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At least 1,225 records · Page 68

A scalable transformer model for real-time decision making in neutron scattering experiments

The U.S. Department of Energy's (DOE's) neutron research facilities at Oak Ridge National Laboratory (ORNL), including the High Flux Isotope Reactor (HFIR) and the Spallation Neutron Source (SNS), are a state-of-the-art neutron scattering facility that allows researchers to study the structure and dynamics of materials at the atomic scale. At the SNS, neutrons are measured using the time-of-flight (TOF) technique as they move through a neutron beamline to interact with a sample. Large volumes of neutron scattering data are collected and recorded in neutron event mode. Optimal productivity of the TOF instrument is limited due to the lack of real-time data analysis tools. The large amount of data generated by the experiments can be challenging to process and analyze in real time, particularly for experiments that require rapid feedback and adjustment of experimental parameters. The regular computer/workstation cannot keep up with the experiment speed to provide real-time feedback to adjust experimental parameters, so connecting the supercomputers available to the neutron facility is necessary to achieve real-time data analysis and experiment steering. To address this challenge, we exploit the Frontier supercomputer at Oak Ridge Leadership Computing Facility (OLCF) to train a scalable temporal fusion transformer model for real-time decision making of TOF neutron scattering experimentation. Here, in this paper, we present the results using Frontier to provide the processing power needed to rapidly process and analyze large volumes of single-crystal diffraction data collected at TOPAZ, a neutron time-of-flight Laue single-crystal diffractometer at the SNS.

97 MATHEMATICS AND COMPUTING↗

Seismoacoustic Explosion Yield and Depth Estimation: Insights from the Large Surface Explosion Coupling Experiment

The Large Surface Explosion Coupling Experiment (LSECE) is a chemical explosion experiment conducted in Yucca Flat at the Nevada National Security Site in 2020. The experiment included two surface detonations of ~1000 kg trinitrotoluene equivalent. The main goal of this experiment was to provide the ground-truth data for seismoacoustic wave excitation by large chemical explosions near the ground surface. The seismic and acoustic energy partitioning between the surface is strongly governed by the depth or height of explosions, and either seismic or acoustic-only analysis may have inherent ambiguity in determining explosion yield and depth simultaneously. Previous studies suggested that joint seismoacoustic analysis can resolve the trade-off and reduce the uncertainty of yield and depth estimation dramatically. Here we demonstrate the capability of seismoacoustic analysis to improve the accuracy of explosion yield and depth estimation with the LSECE data. Local acoustic wave propagation in the atmosphere can be substantially affected by constantly varying weather conditions. Consisting of two detonations before dawn and in the afternoon, LSECE provides unique data to evaluate the model accuracy of acoustic wave propagation and seismoacoustic energy partitioning depending on local atmospheric conditions. We quantitatively evaluate the accuracy of yield and depth estimation depending on atmospheric variability and the improvement achieved by the joint seismoacoustic approach.

58 GEOSCIENCES↗

The Accelerator and Beam Physics of the Muon g-2 Experiment at Fermilab

The physics case of the Muon g-2 Experiment at Fermilab is outstanding and has recently attracted significant attention from its first official results. Although its measurements involve high energy physics methods, such as counting positron production rates with the use of calorimeters and beam diagnostics with tracking detectors, this experiment is strongly bound to accelerator and beam physics. This paper reviews the principles of the experiment and the details necessary to provide a solid ground for the beam-dynamics uncertainties and the corrections of the systematic effects influencing the output of the experiment: a single numerical value, which may unveil new physics.

43 PARTICLE ACCELERATORS↗

Molten Salt Reactor Experiment Benchmark Evaluation

As one of the six advanced reactor concepts selected by the 2002 Generation IV roadmap as a technology meriting future research, Molten Salt Reactors (MSRs) attracted broad attention and multiple private and public entities are working towards its commercialization. Facing stringent regulatory requirements, validations of computational codes used to calculate and prove the safety characteristics of MSRs play a key role. This project developed the world-first, MSR-related reactor physics benchmark based on a series of zero-power experiments conducted at the Molten Salt Reactor Experiment (MSRE). The benchmark was successfully reviewed by the International Reactor Physics Experiment Evaluation Project (IRPhEP) committee and is available in the IRPhEP handbook starting form the 2019 edition. To benchmark experimental data from the MSRE, a three-dimensional high-fidelity model was developed using the Monte Carlo neutron transport code Serpent 2 and ad-hoc methods have been implemented to account for the unique feature of fuel salt motion. The calculated effective multiplication factor, k eff , for the first criticality experiment, when 235 U was progressively added to the fuel salt in order to achieve criticality with stationary salt and isothermal conditions, was 1.02132 (±3 pcm). The total uncertainty for experimental k eff was estimated to be 420 pcm. The calculated k eff is 2.154% larger than the experimental and benchmark model value, which is approximately five times the benchmark model uncertainty. It is to be noted that, for systems containing large volume of graphite (or other carbonaceous materials), Monte Carlo codes tend to overestimate the keff of the benchmark model by 1% to 2%. The bias is possibly due to uncertainties in the impurity content of the graphite blocks, uncertainty in the neutron capture cross section of carbon or uncertainty in the properties of nuclear-grade graphite. The calculated reactivity coefficient of 235 U concentration (0.2228 ± 0.0014, represented as the change of reactivity over the relative change of 235 U mass in loop) matches well with the experimental value (0.223 ± 0.006), strengthening the confidence on the accurate representation of the fuel salt composition in the MSRE benchmark. Additional reactivity effect calculations, including the control rod bank worth, reactivity effects of fuel circulation and isothermal and fuel temperature coefficients show good agreement with the experimental values (within 1σ) as well.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

The Mu2e Experiment (Final Technical Report)

This is the final technical report for the initial two year funding period to start a new collaboration group at the University of California Davis for the Mu2e Experiment at Fermilab. The goal if the Mu2e Experiment is to search for the conversion to an electron of a muon that has been captured by an aluminum nucleus. While this process is effectively forbidden in the Standard Model, it is a virtually universal feature of models beyond the Standard Model. Mu2e will probe the reaction with a sensitivity that is roughly four orders of magnitude better than the best previous measurement. This range of sensitivity probes most of the parameters space of supersymmetry, and any signal will be unambigious proof of physics beyond the Standard Model. Professor Prebys was one of the founding members and first spokespersons of the Mu2e Experiment during his time af Fermilab. He came to UC Davis in 2017 with the goal of starting a Mu2e collaborating group here, and this grant has funded that effort. Specifically, in addition to summer salary, it has supported a graduate student and a postdoc, both of whom are now permanently stationed at Fermilab. During this time, their work has focused primarily on the understanding to the formation of the proton bunches in Fermilab Recycler, as this is critical to the experiment. This has included both measurements and simulations.

43 PARTICLE ACCELERATORS↗

Understanding Critical Systematics on Neutrino Oscillation Experiments from Neutrino-Nucleus Interactions. Final report

This is a final report on the DOE grant DE-SC0017946: Understanding Critical Systematics on Neutrino Oscillation Experiments from Neutrino-Nucleus Interactions. The goal of this proposal was to better understand the complex many-body dynamics of neutrino-nucleus interactions in order to control the systematic uncertainties that will dominate current and future long-baseline neutrino experiments. This work was focused on a new and experimentally challenging aspect of the problem: measuring the abundance and kinematics of final state nucleons. The research leveraged two different detectors and beam energies: the Near Detector (ND) of the NOvA Experiment, off-axis on the NuMI beam- line, and the Accelerator Neutrino Neutron Interaction Experiment (ANNIE), on the Booster Neutrino Beam (BNB). The techniques developed will also help reject the dominant neutrino-induced backgrounds limiting future proton decay searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Heavily Confined PBX 9501 Experiment Report FY2020

Most accidental insults to explosives are invariably thermal in nature—either direct thermal via application of heat or indirect thermal when mechanical energy is converted to heat. The key question is whether the initial thermal insult transitions into a violent explosive response. If the ultimate violence attained is moderate, nearby personnel may be harmed or killed, but Inadvertent Nuclear Detonation (IND) will not occur. However, if the explosive ultimately transitions from deflagration to detonation (DDT) then IND becomes a concern. PBX 9501 is not an insensitive high explosive (IHE). It has been conclusively demonstrated that mechanically and thermally damaged PBX 9501 can readily DDT in heavy confinement. However, it is currently unknown whether pristine explosive—i.e. thermally and mechanically undamaged— is capable of DDT. Three experiments were conducted in order to determine whether very heavily confined pristine PBX 9501 is capable of DDT. All experiments used identical 6-inch diameter spherical charges of PBX 9501 confined in a 350 lb. hardened steel vessel with >2.5-inch thick walls. The first, primary experiment tested pristine PBX 9501 and was thermally ignited at the center of using a laser over optical fiber. Two additional baseline experiments were performed for comparison: the second test was initiated at the center using a detonator; the third test was bulk heated until self-ignition (cookoff). Velocimetry data in combination with hydrocode simulations suggest that a classical detonation wave did not develop in the pristine, thermally ignited PBX 9501. Reaction violence was approximately equivalent—in terms of ultimate energy output—as a full detonation, but the acceleration of metal fragments occurred more slowly than in a detonation-driven scenario.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Modifications to the Bubble experiment and preparation for additional irradiations

SHINE Medical Technologies is planning to use neutron-induced fission in a subcritical low-enriched-uranium uranyl sulfate target solution for production of 99 Mo. During this operation, the solution will undergo self-heating due to fissioning of the uranium, radiolytic decomposition of the water, and circulation due to thermal gradients generated in the solution, and will be cooled by cooling tubes running through the annulus and from cooling outside the annulus. Because the formation of the radiolysis-induced bubbles (H 2 and O 2 ) and their size and dynamics will impact the operational parameters of the liquid target, an understanding of bubble behavior is critical for the ability to predict the behavior of the target solution during this operation. It is also important to be able to predict the thermal gradients and the circulation in the vessel. Researchers at Argonne National Laboratory have designed an experimental setup to study radiolytic gas formation in uranyl sulfate under direct electron beam irradiation and have conducted initial experiments. Results of those experiments provided invaluable information on thermal hydraulic behavior of the solution and some information on bubble formation and behavior, but those initial experiments fell short in the measurements of the gas generation rates and bubble behavior. To address the shortcomings of the original experiment, the irradiation setup was modified to improve our abilities to measure gas generation rates and measure the temperature distribution in the solution with better precision. Modifications to the experimental setup and preparation for the irradiations are described below.

07 ISOTOPE AND RADIATION SOURCES↗

Evaluation of Structural Lattices for a Davis Gun Earth Penetrator Impact Experiment

The advanced materials team investigated the use of additively manufactured metallic lattice structures for mitigating impact response in a Davis gun earth penetrator impact experiment. High-fidelity finite element models were developed and validated with quasistatic experiments. These models were then used to simulate the response of such lattices when subjected to the acceleration loads expected in the Davis gun experiment. Results reveal how the impact mitigation performance of lattices can change drastically at a certain relative density. Based on these observations, an experiment deck was designed to probe the response of lattices with different relative densities during the Davis gun phase 2 shots. The expected performance of these lattices is predicted before testing based on simulation results. The results of the Davis gun phase 2 shots are expected to provide data which will be used to assess the predictive capability of the finite element simulations in such a complex impact environment.

36 MATERIALS SCIENCE↗

The Forward Physics Facility: Sites, Experiments, and Physics Potential

The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF; the FPF experiments currently envisioned to realize the FPF’s physics potential; and the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

A New Data Analysis Technique for Determining Mix Parameters from HED Experiments

In designing, analyzing, and understanding high-energy-density (HED) physics experiments, including inertial confinement fusion (ICF) experiments, we must contend with the extension of hydrodynamics to new regimes where additional physics, such as radiation transport and nuclear reactions, become important and coupled to the dynamics. Our most sophisticated models and understanding are based in classical, low-energy physics, since that is what we have the easiest access to creating and diagnosing. To assess our extrapolation of that understanding to the HED regime will require comparable precision in experiments and measurements. This is particularly the important in the case of hydrodynamic turbulence — most experiments are designed with one or two dimensions of symmetry, but at small scales hydrodynamics is generically observed to crumple into a fine structure of apparently random, three-dimensional eddies.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Project Description for Student Symposium 2022: Modeling Approach to Critical in the Upcoming CERBERUS Experiment

The Critical Experiment Reflected By copper to BettEr Understand Scattering [CERBERUS] is an integral experiment that will be executed at the end of FY23. The experiment is designed to study the intermediate energy range, in particular elastic and inelastic scattering of neutrons in copper. Approaching criticality safely is of utmost importance, and having a computer mode is a useful tool when determining changes that can safely be made to the experiment. Multiple simulations are needed to analyze the approach to critical, and manually creating MCNP input files is both tedious and error prone. To solve this problem, a python script was created to develop and run these input files.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

IER 296 Experiment- Thermal Feasibility Analysis [Slides]

This set of slides summarizes progress, highlights, and issues related to the LANL design engineering effort for the IER 296 critical experiment. The experiment configuration described in Section 5.1.1 of CED-1 IRSN Preliminary Design for Thermal/Epithermal Experiments with MOX FUEL (TEX-MOX) is re-examined in a finite element analysis model using design geometry utilized in the Chlorine Worth Study (CWS) Experiments. Preliminary results and design considerations are presented. Additional analysis has been performed based on comments from the collaborative virtual meeting on 12JAN2023. Specifically, the fuel cladding and gas gap have been included in the thermal analysis.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

PROSPECT: A Precision Reactor Oscillation and Spectrum Experiment

Nuclear reactors are a source of copious amounts of electron antineutrinos. They are emitted in the beta decays of the fission products and their energies depend on the isotopic composition of the reactor. In recent years a number of reactor antineutrino experiments including Daya Bay, Double Chooz, and RENO reported a deficit in the measured flux of antineutrinos from reactors compared to expectation and a spectral deviation in the measured energy spectra compared to model predictions. These observations led to the hypothesis of sterile neutrino oscillation as an explanation of the flux deficit. New physics or incomplete nuclear models may explain the origin of the spectral deviation. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, is a novel neutrino experiment at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) designed to address two major scientific objectives: 1. Perform a search for eV-scale sterile neutrinos independent of reactor neutrino models by searching for the oscillation signature of massive, sterile neutrino states beyond the 3 known active neutrino species. The discovery of sterile neutrinos would indicate a new form of matter and require physics beyond the Standard Model. 2. Perform the first modern precision measurement of the antineutrino spectrum from a Highly Enriched Uranium (HEU) 235 U reactor to benchmark our understanding of the neutrino emission from nuclear reactors and to understand the isotopic origin of spectral deviations observed in previous reactor neutrino experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

The JLab Eta Factory (JEF) experiment

The new experiment, JLab Eta Factory (JEF), in the experimental Hall D at Jefferson Lab will extend the physics potential of the GlueX detector beyond the main spectroscopy program and perform precision measurements of various ?(?)decays with emphasis on rare neutral modes. The physics program of the experiment spans from precision tests of low-energy QCD to search of gauge bosons in the mass range below 1 GeV coupling the SM sector to the dark sector. Photoproduction of highly boosted ?(?)mesons using a tagged photon beam, good detection of recoil proton and multi-photon final states will allow to suppress background and collect high-statistics data sample of ?mesons. All these provide many advantages over other ?(?)experiments. The JEF experiment requires to upgrade the inner part of the forward lead glass calorimeter of the GlueX detector with high-granularity, high-resolution lead tungstate PbWO4 scintillating crystals. The calorimeter insert is currently under construction at Jeffeson Lab. The detector will be ready to take data in 2024. An overview of the JEF project will be presented.

Somov, Alexander↗

Evaluation of a streaming readout solution for Jefferson Lab experiments

Jefferson Lab (JLab) operates the CEBAF accelerator that provides a high energy (up to 12 GeV) and high current (up to 150 µA) polarized electron beam for fixed target experiments. JLab's mission is to provide substantial progress in understanding the Quantum Chromo Dynamics (QCD), the current theory of the spectrum and the dynamics of hadronic matter. Given the broad scientific program a general-purpose detector, CLAS12, has been designed and constructed. Such a detector requires a sophisticated trigger and current experiments use an on-line FPGA-based system that relies upon custom firmware and electronics both of which are difficult reconfigure from one experiment to the next. To overcome these challenges transitioning to a streaming readout has been proposed since it would allow a more flexible, easier to debug, software trigger to be developed. To facilitate this JLab is gaining experience with streaming readout systems and is actively working to design and test a streaming data acquisition architecture. Significant work has already been done to make existing front-end electronics compatible with operation in streaming mode. Software-wise, much work remains to be done but an existing framework, TriDAS, which was developed for underwater neutrino telescopes can, in principle, be used with the existing JLab hardware. A test stand is already in place in the INDRA DAQ development lab at JLab. This paper will present the development of this TriDAS based test system and it?s operation in-beam using parts of the CLAS12 detector to evaluate streaming readout for a large general purpose detector.

Battaglieri, Marco↗

The Mu2e Experiment at Fermilab

The Muon-to-Electron-Conversion (Mu2e) Experiment is a high-precision, intensity-frontier experiment being developed at Fermilab that will search for coherent, neutrino-less muon to electron conversion in the presence of an atomic nucleus. Such a process would exhibit charged lepton flavor violation (CLFV), which has not yet been observed. Continuing the search for CLFV, Mu2e will improve the sensitivity by four orders of magnitude over the present limits. In the search for beyond the standard model (BSM) physics, Mu2e is uniquely sensitive to a wide range of models by indirectly probing mass scales up to the energy scale of 10^4 TeV. While muon-to-electron-conversion is permissible in an extension of the standard model through neutrino oscillations, the rate is extremely low at about one event in 10^52. By design, the background for the experiment will be well-understood and kept at a sub-event level, which will mean the observation of muon-to-electron conversion is a dire ct confirmation of BSM physics. The physics motivation, the design, and the current status of the experiment will be presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

INL Report: Multiphysics Modeling and Simulation of Deimos, an Advanced Reactor Experiment

When designing a novel reactor, nuclear experiments are essential to validate the predictive capability of modeling/simulation tools and to justify the investment of a full-scale prototype. Being able to accurately predict temperature reactivity coefficients is of high importance to reactor designers as it impacts the safety and performance of the system. Deimos is a proposed graphite-moderated, beryllium-reflected, high assay low-enriched uranium (HALEU) tri-structural isotropic (TRISO) fueled experiment for NCERC. Deimos is a valuable experiment for validating the predictive performance of modeling and simulation tools since it comprises a relatively thermal energy spectrum with 84% thermal neutrons causing fission, 15% epithermal neutrons causing fission, and 1% fast neutrons causing fission. Additionally, by electrically heating the experiment, reactivity can be validated at various temperatures. Deimos will serve as a testbed for future advanced reactor concepts.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗