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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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DOE OSTI2024

Lifetimes of excited states in $^{16}$C as a benchmark for ab initio developments

Lifetimes of higher-lying states ($2_2^+$ and $4_1^+$) in 16 C have been measured, employing the Gammasphere and Microball detector arrays, as key observables to test and refine ab initio calculations based on interactions developed within chiral Effective Field Theory. The presented experimental constraints to these lifetimes of $\tau ({2_2^+}) = [244, 446]\,~\textrm{fs}$ and $\tau ({4_1^+}) = [1.8, 4]\,~\textrm{ps}$, combined with previous results on the lifetime of the $2_1^+$ state of 16 C, provide a rather complete set of key observables to benchmark the theoretical developments. We present No-Core Shell-Model calculations using state-of-the-art chiral 2- (NN) and 3-nucleon (3N) interactions at next-to-next-to-next-to-leading order for both the NN and the 3N contributions and a generalized natural-orbital basis (instead of the conventional harmonic-oscillator single-particle basis) which reproduce, for the first time, the experimental findings remarkably well. The level of agreement of the new calculations as compared to the CD-Bonn meson-exchange NN interaction is notable and presents a critical benchmark for theory.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

Ninth International Workshop on Chiral Dynamics, 2018

The Ninth International Workshop on Chiral Dynamics (CD18) was hosted by the Triangle Universities Nuclear Laboratory (TUNL) and held on the campus of Duke University in Durham, NC. The workshop was from September 17 th to 21 st , 2018. This series of workshops, which started at MIT in 1994, brings together theorists and experimentalists every three years to discuss the status and challenges in the physics of low-energy quantum chromodynamics (QCD), Goldstone Boson dynamics, meson-baryon interactions, few-body physics, lattice QCD and Chiral Perturbation Theory. The last workshop was jointly hosted by the Department of Physics of the University of Pisa and the Pisa branch of the Istituto Nazionale di Fisica Nucleare in July 2015. Previous hosts of the workshop include MIT in 1994, the University of Mainz in 1997, Jefferson Lab in 2000 and 2012, the University of Bonn in 2003, TUNL and Duke University in 2006, and the University of Bern in 2009. Hosting this workshop is an important and substantial service to the international low-energy QCD physics community. Nearly 120 participants attended the workshop, which delivered twenty plenary talks, and over ninety parallel presentations. Proceedings of the workshop are published in Proceedings of Science at https://pos.sissa.it/317/. These proceedings present topics convened in this 9 th workshop and provide a comprehensive review of the field, highlighting recent accomplishments and discussing challenges that will motivate research in the coming years.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2026

Quasielastic $\overrightarrow{^{3}He}$ $(\overrightarrow{e},e′)$ asymmetry in the threshold region with a longitudinally polarized target

We report on the measurements of the double-spin asymmetry from electron- 3 He scattering in the threshold region of two- and three-body breakup of 3 He for 4-momentum transfer values of 0.1 and 0.2 (GeV/c) 2 . The measurement was done at Jefferson Lab using a polarized 3 He target with its spin aligned parallel to the beam direction. This asymmetry is sensitive to a combination of spin-dependent response functions not previously measured and may highlight differences in two body forces, meson-exchange currents and final-state interactions. The results of this measurement serve as a test of our understanding of few-body systems. When compared with calculations from plane wave impulse approximation and Faddeev calculations, we found that the latter, which use modern nuclear potentials and prescriptions for meson-exchange currents, demonstrate an overall good agreement with data.

Few-body nuclei↗

DOE OSTI2025

Neutrino-Nucleus Scattering Cross Sections at Medium Energies

The weak interactions of neutrinos with other Standard Model particles are well described within the Standard Model of particle physics. However, modern accelerator-based neutrino experiments employ nuclei as targets, where neutrinos interact with bound nucleons, turning a seemingly simple electroweak process into a complex many-body problem in nuclear physics. At the time of writing this Encyclopedia of Particle Physics chapter, neutrino-nucleus interactions remain one of the leading sources of systematic uncertainty in accelerator-based neutrino oscillation measurements. This chapter provides a pedagogical overview of neutrino interactions with nuclei in the medium-energy regime, spanning a few hundred MeV to several GeV. It introduces the fundamental electroweak formalism, outlines the dominant interaction mechanisms - including quasielastic scattering, resonance production, and deep inelastic scattering - and discusses how nuclear effects such as Fermi motion, nucleon-nucleon correlations, meson-exchange currents, and final-state interactions modify observable cross sections. The chapter also presents a brief survey of the foundational and most widely used theoretical models for neutrino-nucleus cross sections, together with an overview of current and upcoming accelerator-based neutrino oscillation experiments that are shaping the field. Rather than targeting experts, this chapter serves as a primer for advanced undergraduates, graduate students, and early-career researchers entering the field. It provides a concise foundation for understanding neutrino-nucleus scattering, its relevance to oscillation experiments, and its broader connections to both particle and nuclear physics.

Pandey, Vishvas [Fermilab] (ORCID:0000000230827987↗

DOE OSTI2021

Dynamical model of φ meson photoproduction on the nucleon and 4 He

We investigate φ meson photoproduction on the nucleon and the 4 He targets within a dynamical model approach based on a Hamiltonian which describes the production mechanisms by the Pomeron-exchange, meson-exchanges, φ radiations, and nucleon resonance excitations mechanisms. The final φN interactions are included being described by the gluon-exchange, direct φN couplings, and the box-diagrams arising from the couplings with πN, ρN, KΛ, and KΣ channels. The parameters of the Hamiltonian are determined by the experimental data of γp → φp from the CLAS Collaboration. The resulting Hamiltonian is then used to predict the coherent φ-meson production on the 4 He targets by using the distorted-wave impulse approximation. For the proton target, the final φN rescattering effects, as required by the unitarity condition, are found to be very weak, which supports the earlier calculations in the literature. For the 4 He targets, the predicted differential cross sections are in good agreement with the data obtained by the LEPS Collaboration. Furthermore, the role of each mechanism in this reaction is discussed and predictions for a wide range of scattering angles are presented, which can be tested in future experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2026

Improving neutrino oscillation measurements through event classification

Precise neutrino energy reconstruction is essential for next-generation long-baseline oscillation experiments, yet current methods remain limited by large uncertainties in neutrino-nucleus interaction modeling. Even so, it is well established that different interaction channels produce systematically varying amounts of missing energy and therefore yield different reconstruction performance–information that standard calorimetric approaches do not exploit. We introduce a strategy that incorporates this structure by classifying events according to their underlying interaction type prior to energy reconstruction. Using supervised machine-learning techniques trained on labeled generator events, we leverage intrinsic kinematic differences among quasielastic scattering, meson-exchange current, resonance production, and deep-inelastic scattering processes. A cross-generator testing framework demonstrates that this classification approach is robust to microphysics mismodeling and, when applied to a simulated DUNE 𝜈 𝜇 disappearance analysis, yields improved accuracy and sensitivity at the 10%–20% level. These results highlight a practical path toward reducing reconstruction-driven systematics in future oscillation measurements.

Ellis, Sebastian A. R. [King's College, London (Un↗

DOE OSTI2021

First measurement of the asymmetry and the Gerasimov-Drell-Hearn integrand from the 3 $\vec{H}$e ($\vec{γ},p$) 2 H reaction at an incident photon energy of 29 MeV

The first measurement of the 3 $\vec{H}$e ($\vec{γ},p$) 2 H process was performed at the High Intensity γ-ray Source ( HIγS ) facility at Triangle Universities Nuclear Laboratory using a circularly polarized, monoenergetic γ -ray beam and a longitudinally polarized 3 He target. The spin-dependent asymmetry and the contribution from the two-body photodisintegration to the 3 He Gerasimov-Drell-Hearn integrand are extracted and compared with state-of-the-art three-nucleon system calculations at the incident photon energy of 29 MeV. The data are in general agreement with the various theoretical predictions based on the Siegert theorem or on explicit inclusion of meson-exchange currents.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗