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At least 73 records · Page 4

Search for the 𝑌⁡(2175) in the Photoproduction Cross Section Measurement of 𝛾⁢𝑝 → 𝜙⁢𝜋 + ⁢𝜋 − ⁢𝑝 at GlueX

Based on 334 pb −1 of photoproduction data collected with the GlueX detector at Jefferson Lab, we have measured for the first time the cross section of the exclusive reaction 𝛾+𝑝→𝜙⁡(1020)⁢𝜋 + ⁢𝜋 − ⁢𝑝 by reconstructing the final state 𝐾 +⁢ 𝐾 − ⁢𝜋 + ⁢𝜋 − ⁢𝑝 produced with a photon beam of energies between 8.0 and 11.6 GeV. Based on the measured differential cross section, we have performed a search for the strangeoniumlike exotic candidate 𝑌⁡(2175), recently renamed to 𝜙⁡(2170). This state has been reported by different 𝑒 + ⁢𝑒 − annihilation experiments and it is addressed here for the first time in a photoproduction experiment. We do not find evidence for this state when using the resonance parameters quoted by the Particle Data Group and provide upper limits on the photoproduction cross section. Instead, we find a structure at a mass of 𝑚⁡(𝜙⁢𝜋 + ⁢𝜋 − ) = 2.24 GeV/𝑐 2 with a statistical significance of about 5⁢𝜎. The parameters of this structure differ from those quoted by the Particle Data Group for the 𝜙⁡(2170) and are consistent with a previous observation in 𝑒 + ⁢𝑒 − annihilation. In addition, there is evidence for a second structure at 1.82 GeV/𝑐 2 .

Exotic mesons↗

Mixing effects on spectroscopy and partonic observables of heavy mesons with logarithmic confining potential in a light-front quark model

Using the variational principle, we systematically investigate the mass spectra and wave functions of both 1⁢𝑆 and 2⁢𝑆 state heavy pseudoscalar (𝑃) and vector (𝑉) mesons within the light-front quark model. This approach incorporates a Coulomb plus logarithmic confinement potential to accurately describe the constituent quark and antiquark dynamics. Additionally, spin hyperfine interactions are introduced perturbatively to compute the masses of pseudoscalar and vector mesons. The present analyses of the 1⁢𝑆 and 2⁢𝑆 states require the consideration of mixing between them to account for empirical constraints. These constraints include the mass gap Δ⁢𝑀 𝑃 >Δ⁢𝑀 𝑉 , where Δ⁢𝑀 𝑃⁡(𝑉) =𝑀$^{2⁢𝑆}_{𝑃⁡(𝑉)}$−𝑀$^{1⁢𝑆}_{𝑃⁡(𝑉)}$ and the hierarchy of the decay constants 𝑓 1⁢𝑆 >𝑓 2⁢𝑆 . We find the optimal value of the mixing angle to be 𝜃 =1⁢8°, significantly enhancing the consistency between our spectroscopic predictions and the experimental data compiled by the Particle Data Group. Furthermore, based on the predicted mass, the newly observed resonance 𝐵 𝐽⁡ (5840) could be assigned as a 2 1⁢ 𝑆 0 state in the 𝐵 meson family. The study also reports various pertinent observables, including twist-two distribution amplitudes, electromagnetic form factors, charge radii, 𝜉 moments, and transition form factors that are found to be consistent with both available lattice simulations and experimental data. In addition, our predicted branching ratios for the channels of 𝐵 + →𝜏 + ⁢𝜈 𝜏 as well as rare decays of 𝐵 0 and 𝐵$^0_𝑠$ appear in accordance with experimental data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Calculating beam extinction in a pulsed proton beam using FPGA-based peak detection

The Mu2e experiment at Fermilab imposes stringent requirements on the elimination of out-of-time beam in its pulsed proton beam, a requirement known as “extinction”. Utilizing a new μTCA-based FPGA data acquisition system, we recorded live particle data from scattered particles incident on an array of quartz Cherenkov radiators and photomultiplier tubes to measure the extinction in the inter-pulse gaps in the pulsed proton beam. Minuscule errors in the derived signal period can make a measurement of the extinction impossible, so after taking a Fourier transform, further optimizations on the period were done based on the assumption that the signal period is stable over the full time of the beam spill while it is being resonantly extracted. After these optimizations, the beam extinction was shown to be on the level of 10^3.

Hensley, Ryan [UC, Davis]↗

Light Elements $R$-matrix Analyses with the SAMMY code towards the Foundation of Charged-particle Nuclear Data Libraries [Slides]

This presentation covers newly developed SAMMY module for inverse channel transformation. Additionally covered is the R-matrix analysis of 7 Be compound nucleus and the R-­matrix analysis of 17 O compound nucleus. Further touched on is the evaluated Nuclear Data File generation and processing with the AMPX code. The presentation concludes with talks on future evaluation work and tests on light nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Data-driven particle dynamics: Structure-preserving coarse-graining for emergent behavior in non-equilibrium systems

Multiscale systems are ubiquitous in science and technology, but are notoriously challenging to simulate as short spatiotemporal scales must be appropriately linked to emergent bulk physics. When expensive high-dimensional dynamical systems are coarse-grained into low-dimensional models, the entropic loss of information leads to emergent physics which are dissipative, history-dependent, and stochastic. To machine learn coarse-grained dynamics from time-series observations of particle trajectories, we propose a framework using the metriplectic bracket formalism that preserves these properties by construction; most notably, the framework guarantees discrete notions of the first and second laws of thermodynamics, conservation of momentum, and a discrete fluctuation-dissipation balance crucial for capturing non-equilibrium statistics. We introduce the mathematical framework abstractly before specializing to a particle discretization. As labels are generally unavailable for entropic state variables, we introduce a novel self-supervised learning strategy to identify emergent structural variables. We validate the method on benchmark systems and demonstrate its utility on two challenging examples: (1) coarse-graining star polymers at challenging levels of coarse-graining while preserving non-equilibrium statistics, and (2) learning models from high-speed video of colloidal suspensions that capture coupling between local rearrangement events and emergent stochastic dynamics. We provide open-source implementations in both PyTorch and LAMMPS, enabling large-scale inference and extensibility to diverse particle-based systems.

Computational Engineering, Finance, and Science (c↗

The magnetosphere of Uranus - Hot plasma and radiation environment

Inferences are drawn on the morphology and composition of the Uranus magnetosphere based on low-energy charged particle data collected by Voyager 2. Proton and electron energies in the magnetosphere attained energies of 4 and 1.2 MeV, respectively, although electron intensities surpassed the proton intensities at most energy levels. Protons dominated in the ion energy regime 0.6-1.0 MeV. The ion and electron spectra were Maxwellian below about 200 keV and had a power law distribution at energies over 590 keV. The power law was reduced by a factor of nearly three inside the orbit of Miranda. The proton population is dense enough to polymerize CO and CH4 ice surfaces within 10,000-100,000 yr. The data indicated that the particles are swept out at least to the orbit of Titania by the satellites. The morphology of the magnetosphere closely resembles that around Jupiter, except that plasma sheet distorsion from particle loading is negligible in regions within 15 Uranus radii.

Krimigis, S. M.↗

Active Flow Control for Trailing Edge Flap Separation

Active flow control (AFC) in the form of sweeping jet (SWJ) excitation and discrete steady jet excitation is used to control the flow separation on an NACA 0015 semispan wing with a deflected, simple-hinged, trailing edge flap. This geometry has been the focus of several recent publications that investigated methods to improve the efficiency of sweeping jet actuators. In the current study, the interaction of the AFC excitation with the separated flowfields present at several flap deflection angles was examined. Previous studies with this model have been limited to a maximum flap deflection angle of 40°. The flap deflection range was extended to 60! because systems studies have indicated that a high-lift system with simple-hinged flaps may require larger flap deflections than the Fowler flaps found on most high-lift systems. The results obtained at flap deflection angles of 20°, 40°, and 60° are presented and compared. Force and moment data, Particle Image Velocimetry (PIV) data, and steady and unsteady surface pressure data are used to describe the flowfield with and without AFC. With a flap deflection of 60°, increasing the SWJ actuator momentum at the flap shoulder increased lift due to an increase in circulation but did not completely eliminate the recirculation region above the flap surface. AFC using the discrete steady jet actuators of this study increased lift as well but required more mass flow than the SWJ actuators and had a detrimental effect on lift at the highest mass flow level tested. PIV results showed that the angle between the excitation and the flap surface was not optimal for attaching the separated shear layer.

Melton, LaTunia Pack↗

Solar flare shocks in interplanetary space and solar flare particle events

Data on particle events resulting from three solar flares are examined to determine the effect of shocks on the population of protons at energies not less than 30 MeV. The arrival of the shock is found to mark the start of the decay phase of the particle event, and changes in particle anisotropy are found to be related to features in the shock structure. Two distinct modes of particle propagation are found to exist: a direct component, and a second component which has a time scale of days and is seen in two of the flares which also produced interplanetary shock. In addition, a model is described in which the protons are accelerated by the shocks, and it is shown to be in agreement with observations.

Evenson, P.↗

Rapid Succession of Sep Events Associated With A Series of Euv Jets: Solar Orbiter, Stereo-A and Near-Earth Spacecraft Observations

A series of near-relativistic solar electron events was observed on November 9 to 15, 2022 by STEREO-A at 0.96 au, by near-Earth spacecraft such as ACE, Wind and SOHO at ⇠0.99 au, and by Solar Orbiter at heliocentric distances ranging from 0.59 to 0.66 au. At least 22 electron intensity enhancements at energies >10 keV were clearly distinguishable in the particle data collected by the Energetic Particle Detector (EPD) suite of instruments on board Solar Orbiter, with 12 of these events occurring on 11 November 2022. Several of these electron events were accompanied by <10 MeV proton and <⇠2 MeV/n heavy ion intensity enhancements. The origin of this rapid succession of particle events is a series of jet-like eruptions detected in extreme ultraviolet (EUV) observations from the vicinity of active region AR 13141 that were closely associated with type III bursts in the decametric-hectometric range. We find a close association between the EUV jets, type III radio bursts and the release of near relativistic electrons. The events on 9 November and late on 14 November are particularly interesting in that they were just evident at electron energies below ⇠30 keV, were rich in heavy ions with energies below ⇠1 MeV/n, associated with type III radio bursts at frequencies below ⇠1.0 MHz, and originated at EUV solar eruptions lacking a clear jet. By combining remote and in-situ data from the three viewpoints (Solar Orbiter and STEREO-A were ⇠20 degrees and ⇠15 degrees east of Earth, respectively), we analyze the origin of this sequence of events, determine the interplanetary context where they were observed, and investigate the interplanetary transport of electrons to the different spacecraft.

D Loyo↗

Data catalog of satellite experiments

The availability of space science data, a description of the data, and a description of the services supplied by the National Space Science Data Center (NSSDC) is presented. A series of cumulative indexes that reference the data descriptions contain: (1) a chronological listing of all spacecraft, experiments, and data descriptions; (2) an index of all spacecraft described, identified by common names and alternate names; (3) a listing of the original experiment institutions for experiments described; (4) a listing of the investigators associated with the experiments and their current affiliations; and (5) two displays of information about experiment data coverage for fields and particle data and a listing of all experiments sorted by phenomenon measured.

Source record↗

The forecasting center of Meudon, France

Main features of solar activity are described in relation to solar and geophysical forecasting. Spectroheliograms, radio and X-ray data, white light coronal observations, particles data, photospheric images, and photospheric magnetic fields are among the types of data used to identify the active centers and flares of the Sun. Forecasting and identification of geomagnetic activity is also discussed. The forecasting technique is described along with the types of users.

Simon, P.↗

Implications of the GSFC Q3 model for trapped particle motion

The Uranus magnetic field model of Connerney et al. (1987), designated GSFC Q3, is used to compute field geometric invariant parameters that determine the adiabatic motion of energetic charged particles trapped in the Uranian magnetosphere, performing computations only for points located along the Voyager 2 flyby trajectory. The L-shell values computed along the Voyager-2 trajectory were compared with L shell values corresponding to the orbital positions for the Uranian satellites Ariel, Umbriel, Miranda, and Titania for a time period centered on the time of the Voyager 2 closest approach to the planet. Bimodal distributions of L minima asociated with the orbital motion of the moons are obtained, thus complicating the model predictions and correlations with charged particle data. The location of charged particle absorption signatures associated with the sweeping effects of the Uranian satellites is reasonably predicted, but significant discrepancies remain which cannot be explained by Q3 model uncertainties.

Acuna, M. H.↗

Io and its plasma environment

The interaction of Io with its plasma torus and the Jovian magnetic field is described and examined in the context of several currently popular models. Three specific matters are addressed. First, features implied by sub-Alfvenic flow which must be common to all models are discussed. Next, the magnetic signature observed near Io by the Goddard Space Flight Center Voyager 1 magnetometer is examined and it is pointed out that the preliminary estimate of 5,000,000 A current may be an overestimate. Good fits are obtained with alternative current distributions which yield currents as small as 700,000 A through Io. The best fits are obtained for an Alfven Mach number of 0.15, but good fits are also found for Alfven Mach numbers between 0.1 and 0.25. Lastly, the crucial role of charged particle data for probing the near Io interaction is pointed out. Published data from the low energy charged particle (LECP) detector are made to suggest that Io has an intrinsic magnetic field of magnitude comparable with earlier estimates. Predictions are made which can test this picture as further data become available.

Southwood, D. J.↗

Simultaneous satellite and riometer studies

The expected 30 and 50 MHz riometer absorption was calculated for the 7 June, 25 September and 2 November 1969 solar events using data from the McDonnell Douglas charged particle experiment on the polar orbiting OGO-6 Satellite. Excellent agreement was found between measured polar cap riometer absorption during the events and absorption calculated from detailed particle data obtained on the satellite passing over the riometer. Electrons are found to contribute the greater part of the 30 MHz absorption before the peak of the 2 November 1969 event; at all other times protons produce most of the absorption. The alpha-particle contribution is negligible in all cases.

Baker, M. B.↗

Microstructure of magnetic reconnection in earth's magnetotail

The structure of heated electron reconnection events associated with magnetic substorm events in the earth's magnetotail is examined using IMP 8 spacecraft and ground-based magnetometer, plasma analyzer and spectroscopic data. Plasma, magnetic field and energetic particle data for five events are presented. Reconnection is shown to occur in two phases: preheating and heating. In preheating, lasting about 5 min, a strong tailward plasma flow appears and ends with electron heating. A 1-2 min heating phase starts with electron heating and ends with plasma sheet drop out and/or decay of the electron temperature to pre-event levels. The heating pulse is always connected with a Bx reversal at 30 earth radii tailward, where the reconnection occurs.

Bieber, J. W.↗