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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

The DUNE Experiment

The Deep Underground Neutrino Experiment (DUNE) is a next generation long-baseline neutrino experiment built to answer some of the most fundamental questions in the universe. DUNE will consist of two neutrino detectors placed in the world’s most intense neutrino beam facility named as Long-Baseline Neutrino Facility (LBNF). It consists of a near detector and a far detector that is comprised initially of two modules and eventually of four modules, each of fiducial mass 17.5 ktons of liquid Argon. The far detector is located 1300 km from the beam source placed underground at the Sanford Underground Research Laboratory in Lead, South Dakota. DUNE will measure the un-oscillated neutrinos nucleus interactions at near detector and oscillated interactions at far detector which will be able to address the questions about the preponderance of matter over antimatter in the early universe, searches for leptonic charge-parity symmetry violation, proton decay, supernova neutrino bursts and unification of forces. This article discussed the goals and physics of the DUNE experiment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Generalized Ginsparg-Wilson relations

We give a general derivation of Ginsparg-Wilson relations for both Dirac and Majorana fermions in any dimension. These relations encode continuous and discrete chiral, parity and time-reversal anomalies and will apply to the various classes of free-fermion topological insulators and superconductors (in the framework of a relativistic quantum field theory in Euclidean spacetime). We show how to formulate the exact symmetries of the lattice action and the relevant index theorems for the anomalies. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Partial-wave projection of the one-particle exchange in three-body scattering amplitudes

As the study of three-hadron physics from lattice QCD matures, it is necessary to develop proper analysis tools in order to reliably study a variety of phenomena, including resonance spectroscopy and nuclear structure. Reconstructing the three-particle scattering amplitude requires solving integral equations, which can be written in terms of data-constrained dynamical functions and physical on shell quantities. The driving term in these equations is the so-called one-particle exchange, which leads to a kinematic divergence for particles on mass shell. A vital component in defining three-particle amplitudes with definite parity and total angular momentum, which are used in spectroscopic studies, is to project the one-particle exchange into definite partial waves. We present a general procedure to construct exact analytic partial-wave projections of the one-particle exchange contribution for any system composed of three spinless hadrons. Our result allows one full control over the analytic structure of the projection, which we explore for some low-lying partial waves with applications to three pions. Published by the American Physical Society 2024

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1972

The calculation of neutron capture gamma-ray yields for space shielding applications

The application of nuclear models to the calculation of neutron capture and inelastic scattering gamma yields is discussed. The gamma ray cascade model describes the cascade process in terms of parameters which either: (1) embody statistical assumptions regarding electric and magnetic multipole transition strengths, level densities, and spin and parity distributions or (2) are fixed by experiment such as measured energies, spin and parity values, and transition probabilities for low lying states.

Yost, K. J.↗
DOE OSTI2023

An Overview of Global Gender Initiatives for Women in the Nuclear and Radiological Fields

Currently, women make up less than a quarter of nuclear and radiological industry professionals; women are consistently underrepresented in leadership positions in the sector and are a minority in WMD1 and STEM classes. Recognizing this problem in our industry, a growing number of region-specific groups (the Black Sea Women in Nuclear Network2 and WiN Global subgroup Women in Nuclear Southeast Asia3 ), government created initiatives, and various fellowship and grant programs (the IAEA’s Marie Sklodowska-Curie Fellowship Programme4 and CFRD Global’s grant program5 ) work to increase female participation and success in this historically male-dominated profession. While these valuable initiatives exist, there is no single, consolidated collection of resources for women in nuclear and radiological fields. This paper will attempt to fill that gap. It will: provide an overview of gender-based initiatives and opportunities, investigate these organizations’ mission and purpose, highlight the lack of gender statistics at all working levels as a barrier for measuring gender parity improvement (site, state, country and international), and propose that these organizations leverage their networks and expertise to enhance gendered data collection in the field.

Arapoff, Julia↗
NASA NTRS1994

Theoretical Studies of PNC in Molecules: current Capabilites, Future Prospects, and Issues

The current capabilities of relativistic electronic structure codes for calculations on molecules such as TlF and YbF, which are of interest in the study of parity non-conservation, will be presented. The issues of basis set size and correlation methods will be discussed, and planned developments of the codes which would extend the range of their capabilities will be outlined. Issues of the sensitivity of the desired properties to the form of the nuclear potential and the flexibility of the wave function near the nucleus will be raised to stimulate discussion.

Dyall, Kenneth G.↗
DOE OSTI2021

Nuclear Data Sheets for A=194

Experimental nuclear structure and decay data are evaluated for all of 14 known nuclides of mass 194 (Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, At, Rn). Detailed evaluated spectroscopic information is presented for each reaction and decay experiment, and by combining all the available data, recommended values are provided for energies, spins and parities and half-lives of levels, together with energies, branching ratios and multipolarities of gamma radiations from the levels, and characteristics of beta and alpha radiations in radioactive decays. No excited states have yet been identified in 194 Ta, 194 W, and 194 Rn. Only limited spectroscopic data are available for 194 Re, with a 45–μs isomer identified, but its absolute energy yet to be determined. Only two levels at unknown absolute energies are reported for 194 At, both of which are isomeric but neither can be unambiguously identified as the ground state. Data are scarce for 194 Os, 194 Bi and 194 Po, while 194 Pt, 194 Au, 194 Hg, 194 Tl and 194 Pb are well studied through decays and reactions. For 194 Ir, although a major (n, γ), E=thermal study and two particle-transfer studies provide large amounts of spectral data, still several problematic issues are found in the assignment of multipolarities for the secondary gamma transitions in the (n, γ) study by 2008Ba25, 1998Ba85 and 1998Ba42, all from the same group. Some issues have been resolved by the evaluators, but we suggest that further experimental work is needed on 194 Ir structure to resolve standing issues, and verify the conclusions made by 2008Ba25. Furthermore, our attempt to contact the prime authors of the 2008Ba25 paper was not successful. The present work supersedes all the earlier evaluations of A=194 nuclides by 2006Si17, 1996Br26, 1989Si01 and 1972Au11.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Physics-based hybrid machine learning for critical heat flux prediction with uncertainty quantification

Critical heat flux (CHF) is a key quantity in nuclear system modeling due to its impact on heat transfer, safety margins, and reactor performance. This study develops and validates an uncertainty-aware hybrid modeling approach that combines machine learning with physics-based models to predict CHF in cases of dryout. The Biasi and Bowring empirical correlations were paired with three ML uncertainty quantification (UQ) techniques: deep neural network (DNN) ensembles, Bayesian neural networks (BNNs), and deep Gaussian processes (DGPs). A pure ML model without a base model was evaluated for comparison. Model performance was assessed under plentiful (7,350 points) and limited (9 points) training data scenarios using parity, uncertainty distributions, and calibration curves. Results show that the Biasi hybrid DNN ensemble achieved the best overall performance, with a mean absolute relative error of 1.846%, and well-calibrated uncertainty estimates. The BNN-based hybrids showed slightly higher error (2.14%) but superior uncertainty calibration. DGP models underperformed, with over 6% error and poor uncertainty calibration. All hybrid models outperformed pure machine learning configurations, demonstrating resistance against data scarcity. These findings indicate that hybrid modeling significantly improves predictive accuracy, interpretability, and resilience to data scarcity. The integration of uncertainty awareness provides actionable confidence in CHF predictions, which is vital for safety-critical decisions in nuclear applications. This hybrid approach offers a viable pathway for deploying ML models in reactor analysis tools while preserving domain knowledge and physical consistency.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2026

Deployment of Traditional and Hybrid Machine Learning for Critical Heat Flux Prediction in the CTF Thermal-Hydraulics Code

Critical heat flux (CHF) marks the transition from nucleate to film boiling, where heat transfer to the working fluid can rapidly deteriorate. Accurate CHF prediction is essential for efficiency, safety, and preventing equipment damage, particularly in nuclear reactors. Although widely used, empirical correlations frequently exhibit discrepancies when compared to experimental data, limiting their reliability in diverse operational conditions. Traditional machine learning (ML) approaches have demonstrated potential for CHF prediction but often suffer from limited interpretability, data scarcity, and insufficient knowledge of physical principles. Hybrid model approaches, which combine data-driven ML with base models, mitigate these concerns by incorporating prior knowledge of the domain. This study integrates an externally trained purely data-driven ML model and two hybrid models (using the Biasi and Bowring CHF correlations) within the CTF subchannel code via a custom Fortran framework. Performance was evaluated using two validation cases: a subset of the Nuclear Regulatory Commission (NRC) CHF database and the Bennett dryout experiments. In both cases, the hybrid models demonstrated significantly lower error metrics compared to conventional empirical correlations, with the best models often reducing relative error by about 5 percentage points. The pure ML model achieved comparable accuracy, outperforming the hybrid Biasi model in the NRC test case (3.3% versus 5.5% relative error) but exhibiting slightly higher error against the hybrid Bowring model in the Bennett test case (7.7% versus 6.1%). Trend analysis of error parity indicated that ML-based models reduced the tendency for CHF overprediction, improving overall accuracy. These results demonstrate that ML-based CHF models can be effectively integrated into subchannel codes and could potentially increase performance compared to conventional methods.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2020

Nuclear Data Sheets for A=233

The present evaluation of the known A=233 nuclides ( 233 Fr, 233 Ra, 233 Ac, 233 Th, 233 Pa, 233 U, 233 Np, 233 Pu, 233 Am, 233 Cm) and 233 Bk represents an update and revision, after 15 years of the previous evaluation of A=233 published by B. Singh and J.K. Tuli (2005Si15). Laboratory identification of 233 Bk nuclide is still considered as tentative. Various decay and reaction data are evaluated and compared. Adopted data, levels, gammas, level half-lives, spins, parities, and configuration assignments are provided. For 233 Fr, 233 Ra, 233 Ac, 233 Pu, 233 Am and 233 Cm, information is available for the respective ground states only. The decay schemes from β - decays of 233 Fr and 233 Ra, and from ε decay of 233 Am and 233 Cm are unknown, while those from β - decay of 233 Ac, and from ε decay of 233 Np are considered incomplete. The α decay of 237 Np to 233 Pa has been studied in detail by many investigators, yet the decay scheme is considered incomplete as several very low-energy transitions are involved, without the knowledge of their intensities, resulting in mismatch of directly measured α feedings and those deduced from γ-transition intensity balances. The decay schemes from α decays of 237 Am, 237 Cm and 237 Cf to respective A=233 daughters are considered incomplete. Particle-transfer and high-spin data are available for 233 Th, 233 Pa and 233 U nuclei, which remain the most extensively studied in this mass chain. However, data for half-lives for the excited states are available only for one level in 233 Pa, and for five levels in 233 U, thus limiting the knowledge of reduced transition probabilities in this mass chain.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Measuring the surface thickness of the weak charge density of nuclei

The present PREX-II and CREX experiments are measuring the rms radius of the weak charge density of Pb 208 and Ca 48 . We discuss the feasibility of a new parity violating electron scattering experiment to measure the surface thickness of the weak charge density of a heavy nucleus. Additionally, once PREX-II and CREX have constrained weak radii, an additional parity violating measurement at a momentum transfer near 0.76 fm - 1 for Pb 208 or 1.28 fm - 1 for Ca 48 can determine the surface thickness.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Neutron transfer reactions on the ground state and isomeric state of a 130 Sn beam

The structure of nuclei around the neutron-rich nucleus 132 Sn is of particular interest due to the vicinity of the Z = 50 and N = 82 shell closures and the r-process nucleosynthetic path. Four states in 131 Sn with a strong single-particle-like component have previously been studied via the (d,p) reaction, with limited excitation energy resolution. Here, the 130 Sn( 9 Be, 8 Be) 131 Sn and 130 Sn( 13 C, 12 C) 131 Sn single-neutron transfer reactions were performed in inverse kinematics at the Holifield Radioactive Ion Beam Facility using particle-γ coincidence spectroscopy. The uncertainties in the energies of the single-particle-like states have been reduced by more than an order of magnitude using the energies of γ rays. The previous tentative J π values have been confirmed. Decays from high-spin states in 131 Sn have been observed following transfer on the isomeric component of the 130 Sn beam. The improved energies and confirmed spin-parities of the p-wave states important to the r-process lead to direct-semidirect cross-sections for neutron capture on the ground state of 130 Sn at 30 keV that are in agreement with previous analyses. A similar assessment of the impact of neutron-transfer on the isomer would require significant nuclear structure and reaction theory input. There are few measurements of transfer reaction on isomers, and this is the first on an isomer in the 132 Sn region.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Information Content of the Parity-Violating Asymmetry in Pb 208

The parity-violating asymmetry A PV in 208 Pb, recently measured by the PREX-2 Collaboration, is studied using modern relativistic (covariant) and nonrelativistic energy density functionals. We first assess the theoretical uncertainty on A PV which is intrinsic to the adopted approach. To this end, we use quantified functionals that are able to accommodate our previous knowledge on nuclear observables such as binding energies, charge radii, and the dipole polarizability α D of 208 Pb. We then add the quantified value of A PV together with α D to our calibration dataset to optimize new functionals. Based on these results, we predict a neutron skin thickness in 208 Pb r skin = 0.19 ± 0.02 fm and the symmetry-energy slope L = 54 ± 8 MeV. These values are consistent with other estimates based on astrophysical data and are significantly lower than those recently reported using a particular set of relativistic energy density functionals. Here, we also make a prediction for the A PV value in 48 Ca that will be soon available from the CREX measurement.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Properties of giant dipole resonances within an extended pairing model with a focus on spectral statistics

In this paper, we report on a study of the spectral features associated with dipole resonances in medium mass nuclei (E ≤ 12 MeV), as revealed in the framework of the spd-interacting boson model. The effect of pairing correlations on the theory follows from solutions obtained through an application of the Bethe Ansatz Equation. In general, calculated spectra around the critical point of the vibrational to γ-soft transitions appears to approach that of a Gaussian Orthogonal Ensemble, while near the rotational and vibrational limits of the theory the spectra show more regular behavior. Specifically, the results reveal that the statistical features of the spectra are sensitive to the vector boson pairing strength, c p , in the transition region; that is, when c p is zero, or when the system approaches one of its dynamical symmetries limits the spectrum display regular features, while for stronger c p values, or when near to the critical phase transition region, the spectral feature show more chaotic behavior. Overall, our results indicate that the statistical features are governed by the interplay between dipole resonant energies, pairing correlations, and interactions between and among the single and vector bosons modes of the theory. As part of this work we also found out that chaoticity occurs when results were fit to a Berry-Robnik distribution. Throughout our analyses, we used experimentally known information about both positive and negative parity states. Our findings suggest that dipole resonances appear to be best-described by Poisson statistics for A ≈ 32-138 nuclei.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Effects of triaxiality and residual n p interaction in the proton emission from Ho 140

Here we present a detailed theoretical investigation of proton emission from 140 Ho within the nonadiabatic quasiparticle approach. The calculated proton emission half-life reproduces well the measured data. The importance of triaxiality and of the residual np interaction are studied. The ground state spin and parity of 139 Dy (daughter) and 140 Ho (parent) are ascertained unambiguously as 7/2 + and 3 – , respectively, by analyzing the rotational energies, half-lives, and branching ratios.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Analog-antianalog isospin mixing in 47 K 𝛽−decay

Here, we have measured the isospin mixing of the 𝐼 𝜋 =1/2 + , 𝐸 𝑥 = 2.599 MeV state in nearly doubly magic 47 Ca with the isobaric analog 1/2 + state of 47 K . Using the TRIUMF atom trap for 𝛽 decay, we have measured a nonzero asymmetry of the progeny 47 Ca with respect to the initial 47 K spin polarization, which together with the 𝛽 asymmetry implies a nonzero ratio of Fermi to Gamow-Teller matrix elements 𝑦 = 0.098 ± 0.037 for the 1/2 + → 1/2 + transition. Interpreting 𝑦 as mixing between this state and the isobaric analog state implies a Coulomb matrix element magnitude 101 ± 37 keV. This relatively large matrix element supports a model from the literature of analog-antianalog isospin mixing, which predicts large matrix elements in cases involving excess neutrons over protons occupying more than one major shell. The result supports pursuing a search for time-reversal odd, parity-even, isovector interactions using a correlation in 47 K 𝛽 decay.

beta decay↗
DOE OSTI2026

First identification of resonant states in the {sup 45}V(p, {gamma}){sup 46}Cr reaction and their influence on the production of {sup 44}Ti in Core Collapse Supernovae

The observation of active 44Ti in supernova remnants offers the potential to solve one of the most debated questions in modern astrophysics, the exact underlying explosion mechanism of core collapse supernovae (CCSNe). In particular, a comparison between the predicted synthesized yield of 44Ti and the ejected flux is expected to allow for a determination of the mass cut of the star. Unfortunately, such comparisons are currently severely hindered by large uncertainties in the nuclear reactions governing the production and destruction of 44Ti. On this note, the astrophysical 45Vðp; γÞ46Cr reaction is expected to play a decisive role. We present the first experimental information on resonant states in the 45Vðp; γÞ46Cr reaction. Excitation energies have been measured with high precision for ten previously unknown, low-spin, proton-unbound states in 46Cr, and spin-parity-assignment constraints have been made using observed γ-decay patterns and shell-model calculations. We find that an l ¼ 1 resonance at 714 keV dominates the 45Vðp; γÞ46Cr reaction for the entire temperature range of α-rich freezeout. Moreover, the nominal rate is found to be ∼25–50% of previous estimates for T > 1.2 GK, indicating an increase in 44Ti production in CCSNe of ∼20–35%.

Cousins, C↗
DOE OSTI2020

Weak charge and weak radius of 12 C

Here, we present a feasibility study of a simultaneous sub-percent extraction of the weak charge and the weak radius of the 12 C nucleus using parity-violating electron scattering, based on a largely model-independent assessment of the uncertainties. The corresponding measurement is considered to be carried out at the future MESA facility in Mainz with E beam = 155 MeV. We find that a combination of a 0.3% precise measurement of the parity-violating asymmetry at forward angles with a 10% measurement at backward angles will allow to determine the weak charge and the weak radius of 12 C with 0.4% and 0.5% precision, respectively. These values could be improved to 0.3% and 0.2% for a 3% backward measurement. This experimental program will have impact on precision low-energy tests in the electroweak sector and nuclear structure.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗