15 Search Results

Irradiation experiment campaigns are critical to advancing nuclear energy technologies by providing data on material performance under relevant radiation conditions. Successful irradiation experiments require integrated design efforts that balance technical goals with facility constraints. Here, this paper presents an expert-informed overview of irradiation experiment design at the High Flux Isotope Reactor. It addresses the nuclear materials research and irradiation experiment communities to guide them toward developing technically sound, facility-compatible campaigns. The High Flux Isotope Reactor is a multipurpose reactor supporting isotope production, neutron scattering, and materials testing. Its high, steady-state neutron flux is ideal for irradiation experiments, but successful executionmore » demands coordinated thermal, structural, and reactor physics analyses. The paper outlines the complete development workflow from concept definition and design optimization to safety qualification and post-irradiation examination. Standardized capsule platforms are also discussed in terms of flexibility, specimen capacity, and thermal performance. Common failure modes such as unanticipated geometric variations, can impact temperature-dose profiles and compromise data reliability. Therefore, detailed thermal modeling and accurate as-built characterization are essential for meaningful post-irradiation data interpretation. Key recommendations include early engagement all stakeholders, clearly defined design expectations, and alignment of specimen geometries with post-irradiation examination capabilities. This approach reduces design iterations, enhances data quality, and supports more efficient use of irradiation resources. Strategic and well-planned irradiation testing not only improves individual campaign success but also accelerates the deployment of advanced nuclear technologies. By closing critical data gaps and reducing development risks, the nuclear materials community can more effectively contribute to the future of clean, resilient energy systems.« less

Enhanced Geothermal Systems (EGS) are a promising concept for unlocking the great potential of Hot Dry Rock (HDR) for sustainable clean-energy production. However, EGS has remained an elusive goal due to the unsolved challenges of induced seismicity, uneconomically low flow rates, and premature cooling of the produced fluid. We propose that fracture caging offers a path to solving these three challenges. Fracture caging is the placement of a cage of boundary wells around injection wells before injection begins. This cage captures injected fluid to halt fracture growth, even if injection continues at the high-pressures that are conventionally used only formore » hydraulic fracture stimulation. This pressure will hydroprop fractures to achieve the flowrates that are required for EGS, instead of relying on proppant or shear stimulation. In this study, we present laboratory experiments and a conceptual model to explore the physical limits of hydraulic fracture caging. More specifically we investigate the required number of wells, maximum flow rates, and boundary conditions needed to unlock caging and hydropropping as tools to achieve viable geothermal systems.« less

Accurate predictions of fuel spray behavior and mixture formation in simulations of direct-injection spark-ignition (DISI) engines are fundamental to ensure proper description of all subsequent processes including ignition, combustion, and emissions. In this work, the spray evolution in a single-cylinder optical DISI engine was studied experimentally and numerically with the goal of enabling predictive computational fluid dynamics (CFD) modeling of in-cylinder sprays. The authors explored a wide range of operating conditions characterized by several fuel injection temperatures and engine speeds, using a well-characterized nine-component gasoline surrogate known as PACE-20. The effect of flash boiling and intake crossflow on the spraymore » is discussed, with a focus on evaluating the ability of the spray models to capture highly transient spray behavior. In the experiments, the fuel temperature was varied between 20°C and 80°C, allowing for non-flash- to flash-boiling transition to emerge with enhanced flashing intensity at the highest temperatures. Spray collapse resulted in vapor-rich regions, owing to the locally lower inertia of the fluid. Varying the engine speed from 650 to 1950 rpm promoted increasingly more turbulent in-cylinder crossflow which interacted with the spray during the injection event and resulted in enhanced spray dispersion. The CFD model was able to capture the spray morphology transition at different fuel temperatures and engine speeds adequately. Further, it is shown that the spray breakup model could capture the transitional spray behavior induced by flash boiling atomization and intake flow via proper initialization of the spray cone angle and calibration of the spray models’ constants.« less

We measure the cross section of e⁺e^- → ηcJ/ψ at the Υ(nS)(n = 1–5) on-resonance and 10.52 GeV off-resonance energy points using the full data sample collected by the Belle detector with an integrated luminosity of 955 fb^-1. We also search for double charmonium production in e⁺e^- → ηcJ/ψ via initial state radiation near the ηcJ/ψ threshold. No evident signal of the double charmonium state is found, but evidence for the e⁺e^- → ηcJ/ψ process is found with a statistical significance greater than 3.3σ near the ηcJ/ψ threshold. The average cross section near the threshold is measured and upper limitsmore » of cross sections are set for other regions.« less

Dynamic stall has been a technical challenge and a fluid dynamical subject of interest for more than fifty years; but in the last decade significant advances have been made in the understanding, prediction, modeling, and control of dynamic stall on rotors. This paper provides a summary of the state of the art of dynamic stall experiments and future directions in the understanding of dynamic stall on rotors. Experimental data sets are discussed, as well the direction of future research for control of dynamic stall. Coordinated testing between airfoils and rotating blades, as well as close integration between computational and experimentalmore » studies were found to be productive approaches. Advanced analysis methods, including statistical methods, modal representations, and artificial intelligence methods have led to significant advances in the understanding of dynamic stall. Investigations of dynamic stall control devices have allowed many useful targeted investigations of the transition to separated flow, but have not yet resulted in a commercially implemented device.« less

Using data samples with an integrated luminosity of 19 fb^-1 at twenty-eight center-of-mass energies from 3.872 GeV to 4.700 GeV collected with the BESIII detector at the BEPCII electron-positron collider, the process e⁺e^- → ηπ⁺π^- and the intermediate process e⁺e^- → ηρ⁰ are studied for the first time. The Born cross sections are measured. No significant resonance structure is observed in the cross section lineshape.

Based on e⁺e^- collision samples corresponding to an integrated luminosity of 4.4 fb^-1 collected with the BESIII detector at center-of-mass energies between 4.6 GeV and 4.7 GeV, a partial wave analysis of the charmed baryon hadronic decay $${\Lambda}_c^{+}$$ → Λπ⁺π⁰ is performed, and the decays $${\Lambda}_c^{+}$$ → Λρ(770)⁺ and $${\Lambda}_c^{+}$$ → Σ(1385)π are studied for the first time. Making use of the world-average branching fraction $$\mathcal{B}$$ ($${\Lambda}_c^{+}$$ → Λπ⁺π⁰), their branching fractions are determined to be $$\mathcal{B}$$($${\Lambda}_c^{+}$$ → Λρ(770)⁺) = (4.06 ± 0.30 ± 0.35 ± 0.23) x 10^-2, $$\mathcal{B}$$($${\Lambda}_c^{+}$$ → Σ(1385)⁺)π⁰) = (5.86 ± 0.49 ± 0.52 ± 0.35)more » x 10^-3, $$\mathcal{B}$$($${\Lambda}_c^{+}$$ → Σ(1385)⁰)π⁺) = (6.47 ± 0.59 ± 0.66 ± 0.38) x 10^-3, where the first uncertainties are statistical, the second are systematic, and the third are from the uncertainties of the branching fractions $$\mathcal{B}$$ $${\Lambda}_c^{+}$$ → Λπ⁺π⁰ and $$\mathcal{B}$$(Σ(1385) → Λπ). In addition, the decay asymmetry parameters are measured to be _αΛρ(770)+ = - 0.763 ± 0.053 ± 0.045, $$\alpha$$_{Σ(1385)+π⁰} = -0.917 ± 0.069 ± 0.056, and $$\alpha$$_{Σ(1385)⁰π⁺} = -0.789 ± 0.098 ± 0.056.« less

Using (448.1 ± 2.9) × 10⁶ ψ(3686) events collected with the BESIII detector at the BEPCII collider, the decay ψ(3686) → Σ^-$$\overline{Σ}$$⁺ is observed for the first time with a branching fraction of (2.82 ± 0.04_stat. ± 0.08_syst.) × 10^-4, and the angular parameter α_Σ- is measured to be 0.96 ± 0.09_stat. ± 0.03_syst..

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 progressmore » in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF’s physics potential. We then review 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.« less

Proton exchange membrane fuel cells (PEMFC) with cathodes using platinum group metal-free (PGM-free) catalysts could significantly reduce costs, but the lower volumetric oxygen reduction reaction (ORR) activity requires thick electrodes that suffer from liquid water flooding and increased oxygen transport resistance. To address these challenges, we developed a 3D gas diffusion electrode (GDE) architecture to enhance liquid water removal through the diffusion media and reduce cathode saturation. The cathode features a uniform catalyst layer adjacent to the membrane for high ORR activity and then pillars of the hydrophilic catalyst layer that pass through the microporous layer (MPL), providing a lowmore » capillary pressure barrier pathway to the carbon fiber paper layer and channel. The non-planar cathode also increases the interfacial area between the catalyst layer and hydrophobic MPL for a greater fraction of the cathode with high O₂ concentration. Our studies included parametric experimental study of the pillar density to identify the optimum pitch between pillars. Our measurements show significant improvements in the mass transport region of the polarization curve with 3D structured electrodes leading to an 8% increase in maximum current density, 19% increase in maximum power density, and 16% increase in current density at 0.67 V with air.« less