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DOE OSTI2024

Simultaneous extraction of the weak radius and the weak mixing angle from parity-violating electron scattering on 12 C

We study the impact of nuclear structure uncertainties on a measurement of the weak charge of 12 C at the future Mainz Energy Recovering Superconducting Accelerator (MESA) facility in Mainz. Information from a large variety of nuclear models, accurately calibrated to the ground-state properties of selected nuclei, suggest that a 0.3% precision measurement of the parity-violating asymmetry at forward angles will not be compromised by nuclear structure effects, thereby allowing a world-leading determination of the weak charge of 12 C . Furthermore, we show that a combination of measurements of the parity-violating asymmetry at forward and backward angles for the same electron-beam energy can be used to extract information on the nuclear weak charge distribution. We conclude that a 0.34% precision on the weak radius of 12 C may be achieved by performing a 3% precision measurement of the parity-violating asymmetry at backward angles.

Electroweak interaction↗

NASA NTRS1987

Fe K features as probes of the nuclear reflection region in Seyfert galaxies

The warm electron scattering region posited in 1985 by Antonucci and Miller to exist in NGC 1068 may be a characteristic feature of Seyfert galaxies. Whenever it exists, it presents a unique signature in Fe X-ray features. Predictions of the strength of the Fe K-edge and K-alpha line in both type 1 and type 2 Seyfert galaxies are presented and interpreted.

Krolik, Julian H.↗

DOE OSTI2025

The nuclear charge radius of 13 C

The size is a key property of a nucleus. Accurate nuclear radii are extracted from elastic electron scattering, laser spectroscopy, and muonic atom spectroscopy. The results are not always compatible, as the proton-radius puzzle has shown most dramatically. Beyond helium, precision data from muonic and electronic sources are scarce in the light-mass region. The stable isotopes of carbon are an exception. We present a laser spectroscopic measurement of the root-mean-square (rms) charge radius of 13 C and compare this with ab initio nuclear structure calculations. Measuring all hyperfine components of the 2 3 S → 2 3 P fine-structure triplet in 13 C 4+ ions referenced to a frequency comb allows us to determine its center-of-gravity with accuracy better than 2 MHz although second-order hyperfine-structure effects shift individual lines by several GHz. We improved the uncertainty of R c ( 13 C) determined with electrons by a factor of 6 and found a 3σ discrepancy with the muonic atom result of similar accuracy.

Müller, Patrick [Technical Univ. of Darmstadt (Ger↗

DOE OSTI2025

Background subtraction in inelastic scattering measurements using machine learning

Identifying, isolating, and subtracting background from the signal of interest is vital for nuclear physics experiments. These backgrounds introduce unwanted uncertainties that must be accounted for properly to extract accurate results from the signals. In nuclear reaction measurements, the typical contaminants are carbon and oxygen, contributing to background signals, and complicating the measurement of the light ejectiles. For instance, in the inelastic scattering measurement of a 20.9-MeV proton beam on 96 Mo, the 96 Mo target was contaminated with carbon and oxygen. Here, we used random forest, a machine learning algorithm commonly used for classification and regression tasks, to separate the inelastic scattering on the carbon and oxygen contaminants from the data of interest resulting from 96 Mo(p, p').

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2025

Measurement of cross sections for mesonless charged-current muon neutrino interactions on argon with and without protons at MicroBooNE

urrent and upcoming neutrino experiments at Fermilab will rely on liquid argon time projection chambers (LArTPCs) as the primary detector technology. To reach the ambitious precision required for their physics goals, a detailed understanding of neutrino-argon scattering must be achieved. For the present Short-Baseline Neutrino program, the dominant reaction channel is charged-current muon neutrino interactions leading to mesonless final states with and without protons. Using a large data set of neutrino interactions recorded by the MicroBooNE LArTPC detector at Fermilab, we report progress towards new measurements of differential cross sections in this channel. The analysis leverages multiple event reconstruction paradigms and observables specifically chosen to maximize sensitivity to nuclear effects of interest for improving neutrino scattering models. Related previous cross-section results from MicroBooNE and a preview of what to expect from the new analysis will both be featured in this presentation.

Liu, Liang [Fermilab]↗

DOE OSTI2025

Quasielastic lepton-nucleus scattering and the correlated Fermi gas model

The neutrino research program in the coming decades will require improved precision. A major source of uncertainty is the interaction of neutrinos with nuclei that serve as targets for such experiments. Broadly speaking, this interaction often depends, e.g., for charge-current quasielastic scattering, on the combination of “nucleon physics,” expressed by form factors, and “nuclear physics,” expressed by a nuclear model. It is important to get a good handle on both. We present a fully analytic implementation of the correlated Fermi gas model for electron-nucleus and charge-current quasielastic neutrino-nucleus scattering. The implementation is used to compare separately form factors and nuclear model effects for both electron-carbon and neutrino-carbon scattering data. Published by the American Physical Society 2025

Bhattacharya, Bhubanjyoti (ORCID:000000032238321X)↗

NASA NTRS1994

Multiple-scattering model for inclusive proton production in heavy ion collisions

A formalism is developed for evaluating the momentum distribution for proton production in nuclear abrasion during heavy ion collisions using the Glauber multiple-scattering series. Several models for the one-body density matrix of nuclei are considered for performing numerical calculations. Calculations for the momentum distribution of protons in abrasion are compared with experimental data for inclusive proton production.

Cucinotta, Francis A.↗

DOE OSTI2024

Ab initio leading order effective potential for elastic proton scattering based on the symmetry-adapted no-core shell model

Calculating microscopic optical potentials for elastic scattering at intermediate energies from light nuclei in an ab initio fashion within the Watson expansion has been established within the last few years. Based on the Watson expansion of the multiple scattering series, we employ a nonlocal translationally invariant nuclear density derived within the symmetry-adapted no-core shell model (SA-NCSM) framework from a chiral next-to-next-to-leading order (NNLO) nucleon-nucleon interaction and the very same interaction for a consistent full-folding calculation of the effective (optical) potential for nucleon-nucleus scattering for medium-heavy nuclei. The leading order effective (optical) folding potential is computed by integrating over a translationally invariant SA-NCSM one-body scalar density, spin-projected momentum distribution, and the Wolfenstein amplitudes 𝐴, 𝐶, and 𝑀. The resulting nonlocal potentials serve as input for a momentum space Lippmann-Schwinger equation. In the SA-NCSM, the model space is systematically up-selected using Sp⁡(3,ℝ) symmetry considerations. For the light nucleus of 6 He, we establish a systematic selection scheme in the SA-NCSM for scattering observables. Then, we apply this scheme to calculations of scattering observables, such as differential cross sections, analyzing powers, and spin rotation functions for elastic proton scattering from 20 Ne and 40 Ca in the energy regime between 65 and 200 MeV, and compare to available data. Furthermore, our calculations show that the leading order effective nucleon-nucleus potential in the Watson expansion of multiple scattering theory obtained from an up-selected SA-NCSM model space describes 40 Ca elastic scattering observables reasonably well to about 60 degrees in the center-of-mass frame, which coincides roughly with the validity of the NNLO chiral interaction used to calculate both the nucleon-nucleon amplitudes and the one-body scalar and spin nuclear densities.

Ab initio calculations↗

DOE OSTI2026

Transverse Kinematic Imbalance in MicroBooNE's New nue CC0pi Measurements

Neutrino-nucleus cross section measurements require accurate modelling of neutrino interactions. Neutrino beams are not monoenergetic, and the energy of each interaction must instead be modelled using nuclear interaction assumptions. This introduces significant systematic uncertainty into cross section measurements. Effects such as Fermi motion, nuclear correlations, and final-state interactions (FSI) smear the underlying quasi-elastic scattering signal, making it difficult to disentangle genuine quasi-elastic kinematics from nuclear effects across the full range of interaction channels (QE, MEC, RES, DIS) probed in these measurements. Transverse Kinematic Imbalance (TKI) variables, such as $\delta p_T$ and $\delta \alpha_T$, probe this same phase space by exploiting the fact that the incoming neutrino has zero transverse momentum ($\vec{p}_T^{\,\nu} = 0$). Any measured transverse imbalance in the final state therefore arises from nuclear effects rather than from uncertainty in the incident neutrino energy, allowing cross section measurements to select a phase space that is rich in quasi-elastic-like events with minimal contamination from FSI and other nuclear effects, independent of energy reconstruction. Recent unfolded MicroBooNE cross section measurements of electron-neutrino charged-current interactions with zero pions and at least one proton ($\nu_e$ CC0$\pi$, 1eNp0$\pi$) show that several leading nuclear interaction generators (including GENIE variants, NuWro, GiBUU, and NEUT) reproduce the differential cross section in electron energy reasonably well, but consistently struggle to describe the differential cross section in the cosine of the leading proton's angle, yielding lower $p$-values across all seven generators tested. This tension points to a more fundamental, kinematics-driven disagreement between data and generators that is not visible in energy-only cross section observables. This is precisely the regime TKI variables are designed to probe. Following previous TKI cross section measurements with muon-neutrino data in MicroBooNE, this poster presents the case for extending the TKI framework to electron-neutrino cross section measurements as a next step to isolate and characterize the source of the observed generator tension in proton kinematics.

Burridge, Jessica [U. Manchester (main)] (ORCID:00↗

DOE OSTI2025

Neutron Scattering Cross Sections: (n,n′), (n,n′γ), and (n,γ) Measurements (Final Technical Report)

This technical report discusses the outcomes from a grant to the University of Dallas in collaboration with the University of Kentucky, the United States Naval Academy and Mississippi State University to measure neutron cross sections and to provide educational opportunities in nuclear science for undergraduate and graduate students and postdoctoral scholars.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

NASA NTRS1996

Light ion components of the galactic cosmic rays: Nuclear interactions and transport theory

Light nuclei are present in the primary galactic cosmic rays (GCR) and are produced in thick targets due to projectile or target fragmentation from both nucleon and heavy induced reactions. In the primary GCR, He-4 is the most abundant nucleus after H-1. However, there are also a substantial fluxes of H-2 and He-3. In this paper we describe theoretical models based on quantum multiple scattering theory for the description of light ion nuclear interactions. The energy dependence of the light ion fragmentation cross section is considered with comparisons of inclusive yields and secondary momentum distributions to experiments described. We also analyze the importance of a fast component of lights ions from proton and neutron induced target fragementation. These theoretical models have been incorporated into the cosmic ray transport code HZETRN and will be used to analyze the role of shielding materials in modulating the production and the energy spectrum of light ions.

Cucinotta, F. A.↗

DOE OSTI2024

Understanding interfacial crystallization dynamics on carbon fiber reinforced polypropylene composite manufacturing

Reinforcing polymers with discontinuous fibers improves mechanical properties, such as strength and stiffness, and in some cases achieve isotropic properties, rendering them suitable for various engineering applications. Matrix materials are generally highly engineered thermosets (e.g. crosslinked epoxies), bonded to the fiber periphery by proprietary surface and sizing chemistries. Semicrystalline thermoplastic matrices are less utilized due to poor fiber-matrix bonding resulting in inefficient interfacial load-transfer in reinforced composites. However, flexibility with melt-processing or molding conditions can be leveraged to promote non-covalent interfacial bonding between matrix and fiber via crystallization of the matrix onto fiber surface. In the present study, we utilize a co-mingle chopped carbon and isotactic polypropylene fibers to form isotropic composites, tailoring interfacial immobilized matrix or interphase morphology to optimize performance through precise control of thermal processing/molding windows. Calorimetry and optical microscopy were employed to investigate the impact of carbon fiber at various volume fractions (10, 20, and 30 %) on isotactic polypropylene crystallization and mechanical performance. Variations in mechanical properties correspond to the structural evolution of the interfacial region and are correlated to underlying microstructural attributes using wide-angle X-ray scattering, thermal analysis, and low-field nuclear magnetic resonance spectroscopy. These results provide a practical framework for the manufacturing of thermoplastic matrix composites. In conclusion, the results presented provide a guide for the strategic optimization of interphase design, showcasing tailorable tensile strengths which outperform any isotactic polypropylene carbon fiber composites previously reported in literature.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Accelerating multiscale electronic stopping power predictions with time-dependent density functional theory and machine learning

Knowing the rate at which particle radiation releases energy in a material, the “stopping power,” is key to designing nuclear reactors, medical treatments, semiconductor and quantum materials, and many other technologies. While the nuclear contribution to stopping power, i.e., elastic scattering between atoms, is well understood in the literature, the route for gathering data on the electronic contribution has for decades remained costly and reliant on many simplifying assumptions, including that materials are isotropic. We establish a method that combines time-dependent density functional theory (TDDFT) and machine learning to reduce the time to assess new materials to hours on a supercomputer and provide valuable data on how atomic details influence electronic stopping. Our approach uses TDDFT to compute the electronic stopping from first principles in several directions and then machine learning to interpolate to other directions at a cost of 10 million times fewer core-hours. We demonstrate the combined approach in a study of proton irradiation in aluminum and employ it to predict how the depth of maximum energy deposition, the “Bragg Peak,” varies depending on the incident angle—a quantity otherwise inaccessible to modelers and far outside the scales of quantum mechanical simulations. The lack of any experimental information requirement makes our method applicable to most materials, and its speed makes it a prime candidate for enabling quantum-to-continuum models of radiation damage. The prospect of reusing valuable TDDFT data for training the model makes our approach appealing for applications in the age of materials data science.

36 MATERIALS SCIENCE↗

DOE OSTI2026

LArCADe | Liquid Argon Charge Amplification Devices

The Liquid Argon Charge Amplification Devices (LArCADe) project is an R$\&$D effort aimed at developing instrumentation capable of lowering detection thresholds for ionization signatures in liquid and gaseous argon detectors and achieving O(100 $\mu$m) position resolution. The core concept is the use of sharp “tip arrays” that generate strong local electric-field enhancement, enabling charge amplification and collection with improved spatial resolution. A key physics motivation for this work is to enhance the experimental sensitivity of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) measurements to low-energy nuclear recoils by enabling spatially resolved charge reconstruction at reduced ionization thresholds, with the goal of achieving event-by-event energy reconstruction for interactions originating from localized accelerator or astrophysical neutrino sources. This poster will present the current status of the instrumentation R$\&$D, which leverages Fermilab’s Noble Liquid Test Facility and UC Santa Barbara’s Nanofabrication Facility, and will discuss the potential physics impact of this technology.

Antonakis, Alexander [UC, Santa Barbara]↗

NASA NTRS1973

Prospects for Nuclear-gamma-ray Astronomy

An analysis was made of prospects for gamma rays coming from two sources outside the solar system: (1) radioactive decay of fresh nuclear products to explosive nucleosynthesis, and (2) scattering of low energy cosmic rays. The former should be detectable and will provide a factual base for many suppositions about the site and history of nucleosynthesis. The latter may be detectable and, if so, will probably provide factual information about high-flux regions of cosmic radiation.

Clayton, D. D.↗

NASA NTRS1991

NGC 1068 - Resolution of nuclear structure in the optical continuum

The HST Planetary Camera has been used to obtain an optical continuum image of the Seyfert galaxy NGC 1068. The image reveals a bright nucleus embedded in an irregular cloudlike structure which is well-differentiated against the background of the galaxy. The nucleus is resolved, with an FWHM of about 0.15 arcsec, or 11 pc. There is no evidence for any unresolved nuclear component. The precise geometry of the scattering region cannot yet be inferred. The cloud surrounding the nucleus is elongated in the NE-SSW direction and has extreme dimensions of 3.5 arcsec x 1.7 arcsec. The brightness centroid is situated 0.4 arcsec SW of the nucleus. It is concluded that the light from the cloud is contributed largely by stars, but that the appearance of the cloud is distinctly dissimilar to what is expected from young or old stellar systems and bears to simple relationship to the numerous features that have heretofore been resolved at other wavelengths.

Lynds, Roger↗

NASA NTRS1990

Single nucleon emission in relativistic nucleus-nucleus reactions

Significant discrepancies between theory and experiment have previously been noted for nucleon emission via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work investigates the hypothesis that these discrepancies have arisen due to uncertainties about how to deduce the experimental electromagnetic cross section from the total measured cross section. An optical-model calculation of single neutron removal is added to electromagnetic cross sections and compared to the total experimental cross sections. Good agreement is found thereby resolving some of the earlier noted discrepancies. A detailed comparison to the recent work of Benesh, Cook, and Vary is made for both the impact parameter and the nuclear cross section. Good agreement is obtained giving an independent confirmation of the parametrized formulas developed by those authors.

NASA Discipline Radiation Health↗

DOE OSTI2025

Weak-charge radius of 40 Ar: From CREX constraints to CE⁢𝜈⁢NS sensitivity

Despite significant theoretical efforts, the CREX-PREX dilemma remains unresolved, preventing the reliable prediction of neutron (or weak-charge) radii that, besides their intrinsic nuclear-structure interest, often serve to quantify the impact of nuclear uncertainties in searches for new physics. Coherent elastic neutrino-nucleus scattering is a clean and attractive portal to new physics, whose sensitivity may be impacted by such nuclear uncertainties. In this paper I use CREX as the basis, together with a strong calcium-argon correlation, to provide a robust baseline for the weak radius of 40 Ar : 𝑅$^{40}_{wk}$ = 3.452 ± 0.028 (stat) ± 0.022 (syst) fm. Here, the weak radius of argon is an observable, highly relevant to ongoing and future liquid-argon campaigns, that encodes the loss of coherence at small momentum transfers.

39 ≤ A ≤ 58↗