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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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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Exclusive four pion photoproduction in ultraperipheral Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

The intense photon fluxes from relativistic nuclei provide an opportunity to study photonuclear interactions in ultraperipheral collisions. The measurement of coherently photoproduced π + π − π + π − final states in ultraperipheral Pb–Pb collisions at √s NN = 5.02 TeV is presented for the first time. The cross section, dσ/dy, times the branching ratio (ρ →π + π + π − π − ) is found to be 47.8±2.3 (stat.)± 7.7 (syst.) mb in the rapidity interval |y| < 0.5. The invariant mass distribution is not well described with a single Breit-Wigner resonance. The production of two interfering resonances, ρ(1450) and ρ(1700), provides a good description of the data. The values of the masses (m) and widths (Γ) of the resonances extracted from the fit are m 1 = 1385±14 (stat.)±3 (syst.) MeV/c 2 , Γ 1 = 431±36 (stat.)±82 (syst.) MeV/c 2 , m 2 = 1663±13 (stat.)±22 (syst.) MeV/c 2 and Γ 2 = 357 ± 31 (stat.)±49 (syst.) MeV/c 2 , respectively. The measured cross sections times the branching ratios are compared to recent theoretical predictions.

FOS: Physical sciences↗
DOE OSTI2025

Diffractive Physics Program at the Electron–Ion Collider’s (EIC) 2 nd Detector

The Electron–Ion Collider (EIC) will be a novel experimental facility to explore the properties of gluons in nucleons and nuclei, shedding light on their structure and dynamics. The EIC community outlined the physics program of the EIC in a White Paper, and the demanding detector re quirements and potential technologies to deploy at an EIC detector were published in a comprehensive Yellow Report. The general-purpose detector resulting from these efforts, ePIC, is designed to perform a broad physics program. At the same time, the wider EIC community is strongly in favor of a second detector at the EIC. Having two general-purpose collider detec tors to support the EIC science program allows us to have cross-checks and control of systematic uncertainties for potential scientific discoveries. The second detector should feature complementary technologies where possible. It can also focus on specific measurements that are less well-addressed by ePIC. The second interaction region provides potentially improved forward detector acceptance at low pT and a secondary beam focus that enables to enhance the exclusive, tagging, and diffractive physics program. Hereby, I will present the potential capabilities of the second detector and discuss studies related to its diffractive physics program.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

QCD Results from the Tevatron

We present results from soft and hard QCD studies at the Tevatron. The recent study of central exclusive $π^+ π^-$ production at $\sqrt{s} =$ 900 and 1960 GeV is discussed, as well as results on multi-parton interaction (MPI) for different final states, including final states consisting of heavy flavor mesons, $J/ψ$ and/or $\Upsilon$. Finally, the measurement of $Z → bb$ jets is presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

The BDX experiment at Jefferson Laboratory

The Beam Dump Experiment (BDX) at Jefferson Laboratory (JLab) is an electron-beam thick-target experiment to search for Light Dark Matter (LDM) particles in the MeV-GeV mass range. BDX will exploit the high-intensity 10.6 GeV e^-e ? beam from CEBAF accelerator impinging on the beam dump of experimental Hall-A, collecting up to 10^{22}10 22 electrons-on-target (EOT) in a few years time. Any LDM particle produced by the interaction of the primary e^-e ? beam with the beam dump will be detected by measuring their scattering inside the BDX detector, an electromagnetic calorimeter surrounded by an hermetic veto system, which is to be installed in a dedicated underground facility, located 20 m downstream. Thanks to the large detection efficiency and background rejection capabilities, BDX will be able to explore a so-far unknown region in the LDM parameter space, improving current exclusion limits by one order of magnitude in case of a null observation. In preparation to the full experiment, a small-scale version called BDX-MINI, has been built and operated at JLab with a lower energy beam. Despite the small interaction volume, the large accumulated charge of 2.2\times10^{21}2.2×10 21 EOT allowed for the BDX-MINI measurement to set competitive exclusion limits on the LDM parameters space, comparable to those reported by larger-scale efforts.

Celentano, A.↗
DOE OSTI2018

Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks

Formation of condensed matter typically involves a trade-off between structural order and flexibility. As the extent and directionality of interactions between atomic or molecular components increase, materials generally become more ordered but less compliant and vice versa. Yet, high levels of structural order and flexibility need not necessarily be mutually exclusive: there are many biological (e.g., microtubules, flagella, viruses) and synthetic assemblies (e.g., dynamic molecular crystals and frameworks) that can undergo considerable structural transformations without losing their crystalline order and possess remarkable mechanical properties with utility in diverse applications such as selective sorption, separation, sensing, and mechanoactuation. Ultimately, however, the extent of structural changes by such flexible crystals and their elasticity are constrained by the necessity to maintain a continuous network of bonding interactions between the constituents of the lattice. Consequently, even the most dynamic porous materials tend to be brittle and isolated as microcrystalline powders,14 and flexible organic/inorganic molecular crystals cannot expand without fracturing. Owing to their rigidity, crystalline materials rarely display self-healing behavior. Here we report that macromolecular ferritin crystals with integrated hydrogel polymers can isotropically expand to 180% of their original dimensions and >500% of their original volume while retaining periodic order and faceted Wulff morphologies. Even after the separation of neighboring ferritin molecules by 50 Å upon lattice expansion, specific molecular contacts between them can be reformed upon lattice contraction, resulting in the recovery of atomic-level periodicity and the highest resolution ferritin structure reported. Dynamic bonding interactions between the hydrogel network and the ferritin molecules endow the crystals with the ability to resist fragmentation and self-heal efficiently, while the chemical tailorability of the ferritin molecules enables the creation of chemically and mechanically differentiated domains within single crystals.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Highly Active and Stable Single Atom Rh 1 /CeO 2 Catalyst for CO Oxidation during Redox Cycling

We report a single atom Rh 1 /CeO 2 catalyst prepared by the high temperature (800 °C) atom trapping (AT) method which is stable under both oxidative and reductive conditions. Infrared spectroscopic and electron microscopy characterization revealed the presence of exclusively ionic Rh species. These ionic Rh species are stable even under reducing conditions (CO at 300 °C) due to the strong interaction between Rh and CeO 2 achieved by the AT method, leading to high and reproducible CO oxidation activity regardless of whether the catalyst is reduced or oxidized. In contrast, ionic Rh species in catalysts synthesized by a conventional impregnation approach (e. g., calcined at 350 °C) can be readily reduced to form Rh nanoclusters/nanoparticles, which are easily oxidized under oxidative conditions, leading to loss of catalytic performance. The single atom Rh 1 /CeO 2 catalysts synthesized by the AT method do not exhibit changes during redox cycling hence are promising catalysts for emission control where redox cycling is encountered, and severe oxidation (fuel cut) leads to loss of performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

A structural explanation for the mechanism and specificity of plant branching enzymes I and IIb

Branching enzymes (BEs) are essential in the biosynthesis of starch and glycogen and play critical roles in determining the fine structure of these polymers. The substrates of these BEs are long carbohydrate chains that interact with these enzymes via multiple binding sites on the enzyme’s surface. By controlling the branched-chain length distribution, BEs can mediate the physiological properties of starch and glycogen moieties; however, the mechanism and structural determinants of this specificity remain mysterious. In this study, we identify a large dodecaose binding surface on rice BE I (BEI) that reaches from the outside of the active site to the active site of the enzyme. Mutagenesis activity assays confirm the importance of this binding site in enzyme catalysis, from which we conclude that it is likely the acceptor chain binding site. Comparison of the structures of BE from Cyanothece and BE1 from rice allowed us to model the location of the donor-binding site. We also identified two loops that likely interact with the donor chain and whose sequences diverge between plant BE1, which tends to transfer longer chains, and BEIIb, which transfers exclusively much shorter chains. When the sequences of these loops were swapped with the BEIIb sequence, rice BE1 also became a short-chain transferring enzyme, demonstrating the key role these loops play in specificity. Taken together, these results provide a more complete picture of the structure, selectivity, and activity of BEs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Electron and neutrino scattering off the deuteron in a relativistic framework

Here, we build a relativistic model to perform calculations of exclusive, semiexclusive, and inclusive unpolarized cross sections and various polarization observables in electron and neutrino scattering experiments with deuteron targets. The strong interaction dynamics is defined by an explicit dynamical unitary representation of the Poincaré group, where representations of space translations and rotations in the interacting and noninteracting representations are the same. The Argonne V18 potential is used to construct a relativistic nucleon-nucleon interaction reproducing the experimental deuteron binding energy and nucleon-nucleon scattering observables. Our formalism does not include the pion production channel and neglects two-body contributions in the electromagnetic as well as in the weak nuclear current operator. We show that it is applicable to processes at kinematics, where the internal two-nucleon energy remains below the pion production threshold but the magnitude of the three-momentum transfer extends at least to several GeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Realizability-preserving DG-IMEX method for the two-moment model of fermion transport

Building on the framework of Zhang & Shu [1], [2], we develop a realizability-preserving method to simulate the transport of particles (fermions) through a background material using a two-moment model that evolves the angular moments of a phase space distribution function f . The two-moment model is closed using algebraic moment closures; e.g., as proposed by Cernohorsky & Bludman [3] and Banach & Larecki [4]. Variations of this model have recently been used to simulate neutrino transport in nuclear astrophysics applications, including core-collapse supernovae and compact binary mergers. We employ the discontinuous Galerkin (DG) method for spatial discretization (in part to capture the asymptotic diffusion limit of the model) combined with implicit-explicit (IMEX) time integration to stably bypass short timescales induced by frequent interactions between particles and the background. Appropriate care is taken to ensure the method preserves strict algebraic bounds on the evolved moments (particle density and flux) as dictated by Pauli's exclusion principle, which demands a bounded distribution function (i.e., f ϵ [0,1]). This realizability-preserving scheme combines a suitable CFL condition, a realizability-enforcing limiter, a closure procedure based on Fermi-Dirac statistics, and an IMEX scheme whose stages can be written as a convex combination of forward Euler steps combined with a backward Euler step. The IMEX scheme is formally only first-order accurate, but works well in the diffusion limit, and — without interactions with the background — reduces to the optimal second-order strong stability-preserving explicit Runge-Kutta scheme of Shu & Osher [5]. Numerical results demonstrate the realizability-preserving properties of the scheme. As a result, we also demonstrate that the use of algebraic moment closures not based on Fermi-Dirac statistics can lead to unphysical moments in the context of fermion transport.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Constraining the Self-Interacting Neutrino Interpretation of the Hubble Tension

Large, nonstandard neutrino self-interactions have been shown to resolve the ~4σ tension in Hubble constant measurements and a milder tension in the amplitude of matter fluctuations. Herein we demonstrate that interactions of the necessary size imply the existence of a force carrier with a large neutrino coupling (>10 -4 ) and mass in the keV–100 MeV range. This mediator is subject to stringent cosmological and laboratory bounds, and we find that nearly all realizations of such a particle are excluded by existing data unless it carries spin 0 and couples almost exclusively to $τ$-flavored neutrinos. Furthermore, we find that the light neutrinos must be Majorana particles, and that a UV-complete model requires a nonminimal mechanism to simultaneously generate neutrino masses and appreciable self-interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

World Whaling: Historical and Contemporary Studies

Whales are omnipresent in the consciousness of modern society, but their public and scientific perceptions have significantly shifted over the last several hundred years. Today, there is a broad attempt to protect and study whales and their habitats, even while sustainable commercial and Indigenous fisheries continue. For the past several millennia humans have interacted with and exploited whales – but it is the critical period since ca. ~1700 that dominates our public understanding of these animals primarily due to their extreme over-exploitation during this era. Further, the dichotomy between protecting whales versus exploiting whales is real, not always mutually exclusive, and palpably stressful both within society and within this text. That is one reason why this Senri Ethnological Studies volume edited by Nobuhiro Kishigami is such a significant contribution to the whale literature, especially for those interested in the state of modern humanwhale interaction and the historical processes that led to the current structure of whale science, protection, regulation and exploitative fisheries.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Strong QCD Insights from Excited Nucleon Structure Studies with CLAS and CLAS12

Studies of the spectrum of hadrons and their structure in experiments with electromagnetic probes offer unique insight into many facets of the strong interaction in the regime of large quark-gluon running coupling, i.e. the regime of strong QCD. The experimental program within Hall B at Jefferson Laboratory based on data acquired with the CLAS spectrometer using electron and photon beams with energies up to 6 GeV has already considerably extended the scope of research in hadron physics in joint efforts between experiment and phenomenological data analysis. Impressive progress in relating the hadron structure observables inferred from the data to the strong QCD mechanisms underlying hadron mass generation has been achieved in the past decade. Furthermore, these results will be considerably extended with data from the experimental program with the new CLAS12 spectrometer that has begun data taking using electron beams with energies up to 11 GeV. With this extended kinematic reach the structure of nucleon resonances will be probed at the highest photon virtualities ever achieved in the studies of exclusive electroproduction, which will allow for the exploration of the distance scale where>98% of light hadron mass emerges from QCD in the transition of the strong interaction from the regime of quark-gluon confinement to perturbative QCD.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Interactive contour delineation of organs at risk in radiotherapy: Clinical evaluation on NSCLC patients

Purpose: Accurate delineation of organs at risk (OARs) on computed tomography (CT) image is required for radiation treatment planning (RTP). Manual delineation of OARs being time consuming and prone to high interobserver variability, many (semi-) automatic methods have been proposed. However, most of them are specific to a particular OAR. Here, an interactive computer-assisted system able to segment various OARs required for thoracic radiation therapy is introduced. Methods: Segmentation information (foreground and background seeds) is interactively added by the user in any of the three main orthogonal views of the CT volume and is subsequently propagated within the whole volume. The proposed method is based on the combination of watershed transformation and graph-cuts algorithm, which is used as a powerful optimization technique to minimize the energy function. The OARs considered for thoracic radiation therapy are the lungs, spinal cord, trachea, proximal bronchus tree, heart, and esophagus. The method was evaluated on multivendor CT datasets of 30 patients. Two radiation oncologists participated in the study and manual delineations from the original RTP were used as ground truth for evaluation. Results: Delineation of the OARs obtained with the minimally interactive approach was approved to be usable for RTP in nearly 90% of the cases, excluding the esophagus, which segmentation was mostly rejected, thus leading to a gain of time ranging from 50% to 80% in RTP. Considering exclusively accepted cases, overall OARs, a Dice similarity coefficient higher than 0.7 and a Hausdorff distance below 10 mm with respect to the ground truth were achieved. In addition, the interobserver analysis did not highlight any statistically significant difference, at the exception of the segmentation of the heart, in terms of Hausdorff distance and volume difference. Conclusions: An interactive, accurate, fast, and easy-to-use computer-assisted system able to segment various OARs required for thoracic radiation therapy has been presented and clinically evaluated. The introduction of the proposed system in clinical routine may offer valuable new option to radiation oncologists in performing RTP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

First measurement of the Ti ( e , e ' ) X cross section at Jefferson Lab

To probe CP violation in the leptonic sector using GeV energy neutrino beams in current and future experiments using argon detectors, precise models of the complex underlying neutrino and antineutrino interactions are needed. The E12-14-012 experiment at Jefferson Lab Hall A was designed to perform a combined analysis of inclusive and exclusive electron scatterings on both argon (N = 22) and titanium (Z = 22) nuclei using GeV-energy electron beams. The measurement on titanium nucleus provides essential information to understand the neutrino scattering on argon, large contribution to which comes from scattering off neutrons. Here we report the first experimental study of electron-titanium scattering as double-differential cross section at beam energy E = 2.222 GeV and electron-scattering angle θ = 15.541°, measured over a broad range of energy transfer, spanning the kinematical regions in which quasielastic scattering and delta production are the dominant reaction mechanisms. In conclusion, the data provide valuable new information needed to develop accurate theoretical models of the electromagnetic and weak cross sections of these complex nuclei in the kinematic regime of interest to neutrino experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Possibility of Studying Neutron–Neutron Correlations in Halo Nuclei

An experimental investigation of the reaction of core pickup from {sup 6}He and {sup 11}Li two-neutronhalo nuclei is proposed. In such experiments, neutron–neutron correlations in a halo nucleus will be assessed on the basis of the energy of a neutron–neutron quasibound state. A detailed kinematical simulation of the reaction {sup 6}He + {sup 2}H → {sup 6}Li + (nn) →{sup 6} Li + n + n is performed. It is shown that the energy of the quasibound state in question can determined from the shape of the energy spectrum of neutrons originating from the breakup of this state. In the proposed exclusive experiment, a beam of {sup 6}He ({sup 11}Li) nuclei with an energy of about 5 to 10 MeV per nucleon interacts with a deuterated-polyethylene target. This will permit detecting charged particles ({sup 6}Li and {sup 11}Be) and a neutron. On the basis of determining the energy of the neutron–neutron quasibound state, it will become possible to estimate the effective attraction between the valence neutrons in the field of the third particle (core).

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Report on the Second MPEX User Research Forum

The Material Plasma Exposure eXperiment (MPEX) User Research Forum (MURF), a 2 day workshop, was held virtually on September 13–14, 2021, to seek community input for MPEX, a new high-power linear plasma device that is currently being built at Oak Ridge National Laboratory (ORNL). This was the second MURF workshop. The first MURF workshop was held in October 2019 in La Jolla, California, and focused exclusively on the definition of the surface analysis station for MPEX. MPEX is designed to address crucial R&D gaps in plasma material interactions (PMI) for future fusion reactors. The MPEX plasma source and heating systems will allow plasma exposures of plasma-facing materials and components to prototype fusion reactor divertor plasma conditions. The MPEX design accommodates the introduction of previously neutron-irradiated materials for fusion reactor-relevant plasma exposures. This capability will be unique worldwide. The US fusion program has advocated for such a device in numerous community reports in recent years, and now ORNL is building this new device. MPEX is a Major Item of Equipment project executed by the US Department of Energy’s Office of Science Fusion Energy Sciences.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Binding of SRSF4 to a novel enhancer modulates splicing of exon 6 of Fas pre-mRNA

Highlights: • SRSF4 expression promotes exon 6 inclusion of Fas pre-mRNA. • A stronger 5′ splice-site of exon 6 is required for SRSF4-mediated regulation on exon 6 splicing. • SRSF4 functionally targets GGGGUG RNA sequence on exon 6. • SRSF4 directly interacts with GGGGUG sequence on exon 6. Alternative splicing of exon 6 in Fas pre-mRNA generates a membrane bound pro-apoptotic isoform or soluble anti-apoptotic isoform. SRSF4 is a member of Arginine-Serine rich (SR) protein family. Here we demonstrate that increased SRSF4 expression stimulates exon 6 inclusion, and that reduced SRSF4 expression promotes exon 6 exclusion. We also show that weaker but not stronger 5’ splice-site strength of exon 6 abolishes the SRSF4 effects on exon 6 splicing. Furthermore, we identified a novel enhancer on exon 6, on which SRSF4 interacts functionally and physically. Our results illustrate a novel regulatory mechanism of Fas pre-mRNA splicing.

60 APPLIED LIFE SCIENCES↗