the intersection of the shower axis with the ground to much less than one per m2 when far away, the necessary broad dynamic range is achieved by the simultaneous implementation of two acquisition modes in the read-out electronics: the binary mode, tuned to count single muons, and the ADC mode, suited to measure a high number of them. In this work, we present the end-to-end calibration of the muon detector modules: first, the SiPMs are calibrated by means of the binary channel, and then, the ADC channel is calibrated using atmospheric muons, detected in parallel to the shower data acquisition. The laboratory and field measurements performed to develop the implementation of the full calibration chain of both binary and ADC channels are presented and discussed. The calibration procedure is reliable to work with the high amount of channels in the UMD, which will be operated continuously, in changing environmental conditions, for several years.

Nuclear scattering configurations of onia in different frames

In the scattering of a small onium off a large nucleus at high center-of-mass energies, when the parameters are set in such a way that the cross section at fixed impact parameter is small, events are triggered by rare partonic fluctuations of the onium, which are very deformed with respect to typical configurations. Using the color dipole picture of high-energy interactions in quantum chromodynamics, in which the quantum states of the onium are represented by sets of dipoles generated by a branching process, we describe the typical scattering configurations as seen from different reference frames, from the restframe of the nucleus to frames in which the rapidity is shared between the projectile onium and the nucleus. We show that taking advantage of the freedom to select a frame in the latter class makes possible to derive complete asymptotic expressions for some boost-invariant quantities, beyond the total cross section, from a procedure which leverages the limited available knowledge on the properties of the solutions to the Balitsky-Kovchegov equation that governs the rapidity-dependence of total cross sections. We obtain in this way an analytic expression for the rapidity-distribution of the first branching of the slowest parent dipole of the set of those which scatter. This distribution provides an estimator of the correlations of the interacting dipoles, and is also known to be related to the rapidity-gap distribution in diffractive dissociation, an observable measurable at a future electron-ion collider. Furthermore, our result may be formulated as a more general conjecture, that we expect to hold true for any one-dimensional branching random walk model, on the branching time of the most recent common ancestor of all the particles that end up to the right of a given position.

Using SAR imagery to survey internal solitary wave interactions: A case study off the Western Iberian shelf

Physical oceanography is increasingly relying on satellite remote sensing to survey the perpetually undersampled ocean, whereas the latest Synthetic Aperture Radars (SARs) are moving forward to provide a more continuous monitoring of the ocean. In this study we use a collection of SAR images to document the two-dimensional horizontal structure of Internal Solitary Waves (ISWs) propagating between two large submarine canyons off the Western Iberian Peninsula (between May and October 2018), which are observed to intersect approximately along the mid-shelf and originate a naturally-occurring interaction hotspot between different ISW packets. ISW interactions are well documented in theory and in laboratorial and numerical studies, but their observations in the real ocean are limited to airborne observations over the Strait of Georgia. The frequent SAR imagery of interacting ISWs in this region provides additional case studies to the literature, and we investigate if an energy proxy taken from their sea surface signatures can be used as an indicator for high-energy interaction events (e.g. when comparing with a non-interacting background). In particular, a quasi-synergetic event captured both in SAR and in a moored thermistor chain reveals that the often used weakly nonlinear theory for small-amplitude waves may underestimate the amplitudes measured in the waves’ interacting sections. ISWs provide the largest vertical displacements and velocities in the ocean. Understating how their vertical structure changes during wave-wave interactions may have important implications in the broader spectrum of ocean sciences, and SARs are shown in this study to be a first-approach tool to survey this frequent phenomenon in coastal regions.

The Mini-CAPTAIN liquid argon time projection chamber

This manuscript describes the commissioning of the Mini-CAPTAIN liquid argon detector in a neutron beam at the Los Alamos Neutron Science Center (LANSCE), which led to a first measurement of high-energy neutron interactions in argon. The Mini-CAPTAIN detector consists of a Time Projection Chamber (TPC) with an accompanying photomultiplier tube (PMT) array sealed inside a liquid-argon-filled cryostat. The liquid argon is constantly purified and recirculated in a closed-loop cycle during operation. The specifications and assembly of the detector subsystems and an overview of their performance in a neutron beam are reported.

A data-driven event generator for Hadron Colliders using Wasserstein Generative Adversarial Network

Highly reliable Monte-Carlo event generators and detector simulation programs are important for the precision measurement in the high energy physics. Huge amounts of computing resources are required to produce a sufficient number of simulated events. Moreover, simulation parameters have to be fine-tuned to reproduce situations in the high-energy particle interactions which is not trivial in some phase spaces in physics interests. In this paper, we suggest a new method based on the Wasserstein Generative Adversarial Network (WGAN) that can learn the probability distribution of the real data. Our method is capable of event generation at a very short computing time compared to the traditional MC generators. The trained WGAN is able to reproduce the shape of the real data with high fidelity.

Specific Li+ sites in a nanoporous carbon for enhanced light hydrocarbons storage and separation: GCMC and DFT simulations

The storage and separation of light hydrocarbons (C1/C2/C3) is an important process in the petrochemical industry, but it brings considerable technical challenges. Here, we have examined the performance of Li-doped nanoporous carbon (NPC) in separation of C2 and C3 over C1 using Grand Canonical Monte Carlo calculations (GCMC), and explored the mechanism for adsorptive separation by density functional theory (DFT). In the meantime, the established model and selected force field parameters were verified through experimental data to be feasible for the storage and separation of light hydrocarbons on nanoporous carbons (NPCs). The calculation results show that the C3/C1 selectivity of NPC and NPC-OH is higher than C2/C1 selectivity. However, it is found that C2H2/CH4, C2H4/CH4 and C3H6/CH4 selectivity of NPC-Li is around 174, 71 and 336, which is higher selectivity than that of NPC (4, 7 and 79) and NPC-OH (6, 8 and 77). The enhancement of C2H2, C2H4 and C3H6 separation over CH4 is mainly due to the influences of the high adsorption energy and strong electrostatic interaction. It has been proved that the doping of Li+ into NPC is a promising adsorbent for the adsorption and separation of light hydrocarbons, and provides a novel insight for the design and development of light hydrocarbons separation materials.

Probing resonance states in high-energy interaction: a novel approach using complex network technique based on symmetry scaling

Traditionally invariant-mass/transverse-momentum methods were being used to probe various resonance-states in high-energy-collision. Here, we have done scaling analysis by implementing complex-network-based-method (a chaos-based-approach) of visibility-graph to analyze different resonance-states. In the process we use scaling-exponent [power of scale-freeness-of-visibility-graph (PSVG)] calculated from the aforementioned graph. The method is applied to analyze the fractal behavior of pseudo-rapidity-space of the produced dimuons from the events produced in p–p collision at 7 and 8 TeV from CMS collaboration for different ranges of invariant mass of the dimuons. It is found that the fluctuation-pattern of the pseudorapidity-spaces with different ranges of invariant mass has inherent scale-freeness and shows high degree of self-similarity and fractal nature. Moreover, the experiment reveals that the scaling pattern, degree-of-scale-freeness and fractal na ture of the fluctuation differ with different pseodorapidity-space having different ranges of invariant-mass. This change in scaling behavior is reflected in the values of (PSVG) extracted from the corresponding pseudorapidity-space. These different degree of changes in the simple yet rigorous parameter (PSVG) may be indicative of the formation of various resonance-like states(producing di-leptons) and other unusual phenomena. We propose that this method may detect the resonance states in various high energy interactions without using conventional methods of invariant-mass/transverse-momentum techniques and also may detect some unusual phenomena like formation of clusters or structures of cascades etc. This paper reports an application of this method to probe resonance states in p–p collision data at 7 and 8 TeV from CMS by analyzing pseudorapidity-space of the produced dimuons without analyzing their invariant-mass-spectrum.

Complete predictions for high-energy neutrino propagation in matter

We present predictions for the interactions of energetic neutrinos with matter as they propagate through Earth towards large-volume detectors. Our results are based on state-of-the-art calculations of the high-energy neutrino-matter interaction cross-sections, which we have implemented in the HEDIS module of GENIE. In addition to the dominant interaction process, deep inelastic scattering off quarks and gluons, we include the relevant subdominant channels: (in)elastic scattering off the photon field of nucleons, coherent scattering off the photon field of nuclei, as well as the scattering on atomic electrons via the Glashow resonance. Our predictions for the neutrino attenuation rates are provided by a new software package, NuPropEarth. We quantify the dependence of our results on the cross-section model, including nuclear corrections, the incidence angle, and the spectral index, and compare them with other publicly available tools.

Nuclear effects in high-energy neutrino interactions

Neutrino telescopes like IceCube, KM3NeT and Baikal-GVD offer physicists the opportunity to study neutrinos with energies far beyond the reach of terrestrial accelerators. These neutrinos are used to study high-energy neutrino interactions and to probe the Earth through absorption tomography. Current studies of TeV neutrinos use cross sections which are calculated for free nucleons with targets which are assumed to contain equal numbers of protons and neutrons. Here we consider modifications of high-energy neutrino interactions due to two nuclear effects: modifications of the parton densities in the nucleus, referred to here as shadowing, and the effect of non-isoscalar targets, with unequal numbers of neutrons and protons. Both these effects depend on the interaction medium. Because shadowing is larger for heavier nuclei, such as iron, found in the Earth's core, it introduces a zenith-angle dependent change in the absorption cross section. These modifications increase the cross sections by 1-2\% at energies below 100 TeV (antishadowing), and reduce it by 3-4\% at higher energies (shadowing). Nuclear effects also alter the inelasticity distribution of neutrino interactions in water/ice by increasing the number of low inelasticity interactions, with a larger effect for $\nu$ than $\bar\nu$. These effects are particularly large in the energy range below a few TeV. These effects could alter the cross sections inferred from events with tracks originating within the active detector volume as well as the ratio $\nu/\bar\nu$ inferred from inelasticity measurements. The uncertainties in these nuclear effects are larger than the uncertainties on the free-proton cross sections and will thus limit the systematic precision of future high-precision measurements at neutrino telescopes.

Calculation of Long-Range Rapidity Correlations in the Model with String Fusion on a Transverse Lattice

By the model with the fusion of quark-gluon strings on a transverse lattice the correlations between observables from separated rapidity intervals in high-energy hadronic interactions are considered. The asymptotes of the long-range rapidity correlation coefficients between the multiplicities (n–n) and between the event-mean transverse momentum and the multiplicity of charged particles (pt–n) in these observation windows at large string density were explicitly calculated with the additional condition fixing the total number of initial strings. It is shown that this condition, which imitates in our model the fixation of the collision centrality class, has a significant impact on the behavior of the n–n and pt–n correlation coefficients for both homogeneous and inhomogeneous distribution of strings in the transverse plane.

Muon deficit in air shower simulations estimated from AGASA muon measurements

In this work, direct measurements of the muon density at $1000\,\textrm{m}$ from the shower axis obtained by the Akeno Giant Air Shower Array (AGASA) are analysed. The selected events have zenith angles $\theta \leq 36^{\textrm{o}}$ and reconstructed energies in the range $18.83\,\leq\,\log_{10}(E_{R}/\textrm{eV})\,\leq\,19.46$. These are compared to the predictions corresponding to proton, iron, and mixed composition scenarios obtained by using the high-energy hadronic interaction models EPOS-LHC, QGSJetII-04, and Sibyll2.3c. The mass fractions of the mixed composition scenarios are taken from the fits to the depth of the shower maximum distributions performed by the Pierre Auger Collaboration. The cross-calibrated energy scale from the Spectrum Working Group [D. Ivanov, for the Pierre Auger Collaboration and the Telescope Array Collaboration, PoS(ICRC2017) 498 (2017)] is used to combine results from different experiments. The analysis shows that the AGASA data are compatible with a heavier composition with respect to the one predicted by the mixed composition scenarios. Interpreting this as a muon deficit in air shower simulations, the incompatibility is quantified. The muon density obtained from AGASA data is greater than that of the mixed composition scenarios by a factor of $1.49\pm0.11\,\textrm{(stat)}\pm0.18\,\textrm{(syst)}$, $1.54\pm0.12\,\textrm{(stat)}\pm0.18\,\textrm{(syst)}$, and $1.66\pm0.13\,\textrm{(stat)}\pm0.20\,\textrm{(syst)}$ for EPOS-LHC, Sibyll2.3c, and QGSJetII-04, respectively.

An adaptive mesh refinement approach based on optimal sparse sensing

We introduce a new approach for adaptive mesh refinement in which adaptivity is driven by low rank decomposition and optimal sensing of the dynamically evolving flow field. This method seeks an ordered set of locations for mesh adaptation from the instantaneous data-driven basis of an online proper orthogonal decomposition of the velocity, which organizes features into sparse optimal orthogonal modes based on an energy norm. The sensing is achieved via a computationally expedient discrete empirical interpolation method using rank-revealing QR factorization (Drmac and Gugercin SIAM J Sci Comput 38(2):A631–A648, 2016). The methodology is applicable to a wide range of numerical discretizations, and is tested on a spatiotemporally evolving incompressible turbulent jet, a complex wind turbine wake, and supersonic flow over a forward-facing step. The proposed approach is demonstrated to predict accurate velocity statistics and yield significantly smaller grids in comparison to gradient-based methods. The algorithm is seen to focus refinement in the vicinity of dynamically significant regions such as those characterized by high turbulence kinetic energy, coherent structures and shock interactions. Moreover, the approach does not require parameters or thresholds, which may be difficult to obtain for complex flows, to be known a priori to facilitate mesh adaptation.

Multiplicity moments using Tsallis statistics in high-energy hadron–nucleus interactions

The study of higher-order moments of a distribution and its cumulants constitute a sensitive tool to investigate the correlations between the particle produced in high-energy interactions. In our previous work, we have used the Tsallis [Formula: see text] statistics, NBD, Gamma and shifted Gamma distributions to describe the multiplicity distributions in [Formula: see text]-nucleus and [Formula: see text]-nucleus fixed target interactions at various energies ranging from [Formula: see text][Formula: see text]GeV to 800[Formula: see text]GeV. In this study, we have extended our analysis by calculating the moments using the Tsallis model at these fixed target experiment data. By using the Tsallis model, we have also calculated the average charged multiplicity and its dependence on energy. It is found that the average charged multiplicity and moments predicted by the Tsallis statistics are in much agreement with the experimental values and indicates the success of the Tsallis model on data from visual detectors. The study of moments also illustrates that KNO scaling hypothesis holds good at these energies.

Observation of Radar Echoes from High-Energy Particle Cascades.

We report the observation of radar echoes from the ionization trails of high-energy particle cascades. Data were taken at the SLAC National Accelerator Laboratory, where the full electron beam (∼10^{9} e^{-} at ∼10 GeV/e^{-}) was directed into a plastic target to simulate an ultrahigh-energy neutrino interaction. The target was interrogated with radio waves, and coherent radio reflections from the cascades were detected with properties consistent with theoretical expectations. This is the first definitive observation of radar echoes from high-energy particle cascades, which may lead to a viable neutrino detection technology for energies ≳10^{16} eV.

Compelling Evidence of Oscillatory Behaviour of Hadronic Multiplicities in the Shifted Gompertz Distribution

Study of charged particle multiplicity distribution in high-energy interactions of particles helps in revealing the dynamics of particle production and the underlying statistical patterns, by which these distributions follow. Several distributions derived from statistics have been employed to understand its behaviour. In one of our earlier papers, we introduced the shifted Gompertz distribution to investigate this variable and showed that the multiplicity distributions in a variety of processes at different energies can be very well described by this distribution. The fact that the shifted Gompertz distribution, which has been extensively used in diffusion theory, social networking and forecasting, has been used for the first time in high-energy physics collisions remains interesting. In this paper, we investigate the phenomenon of oscillatory behaviour of the counting statistics observed in the high-energy experimental data, resulting from different types of recurrence relations defining the probability distributions. We search for such oscillations in the multiplicity distributions well described by the shifted Gompertz distribution and look for retrieval of additional valuable information from these distributions.