Entanglement entropy in a time-dependent holographic Schwinger pair creation
Not Available
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
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Results for “Physical radiation effects”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Directional Recoil Detection
Searches for dark matter–induced recoils have made impressive advances in the last few years. Yet the field is confronted by several outstanding problems. First, the inevitable background of solar neutrinos will soon inhibit the conclusive identification of many dark matter models. Second, and more fundamentally, current experiments have no practical way of confirming a detected signal's Galactic origin. The concept of directional detection addresses both of these issues while offering opportunities to study novel dark matter– and neutrino-related physics. The concept remains experimentally challenging, but gas time projection chambers are an increasingly attractive option and, when properly configured, would allow directional measurements of both nuclear and electron recoils. In this review, we reassess the required detector performance and survey relevant technologies. Fortuitously, the highly segmented detectors required to achieve good directionality also enable several fundamental and applied physics measurements. As a result, we comment on near-term challenges and how the field could be advanced.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Directed Flow and the Chiral Magnetic Effect in Ultrarelativistic Collisions with CMS at the LHC (Final Technical Report for DOE Grant # DE-SC0021080)
This Final Technical Report covers the years of activity for the Grant DE-SC0021080. It reflects the efforts of Alice Mignerey, the PI, Timothy Koeth, the co-PI, graduate students Eric Adams and Samuel Lascio, and undergraduates Alyssa Marinelli and Max Bernard. Results from three separate aspects of the project are presented: 1) understanding the radiation damage of the positive and negative sides of the Spectator Reaction Plane detector (SRPD) for data from the 2018 PbPb run at the CERN LHC. 2) Results of the directed flow in PbPb collisions at $\sqrt{SNN}$ = 5.02 TeV. 3) Activation studies of the sectors of the positive side of the SRPD and radiation damage studies on fused quartz using the Maryland 4-MeV electron accelerator. The most significant result is that the reaction plane derived directed flow for both participant and spectator reaction planes is many times larger than that obtained by ALICE.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Representing Fine‐Scale Topographic Effects on Surface Radiation Balance in Hyper‐Resolution Land Surface Models
Land surface models are increasingly used to simulate land surface processes at hyper-spatial resolutions (e.g., ∼1 km). As model resolution increases, grid-scale topographic effects on surface radiation fluxes and their interactions between adjacent grids become more pronounced. However, current land surface models routinely neglect the fine-scale topographic effects on surface radiation balance. This study developed physically-based and computationally-efficient parameterizations (fineTOP) that explicitly resolve fine-scale topographic effects on downward shortwave and longwave radiation as well as land surface radiative properties. The newly developed parameterizations were implemented and tested in the Energy Exascale Earth System Model (E3SM) Land Model (ELM). Multi-decadal km-resolution ELM simulations over the California Sierra Nevada show that fine-scale topography significantly impacts the surface energy balance and snow processes across seasons. Slope determines the magnitude of topographic effects, while aspect controls their sign. For slopes larger than 30°, topography-induced change in annual surface temperature can be as large as 3.3 K. Regionally, the mean value and standard deviation of topography-induced changes in annual surface temperature are −0.22 ± 0.38 K and +0.25 ± 0.37 K over north-facing and south-facing slopes, respectively. Topography-induced changes in surface radiative properties account for 3.5% ± 13.8% of total topographic effects on annual net radiation. With fineTOP, ELM captures the aspect-dependence of snow cover fraction, snow water equivalent, and land surface temperature found in MODIS satellite observations and a snow reanalysis data set, while the default ELM fails to capture this phenomenon. The enhanced capability to represent fine-scale topographic effects on surface radiation balance can be used to advance understanding of the role of fine-scale topography in land surface processes and land-atmosphere interactions over mountainous regions.
Hao, Dalei [Pacific Northwest National Laboratory ↗
Features of multilayer mirror application for focusing and collimating X-rays from inverse Compton scattering sources
We have analysed the use of X-ray interference multilayer mirrors as the elements of a focusing scheme for a compact source based on inverse Compton scattering. An algorithm is proposed for selecting mirror parameters, which takes into account the properties of the radiation source. The dependence of wavelength on the viewing angle and the energy line broadening for a fixed viewing angle are found to be the main limitations in the use of multilayer mirrors. Efficient radiation collection calls for the application of broadband mirrors. It is shown that the efficiency of multilayer mirrors in a Kirkpatrick – Baez X-ray focusing setup exceeds that of total external reflection mirrors by an order of magnitude, and that stack multilayer mirrors offer a small advantage over the periodic ones. The overall efficiency of source radiation collection in the photon energy range ΔE = 10 – 12 keV amounts to 12 % for the two-mirror Kirkpatrick – Baez setup. For a spectral region with a bandwidth ΔE/E = 3 %, the efficiency ranges up to 69 %. (paper)
07 ISOTOPE AND RADIATION SOURCES↗
Nuclear data for space exploration
Understanding the harmful effects of galactic cosmic rays (GCRs) on space exploration requires a substantial amount of nuclear data. Specifically, the interaction of energetic GCR charged particles with spacecraft materials generates secondary radiations that, through energy deposition, can harm astronauts and electronic systems. By identifying the gaps in our knowledge of the relevant nuclear data—such as interaction cross sections—and identifying ways to fill those gaps—with measurements, compilations, evaluations, dissemination, reaction modeling, sensitivity studies, and uncertainty quantification—the safety and viability of space exploration can be improved. This work surveys the state of the art in this interdisciplinary field and identifies promising collaborative research topics that have significant potential to advance our understanding of the effects of the space radiation environment on space exploration.
42 ENGINEERING↗
Air quality impact of the Northern California Camp Fire of November 2018
The Northern California Camp Fire that took place in November 2018 was one of the most damaging environmental events in California history. Here, we analyze ground-based station observations of airborne particulate matter that has a diameter <2.5 µm (PM 2.5 ) across Northern California and conduct numerical simulations of the Camp Fire using the Weather Research and Forecasting model online coupled with chemistry (WRF-Chem). Simulations are evaluated against ground-based observations of PM 2.5 , black carbon, and meteorology, as well as satellite measurements, such as Tropospheric Monitoring Instrument (TROPOMI) aerosol layer height and aerosol index. The Camp Fire led to an increase in Bay Area PM 2.5 to over 50 µg m –3 for nearly 2 weeks, with localized peaks exceeding 300 µg m –3 . Using the Visible Infrared Imaging Radiometer Suite (VIIRS) high-resolution fire detection products, the simulations reproduce the magnitude and evolution of surface PM 2.5 concentrations, especially downwind of the wildfire. The overall spatial patterns of simulated aerosol plumes and their heights are comparable with the latest satellite products from TROPOMI. WRF-Chem sensitivity simulations are carried out to analyze uncertainties that arise from fire emissions, meteorological conditions, feedback of aerosol radiative effects on meteorology, and various physical parameterizations, including the planetary boundary layer model and the plume rise model. Downwind PM 2.5 concentrations are sensitive to both flaming and smoldering emissions over the fire, so the uncertainty in the satellite-derived fire emission products can directly affect the air pollution simulations downwind. Our analysis also shows the importance of land surface and boundary layer parameterization in the fire simulation, which can result in large variations in magnitude and trend of surface PM 2.5 . Inclusion of aerosol radiative feedback moderately improves PM 2.5 simulations, especially over the most polluted days. Results of this study can assist in the development of data assimilation systems as well as air quality forecasting of health exposures and economic impact studies.
54 ENVIRONMENTAL SCIENCES↗
Superbolts: The Most Powerful Optical Signals Generated by Lightning [Slides]
The most powerful optical lightning events are termed “superbolts." Superbolts can arise from physical lightning phenomena or radiative transfer effects. The most intense superbolts are caused by long-horizontal “megaflashes” in stratiform clouds that are particularly effective optical emitters. The scale, intensity, and rarity of superbolts and megaflashes make them difficult to observe. RF-powerful events recently labeled “superbolts” are a different phenomenon.
54 ENVIRONMENTAL SCIENCES↗
Pulsed-Power Innovations for Next-Generation, High-Current Drivers
There are proposals to build larger high-current drivers to be used for high-energy-density physics (HEDP), inertial confinement fusion (ICF), radiation effects testing, and basic science. Drivers significantly larger than the Z Machine at Sandia National Laboratories, Albuquerque, NM, USA, encounter increasing difficulties in water power flow, insulator performance, and vacuum power flow. The physics requirements of imploding loads limit a designer’s flexibility in choosing machine parameters, such as current rise time, driving impedance, and total inductance. This article enumerates these physics constraints and shows how they impact driver design. Here, we conclude that advances in pulsed-power capabilities are needed to control risk and to build a cost-effective driver at peak currents of ~60 MA.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Event shape selection method in search of the chiral magnetic effect in heavy-ion collisions
Not Available
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Preliminary study of auto-differentiation algorithm in beam dynamics with stochastic process
Modern particle accelerator optimization requires sophisticated computational methods to address the inherently stochastic nature of beam dynamics. This research develops a framework applying AD to SDEs that specifically addresses beam dynamics challenges in particle accelerators, focusing on accurately modeling and optimizing beam behavior in regimes dominated by stochastic processes. By incorporating key physical phenomena such as synchrotron radiation, wakefield effects, and quantum excitation, the framework aims to provide auto differentiation on the figure of merit of the phase space evolution and beam dynamics. The methodology will enable effective optimization method in a dynamic system with stochastic process.
Accelerator Physics↗
Nonlocal Structure of the Leading Order ab initio Effective Potentials for Proton Elastic Scattering from Light Nuclei
Based on the spectator expansion of the multiple scattering series we employ a chiral next-to-next-to-leading order (NNLO) nucleon-nucleon interaction on the same footing in the structure as well as in the reaction calculation to obtain an in leading-order consistent effective potential for nucleon-nucleus elastic scattering, which includes the spin of the struck target nucleon. Here, as an example we present proton scattering off $^{12}$C.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Fourier coefficients of noninterdependent collective motions in heavy-ion collisions
Here, we present a scenario in heavy-ion collisions where different modes of collective motions are noninterdependent, driven by factorized actions in the created nuclear medium. Such physics mechanisms could each dominate at a distinct evolution stage, or coexist simultaneously. If the probability of particle emission is modulated by each nondependent collective motion with a single-harmonic Fourier expansion, the particle azimuthal distribution should be the product of all these expansions. Consequently, nonleading cross terms between collectivity modes appear, and their contributions to experimental observables could be significant. In particular, we argue that the chiral magnetic effect (CME) and elliptic flow can develop separately, with their convolution affecting the observable that is sensitive to the shear-induced CME. We will use the event-by-event anomalous-viscous fluid dynamics model to illustrate the effects of this scenario. Besides giving insights into searches for the CME, we also propose feasible experimental tests based on conventional flow harmonics, and demonstrate the emergence of nonleading cross terms with a multiphase transport model.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Chiral Magnetic Effects in Nuclear Collisions
The interplay of quantum anomalies with strong magnetic fields and vorticity in chiral systems could lead to novel transport phenomena, such as the chiral magnetic effect (CME), the chiral magnetic wave (CMW), and the chiral vortical effect (CVE). In high-energy nuclear collisions, these chiral effects may survive the expansion of a quark–gluon plasma fireball and be detected in experiments. The experimental searches for the CME, the CMW, and the CVE have aroused extensive interest over the past couple of decades. The main goal of this article is to review the latest experimental progress in the search for these novel chiral transport phenomena at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN. Future programs to help reduce uncertainties and facilitate the interpretation of the data are also discussed.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Nucleon form factors and parton distributions in nonlocal chiral effective theory
In this work, we present a review of recent applications of nonlocal chiral effective theory to hadron structure studies. Starting from a nonlocal meson-baryon effective chiral Lagrangian, we show how the introduction of a correlation function representing the finite extent of hadrons regularizes the meson loop integrals and introduces momentum dependence in vertex form factors in a gauge invariant manner. We apply the framework to the calculation of nucleon electromagnetic form factors, unpolarized and polarized parton distributions, as well as transverse momentum dependent distributions and generalized parton distributions. Assuming that the nonlocal behavior is a general property of all interactions, we also discuss the application to the lepton anomalous magnetic moment in nonlocal QED.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
The metamorphosis of semi-classical mechanisms of confinement: from monopoles on ℝ 3 × S 1 to center-vortices on ℝ 2 × T 2
There are two distinct regimes of Yang-Mills theory where we can demonstrate confinement, the existence of a mass gap, and the multi-branch structure of the effective potential as a function of the theta angle using a reliable semi-classical calculation. The two regimes are deformed Yang-Mills theory on ℝ 3 × S 1 , and Yang-Mills theory on ℝ 2 × T 2 where the torus is threaded by a ’t Hooft flux. The weak coupling regime is ensured by the small size of the circle or torus. In the first case the confinement mechanism is related to self-dual monopoles, whereas in the second case self-dual center-vortices play a crucial role. These two topological objects are distinct. In particular, they have different mutual statistics with Wilson loops. On the other hand, they carry the same topological charge and action. We consider the theory on ℝ × T 2 × S 1 and extrapolate both the monopole and vortex regimes to a quantum mechanical domain, where a cross-over takes place. Both sides of the cross-over are described by a deformed ℤ N TQFT. On ℝ 2 × S 1 × S 1 , we derive an effective field theory (EFT) of vortices from the EFT of monopoles in the presence of a ’t Hooft flux. This construction is based on a two-stage Higgs mechanism, reducing SU(N) to U(1) N−1 in 3d first, followed by reduction to a ℤ N EFT in 2d in the second step. This result shows how monopoles transmute into center-vortices, and suggests adiabatic continuity between the two confinement mechanisms. The basic mechanism is flux fractionalization: the magnetic flux of the monopoles splits up and is collimated in such a way that 2d Wilson loops detect it as a center vortex.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Directed Flow and the Chiral Magnetic Effect in Ultrarelativistic Collisions with CMS at the LHC (Final Technical Report for DOE Grant # DE-SC0021080)
This Final Technical Report covers the years of activity for the Grant DE-SC0021080. It reflects the efforts of Alice Mignerey, the PI, Timothy Koeth, the co-PI, graduate students Eric Adams and Samuel Lascio, and undergraduates Alyssa Marinelli and Max Bernard. Results from three separate aspects of the project are presented: 1) understanding the radiation damage of the positive and negative sides of the Spectator Reaction Plane Detector (SRPD) for data from the 2018 PbPb run at the CERN LHC. 2) Results of the directed flow in PbPb collisions at √sN N = 5.02 TeV. 3) Activation studies of the sectors of the positive side of the SRPD and radiation damage studies on fused quartz using the Maryland 4-MeV electron accelerator. The most significant result is that the reaction plane derived directed flow for both participant and spectator reaction planes is many times larger than that obtained by ALICE.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Symplectic effective field theory for nuclear structure studies
Here, a Symplectic Effective Field Theory that unveils the observed emergence of symplectic symmetry in atomic nuclei is advanced. Specifically, starting from a simple extension of the harmonic-oscillator Lagrangian, an effective field theory applied against symplectic basis states is shown to yield a Hamiltonian system with one fitted parameter. The scale of the system can be determined self consistently as the ratio of the average volume of a nucleus assumed to be spherical to its volume as determined by the average number of oscillator quanta, which is stretched by the fact that the plane-wave solution satisfies the equations of motion at every order without the need for perturbative corrections. As an application of the theory, results for 20 Ne, 22 Ne and 22 Mg are presented that yield energy spectra, B(E2) values, and matter radii in good agreement with experimentally measured results.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗