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DOE OSTI2022

Verification of the AGREE and Serpent for the steady state HTR-10 benchmark problems

This paper provides results from steady state HTR-10 benchmark calculations performed using AGREE and Serpent that are compared to experimental results as well as calculations performed by INET. The purpose of completing this benchmark is to validate AGREE and Serpent for the prediction of HTGR operation so that they may ultimately be used to support licensing and deployment efforts of advanced reactors. The benchmark consists of several problems ranging from control rod worth calculations to k{sub eff} calculations at various temperatures. Overall, AGREE and Serpent show good agreement with the reference solutions and are effectively able to predict HTGR operation for a variety of steady state cases. The largest difference from the reference was for the initial core single rod worth, which is possibly due to the larger core helium cavity causing inaccuracies in the diffusion calculation whereas the control rod worth determined by Serpent and AGREE is much closer to the reference result for the full core loading. Moreover, in every benchmark problem, increasing the number of energy groups in the cross sections results in improved agreement of the AGREE result with the reference, although it also causes an increase in computation time. For problems with experimental data available, the accuracy of results generated by Serpent and AGREE is comparable to results obtained by other benchmark participants. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2022

Progress Towards A Measurement of Neutrino Induced Charged Current Neutral Pion Production in the MicroBooNE Experiment

An analysis of MicroBooNE data with a signal of one muon, one neutral pion, and no charged pions is presented. Studying neutral pion production in the MicroBooNE detector provides an opportunity to better understand neutrino-argon interactions, and is crucial for future accelerator-based neutrino oscillation experiments. This analysis presents the progress towards the first measurement of the differential cross section for charged current (CC) $π^0$ production in neutrino-argon interactions. Using a dataset corresponding to about 7 × 10 20 protons on target (POT), we present an analysis which aims to measure the single differential cross sections as a function of the $π^0$ kinematic variables such as momentum and scattering angle. The Wiener-SVD technique for unfolding the measurement is presented and demonstrated using multiple generator predictions. A future iteration of this analysis will compare an unfolded data measurement to these models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2026

Charged Pion Production Explorations Using the NOvA Near Detector

Measurements of neutrino-nucleus interactions in the few-GeV region provide crucial inputs to the neutrino oscillation program being carried out by currently running experiments (NOvA, SBN, T2K), and next-generation experiments (DUNE, 2HK). This poster presents the status of a measurement using the high-intensity NuMI beam and the NOvA Near Detector of the flux-integrated differential cross-section in pion kinetic energy for $\nu_\mu + N \rightarrow \mu^- + \pi^\pm + X$, where X does not include any charged pions. This signal is sensitive to inelastic processes with Delta resonance production, which dominate at neutrino energies relevant for NOvA and DUNE. To overcome the difficulty of reconstructing the energy of charged pions in a lower-spatial-resolution detector, a novel analysis technique is used that incorporates a multi-template fit to extract the number of events for two signal categories that differ from one another by their purity and resolution. The two signal categories are combined leveraging their complementary errors into a more informative cross section result.

Ewart, Erin [Indiana U.]↗

NASA NTRS1980

An ultrasonic plethysmograph for space flight applications

The development of an ultrasonic plethysmograph based on the transit time measurement principle is reported, which meets the space-imposed requirements for evaluating cardiovascular deconditioning. It consists of a pulse generator, pulse receiver amplifier, voltage comparator, synchronous pulse generator, elapsed time counter, and transmit and receive piezoelectric crystals resonant at 2 MHz and of 3 mm diameter. The transit time for an ultrasonic pulse to propagate across a limb cross section is computed in a digital fashion using a 32 MHz clock, and resolution is 0.049 mm with the range being approximately 200 mm. Experimental results regarding dynamic system response were found comparable in both accuracy and sensitivity to those of a Whitney strain gage using a 50 torr venous occlusion.

Bhagat, P. K.↗

NASA NTRS1984

A current generation by Compton scattering in a relativistic plasma with velocity shear and temperature gradient

Current generation by Thomson scattering in a non-relativistic plasma with the velocity shear and the temperature gradient (Hinata and Daneshvar, 1983) is extended to a relativistic plasma by replacing Thomson cross section by the Klein-Nishina formula. Because of the energy dependence of the cross-section, a numerical rather than analytic result is presented. The present calculation may be applied to a supernova implosion where the temperature may reach several MeV and a strong differential rotation is expected. It may also find applications in the early universe, and laser-pellet interaction.

Hinata, S.↗

NASA NTRSDate not supplied

Alignment and Verification Testing of the GPS LRA Test Bed

The LRCTF (Laser Ranging Characterization and Test Facility) is a unique facility built at NASA GSFC to provide thermal-optical testing of the next generation GPS LRA (Global Positioning Satellite’s Laser Retroreflector Array) laser ranging target. The 400mm diameter target is an array consisting of 48 total internal reflection retroreflectors and has an optical cross section requirement of 100 MSM (million square meters). To verify that the array meets this requirement during on-orbit conditions, the LRCTF is equipped with a 400mm test beam, a data product output consisting of full aperture FFDPs (Far Field Diffraction Patterns) and a thermal chamber. The FFDPs are used to calculate the OCS. This paper will describe the facility design, alignment approach, and verification process.

Patricia Lyons↗

NASA NTRSDate not supplied

Fluidic Fence Flow Control on A 30° Swept Wing in Compressible Freestreams

A 30° swept wing with a NACA 64(3)-618 airfoil cross-section was evaluated in four different freestream conditions with Mach numbers increasing from 0.05 to 0.7 using computational fluid dynamics simulations. Active flow control (AFC) through a streamwise row of vortex generating jets was applied at 70% span, blowing inboard to obstruct the development of spanwise flow and increase lift outboard of the control location. The effectiveness of the AFC was evaluated at α = 5° and 10° as freestream Mach number increased and the AFC mass flow coefficient was held constant. Increases to lift coefficient were reduced at higher Mach numbers, but the ratio of change in lift coefficient and the AFC momentum coefficient remained roughly constant. The fluidic fence caused decreased pressure coefficients on the outboard wing sections, but this region of decreased pressure coefficient moved aft on the chord with increasing Mach number. Mach 0.7 is higher than the critical Mach number of the wing and produced interesting interplay with the AFC, as the suction surface shock moved forward on the inboard wing section but moved aft on the outboard wing section.

Evan J McFadden↗

NASA NTRSDate not supplied

Fluidic Fence Flow Control on A 30° Swept Wing in Compressible Freestreams

Evan J McFadden↗

DOE OSTI2022

The LLNL nuclear data infrastructure for the GNDS data format

The next generation of nuclear data infrastructure tools at the Livermore National Laboratory (LLNL) consists of pipeline of codes that read and process nuclear data from evaluated files saved in the new GNDS (Generalised Nuclear Data Structure) nuclear data format. The processing code FUDGE (For Updating Data and Generating Evaluations) is at the front-end of this pipeline as it reads and process the evaluated data for use in downstream transport codes. FUDGE is Python based with C and C++ extensions for computationally intensive tasks. As is the case for the evaluated data, the processed output is also saved in the GNDS format and the GIDI+ API is provided as the interface between the processed data and the transport codes. GIDI+ is a C++ based suite of codes and it includes GIDI (General Interaction Data Interface), a library for reading and writing GNDS data, and MCGIDI which is the cross section lookup, and reaction and product distribution sampling interface between Monte Carlo transport codes and the GNDS data. GIDI provides methods for easy access to the multi-group processed GNDS data and this is demonstrated through its implementation in ARDRA, the LLNL deterministic transport code. The evaluation and sampling methods in MCGIDI are available as both CPU and GPU methods which facilitates the use of MCGIDI in both traditional CPU-based as well as the next generation mixed model computational architectures. This is demonstrated through the GIDI+ implementation in MERCURY, the LLNL Monte Carlo transport code. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2025

Search for electroweak production of vector-like leptons in $\tau$-lepton and b-jet final states in pp collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

A search for pair-production of vector-like leptons is presented, considering their decays into a third-generation Standard Model (SM) quark and a vector leptoquark ( U 1 ) as predicted by an ultraviolet-complete extension of the SM, referred to as the ‘4321’ model. Given the assumed decay of U 1 into third-generation SM fermions, the final state can contain multiple τ-leptons and b-quarks. This search is based on a dataset of pp collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of up to $140~\textrm{fb}^{-1}$. No significant excess above the SM background prediction is observed, and 95% confidence level limits on the cross-section times branching ratio are derived as a function of the vector-like lepton mass. A lower observed (expected) limit of 910 GeV (970 GeV) is set on the vector-like lepton mass. Additionally, the results are interpreted for a supersymmetric model with an R-parity violating coupling to the third-generation quarks and leptons. Lower observed (expected) limits are obtained on the higgsino mass at 880 GeV (940 GeV) and on the wino mass at 1170 GeV (1170 GeV).

Aad, G. [CPPM, Aix-Marseille Université, CNRS/IN2P↗

NASA NTRS1994

The Monostatic/Bistatic Approximation

Many Radar Cross Section (RCS) prediction codes are limited to one monostatic return per run. However, such codes can calculate multiple bistatic returns per incident angle for a relatively small amount of additional computer resources. This note describes a method of using bistatic returns to generate multiple monostatic predictions for each incident angle computed. Typical results are presented and show the accuracy is initially good and then degrades as the separation angle between the incident and viewing angles becomes large. Introduction Since 1990, the monostatic/bistatic approximation has been used to reduce the number of runs required by finite-volume time-domain (FVTD) codes for making RCS versus azimuth plots. This approximation was spawned by the observation of a range test where the transmit and receive antennas were separated by a few degrees to prevent cross talk between the antennas. The measurements from this range are presented as monostatic RCS rather than bistatic: RCS. The procedure of reporting experimental bistatic RCS as the monostatic RCS at the angle bisecting the transmit and receive antennas was extended to FVTD codes and produces excellent results.

Schuh, Michael J.↗

NASA NTRS1991

Interaction of two glancing, crossing shock waves with a turbulent boundary-layer at various Mach numbers

A preliminary experimental investigation was conducted to study two crossing, glancing shock waves of equal strengths, interacting with the boundary-layer developed on a supersonic wind tunnel wall. This study was performed at several Mach numbers between 2.5 and 4.0. The shock waves were created by fins (shock generators), spanning the tunnel test section, that were set at angles varying from 4 to 12 degrees. The data acquired are wall static pressure measurements, and qualitative information in the form of oil flow and schlieren visualizations. The principle aim is two-fold. First, a fundamental understanding of the physics underlying this flow phenomena is desired. Also, a comprehensive data set is needed for computational fluid dynamic code validation. Results indicate that for small shock generator angles, the boundary-layer remains attached throughout the flow field. However, with increasing shock strengths (increasing generator angles), boundary layer separation does occur and becomes progressively more severe as the generator angles are increased further. The location of the separation, which starts well downstream of the shock crossing point, moves upstream as shock strengths are increased. At the highest generator angles, the separation appears to begin coincident with the generator leading edges and engulfs most of the area between the generators. This phenomena occurs very near the 'unstart' limit for the generators. The wall pressures at the lower generator angles are nominally consistent with the flow geometries (i.e. shock patterns) although significantly affected by the boundary-layer upstream influence. As separation occurs, the wall pressures exhibit a gradient that is mainly axial in direction in the vicinity of the separation. At the limiting conditions the wall pressure gradients are primarily in the axial direction throughout.

Hingst, Warren R.↗

DOE OSTI2024

Measurement of t -channel production of single top quarks and antiquarks in pp collisions at 13 TeV using the full ATLAS Run 2 data sample

The production of single top quarks and top antiquarks via the t-channel exchange of a virtual W boson is measured in proton-proton collisions at a centre-of-mass energy of 13 TeV at the LHC using 140 fb -1 of ATLAS data. The total cross-sections are determined to be σ(tq) = 137$^{+8}_{-8}$ pb and σ($\bar{t}q$) = 84$^{+6}_{-5}$ pb for top-quark and top-antiquark production, respectively. The combined cross-section is found to be σ(tq + $\bar{t}q$) = 221$^{+13}_{-13}$ pb and the cross-section ratio is R t = σ(tq) / σ($\bar{t}q$) = 1.636$^{+0.036}_{-0.034}$. The predictions at next-to-next-to-leading-order in quantum chromodynamics are in good agreement with these measurements. The predicted value of R t using different sets of parton distribution functions is compared with the measured value, demonstrating the potential to further constrain the functions when using this result in global fits. The measured cross-sections are interpreted in an effective field theory approach, setting limits at the 95% confidence level on the strength of a four-quark operator and an operator coupling the third quark generation to the Higgs boson doublet: -0.37 < C$^{3,1}_{Qq}$ /Λ 2 < 0.06 and -0.87 < C$^{3}_{ΦQ}$ / Λ 2 < 1.42. The constraint |V tb | > 0.95 at the 95% confdence level is derived from the measured value of σ(tq + $\bar{t}q$), assuming that the Wtb interaction is a left-handed weak coupling and that |V tb | $\gg$ |V td |, |V ts |. In a more general approach, pairs of CKM matrix elements involving top quarks are simultaneously constrained, leading to confdence contours in the corresponding two-dimensional parameter spaces.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Full treatment of the thrust distribution in single inclusive e + e – → h X processes

Extending the transverse momentum dependent factorization to thrust dependent observables entails a series of difficulties, ultimately associated to the behavior of soft radiation. As a consequence, the definition of the transverse momentum dependent functions has to be revised, while preserving (and possibly extending) their universality properties. Moreover, the regularization of the rapidity divergences generates non trivial correlations between rapidity and thrust. In this paper, we show how to deal with these correlations in a consistent treatment of the thrust dependence of e + e – → h X cross section, where the hadron transverse momentum is measured with respect to the thrust axis. In this framework all results obtained in the past few years properly fit together, leading to a remarkable phenomenological description of the experimental measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2022

Development of 17 N as a time-tagged neutron source for calibration of large antineutrino detectors

Large antineutrino detectors hold the potential for remote nuclear reactor monitoring and discovery, which is of great interest for nonproliferation and treaty verification applications. Correlated-particle calibration sources are especially useful for large-volume designs based on detection of inverse beta-decay events, as the timing information of the coincident particles improves background rejection and event reconstruction. 17 N is a promising calibration source since it emits beta-correlated delayed neutrons and can be produced relatively easily using high-energy neutrons. In this work, we examine the feasibility of 17 N as a time-tagged calibration source for large antineutrino detectors. 17 N was produced using a DT neutron generator from a water sample enriched in 17 O, and the observed production rates were found to be consistent with previous measurements of the 17 O(n,p) 17 N reaction cross-section. As a result, time-tagging of 17 N delayed neutrons is demonstrated via beta-neutron coincidence measurements conducted using a specialized beta detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2022

Bayesian estimation of the $S$ factor and thermonuclear reaction rate for 16 O(p, γ) 17 F

The 16 O(p, γ) 17 F reaction is the slowest hydrogen-burning process in the CNO mass region. Its thermonuclear rate sensitively impacts predictions of oxygen isotopic ratios in a number of astrophysical sites, including AGB stars. The reaction has been measured several times at low bombarding energies using a variety of techniques. The most recent evaluated experimental rates have a reported uncertainty of about 7.5% below 1 GK. However, the previous rate estimate represents a best guess only and was not based on rigorous statistical methods. We apply a Bayesian model to fit all reliable 16 O(p, γ) 17 F cross section data, and take into account independent contributions of statistical and systematic uncertainties. The nuclear reaction model employed is a single-particle potential model involving a Woods-Saxon potential for generating the radial bound state wave function. The model has three physical parameters, the radius and diffuseness of the Woods-Saxon potential, and the asymptotic normalization coefficients (ANCs) of the final bound state in 17 F. Here, we find that performing the Bayesian S -factor fit using ANCs as scaling parameters has a distinct advantage over adopting spectroscopic factors instead. Based on these results, we present the first statistically rigorous estimation of experimental 16 O(p, γ) 17 F reaction rates, with uncertainties (±4.2%) of about half the previously reported values.

6 ≤ A ≤ 19↗

DOE OSTI2024

Search for leptoquark pair production decaying into $te^- \bar{t}e^+$ or $t\mu ^- \bar{t}\mu ^+$ in multi-lepton final states in pp collisions at $\sqrt{s} = 13\,\textrm{TeV}$ with the ATLAS detector

A search for leptoquark pair production decaying into $te^- \bar{t}e^+$ or $t\mu ^- \bar{t}\mu ^+$ in final states with multiple leptons is presented. The search is based on a dataset of pp collisions at $\sqrt{s}=13~\text {TeV}$ recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb -1 . Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from a b-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into $te^{-}$ ($t\mu ^{-}$ ), the corresponding lower limit on the scalar mixed-generation leptoquark mass $m_{\textrm{LQ}_{\textrm{mix}}^{\textrm{d}}}$ is at 1.58 (1.59) TeV and on the vector leptoquark mass $m_{{\tilde{U}}_1}$ at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang–Mills scenario.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2026

Thermal Compton Scattering of Electron Beams on Blackbody Photons: A Monte Carlo Event Generator for Multi-Turn Tracking at the Electron-Ion Collider

Compton scattering of ultra-relativistic electrons on thermal (blackbody) photons is typically a subdominant process in electron storage rings, but at sufficiently high electron energy and low residual gas pressure it can become competitive with beam-gas scattering and contribute to dis tributed losses and backgrounds. We present a self-contained Monte Carlo event generator for thermal Compton scattering designed for integration into multi-turn tracking workflows. The im plementation follows H. Burkhardt’s proposal method: trial scattering angles are sampled from the Thomson differential cross section and accepted/rejected using the Klein-Nishina to Thomson ratio, yielding the correct Compton spectrum while retaining simple absolute-rate normalization. Ther mal photon energies are sampled from the blackbody photon-number spectrum via an exact mixture representation.

43 PARTICLE ACCELERATORS↗