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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Asymptotic Normalization Coefficients (Nuclear Vertex Constants), Three-Body Asymptotic Normalization Functions (On-Shell Vertex Functions) and Nuclear Astrophysics

In the present review work, the main methods of the determination of asymptotic normalization coefficients (or respective nuclear vertex constants) for the A + x → B channel and of threebody asymptotic normalization functions (or respective on-shell vertex functions) for the A + b + c → B channel are briefly discussed. The main attention is paid both to the use of the specific asymptotic normalization coefficients and three-body asymptotic normalization functions as a source of getting the valuable information about the pair (nucleon–nucleon, nucleon–cluster and cluster–cluster) nuclear interactions and to their application for the specific direct nuclear-astrophysical radiative capture and peripheral transfer reactions at low energies.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Measurements of the L-shell X-ray emission of fluorine-like europium

Measurements of the L-shell X-ray emission of fluorine-like europium ions (Eu 54+ ) were made under controlled laboratory conditions on the EBIT-I electron beam ion trap at Livermore using an X-ray calorimeter, extending such measurements to the middle of the rare earth elements. Comparing the calorimeter spectra with atomic data from the flexible atomic code, we have identified and analyzed several prominent n = 3 → n = 2 transitions, including one two-electron, one-photon core changing transition and one electric quadrupole transition. We find that the measured energies are typically up to several eV higher than predicted.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2019

No-core shell model calculations of the photonuclear cross section of 10B

Results of ab initio no-core, shell model calculations for the photonuclear cross section of 10B are presented using realistic two-nucleon (NN) chiral forces up to next-to-next-to-next-order (N3LO) softened by the similarity renormalization group method (SRG) with λ=2.02 fm -1 . The electric-dipole response function is calculated using the Lanczos method, with the effects of the continuum included via neutron escape widths derived from R-matrix theory and using the Lorentz integral transform method. The calculated cross section agrees well with experimental data in terms of structure as well as in absolute peak height, σ max =4.85 mb at photon energy ω=23.61 MeV, and integrated cross section 85.36 MeV. mb. We also test the Brink hypothesis by calculating the electric-dipole response for the first nine positive-parity states with J≠0 in 10 B and verify that dipole excitations built upon the ground and excited states have similar characteristics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Leveraging on-shell interference to search for FCNCs of the top quark and the Z boson

Abstract Flavour-changing-neutral currents (FCNCs) involving the top quark are highly suppressed within the Standard Model (SM). Hence, any signal in current or planned future collider experiments would constitute a clear manifestation of physics beyond the SM. We propose a novel, interference-based strategy to search for top-quark FCNCs involving the Z boson that has the potential to complement traditional search strategies due to a more favourable luminosity scaling. The strategy leverages on-shell interference between the FCNC and SM decay of the top quark into hadronic final states. We estimate the feasibility of the most promising case of anomalous tZc couplings using Monte Carlo simulations and a simplified detector simulation. We consider the main background processes and discriminate the signal from the background with a deep neural network that is parametrised in the value of the anomalous tZc coupling. We present sensitivity projections for the HL-LHC and the FCC-hh. We find an expected 95% CL upper limit of $${\mathcal {B}}_{\textrm{excl}}(t\rightarrow Zc) = 6.4 \times 10^{-5}$$ B excl ( t → Z c ) = 6.4 × 10 - 5 for the HL-LHC. In general, we conclude that the interference-based approach has the potential to provide both competitive and complementary constraints to traditional multi-lepton searches and other strategies that have been proposed to search for tZc FCNCs.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

SD-pair shell model: Vibrational and rotational limits in the interacting boson–fermion model for like-nucleon system

Typical features of the Bose–Fermi symmetries associated with [Formula: see text] and [Formula: see text] limits in the interacting boson model are described in the SD-pair shell model (SDPSM) framework for like-nucleon system. It is found that the limiting spectra associated with [Formula: see text] (vibrational) and [Formula: see text] (rotational) in the interacting boson–fermion model can be well reproduced in the SDPSM framework. It is shown that coupling of collective degree of freedom with the single-particle degree of freedom in the pairing interaction almost has no effect on the spectrum of odd-A system comparing to the adjacent even–even system, while the coupling of the collective degree of freedom with the single-particle degree of freedom in the quadrupole–quadrupole interaction results in the level splitting of several excited levels.

Physics↗
DOE OSTI2018

Enhanced Oxygen Reduction Reaction Activity on Pt-Monolayer-Shell PdIr/Ni-Core Catalysts

Platinum monolayer oxygen reduction reaction catalysts offer the most promising possibility of reducing the Pt content without sacrificing its fuel cell performance. Here, we present a facile way of preparing Pt monolayer shell on PdIr-based core catalysts with and without Ni sub-core. They showed much higher activity for oxygen reduction reaction than commercial Pt/C catalyst. Among tested samples, PtMLPd2Ir/Ni/C performs the best having Pt mass activity 14 times and Platinum Group Metal mass activity 0.8 times higher than that of Pt/C. In addition, accelerated durability test indicates its excellent durability, which was demonstrated by a 7.5% decrease in Platinum Group Metal mass activity compared to 64% for the commercial Pt/C catalyst. As a result, the role of Ni sub-core in oxygen reduction reaction activity and durability of PtML on PdIr-based catalysts was also elucidated.

25 ENERGY STORAGE↗
DOE OSTI2020

Pseudoscalar pair production via off-shell Higgs in composite Higgs models

We propose a new type of search for a pseudoscalar particle $\eta$ pair produced via an off-shell Higgs, $pp$ → $h*$ → $\eta\eta$. The search is motivated by a composite Higgs model in which the $\eta$ is extremely narrow and decays almost exclusively into Z in the mass range 65 $\lesssim$ GeV $m_{\eta}$ $\lesssim$ 160 GeV. We devise an analysis strategy to observe the novel Zγ Zγ channel and estimate potential bounds on the Higgs-$\eta$ coupling. The experimental sensitivity to the signatures depends on the power to identify fake photons and on the ability to predict large photon multiplicities. This search allows us to exclude large values of the compositeness scale $f$, being thus complementary to other typical processes.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Single-Shell Tank Structural Integrity Assessment Report

Integrity assessments are required to determine that the existing single-shell tanks (SST) located at the Hanford Site have structural integrity such that they will not collapse, rupture, or fail. This is a requirement of the Hanford Federal Facility Agreement and Consent Order Tri-Party Agreement (TPA)1 Change Request M-45-10-01 which established SST Integrity Project interim milestones and targets in January 2011. Interim Milestone M-045-91I established the requirement for this SST structural integrity assessment to be completed with an Independent Qualified Registered Professional Engineer (IQRPE) certification by September 30, 2018.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Stable Perovskite Core-Shell Nanocrystals as Down-Converting Phosphors for Solid State Lighting

Colloidal perovskite quantum dots (QDs) or nanocrystals (NCs) with structure of CsPbX 3 (X = Cl, Br, I) are promising materials as down-converting phosphors due to their high quantum yield up to >90%, extremely narrow emission band ~15-30 nm, and tunable emission wavelengths of ~410-700 nm via size or composition control. Compared to other QD materials, the optical and electronic properties of perovskite NCs are much more tolerant to defects so highly efficient light-emitting NCs can be easily prepared without carefully removing surface defects. Also, precision size control is not required for obtaining perovskite NCs with narrow emission <30 nm and can greatly enhance the reproducibility and yield rate during mass production. The challenges in using perovskite NCs as LED phosphors are their hygroscopic nature and self-absorption as observed from other QDs. We propose to synthesize core-shell structure perovskite NCs to improve their stability by over-coating a SiO 2 layer, followed by further sol-gel processing into stable micro-sized glass beads. To increase Stokes shift and avoid self-absorption, core/graded-shell/shell structure such as CsSnBr 3 /CsSn 1-x Pb x Br 3 /CsPbBr 3 NCs will be prepared, similar to a concept we demonstrated before in CdSe/Cd 1-x ZnxSe 1-y S y /ZnS structure with significantly separated absorption and emission bands. These NC materials will be integrated into films and used as remote or on-chip downconverters for high efficiency, high CRI and warm white LED. To achieve this goal, PhosphorTech Corporation (PTC) has teamed with Georgia Tech (GT) to develop this unique perovskite system for pcLEDs that offers the promise of high luminous efficacy over a broad temperature and optical flux range.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Hanford Double Shell Waste Tank Corrosion Studies (Final Report FY2018)

For FY18, Savannah River National Laboratory (SRNL) focused on four main tasks in its study of corrosion of Hanford Double-Shell Tanks (DSTs). The New Limits task focused on the development of a pitting factor as a localized corrosion predictor. Electrochemical experiments were directed towards pitting factors between 1 and 2 (i.e., borderline conditions) and separating the effects of chloride and fluoride in the pitting factor equation. In addition, long term immersion testing experiments with partial and completely immersed coupons in solutions with a wide range of pitting factors were tested. Secondary liner studies continued this year with a new vapor corrosion inhibition (VCI) strategy in which ground water (GW) simulants at a specified concentration of commercial VCI were mixed. The specific concentrations were recommended by Cortec® and was compared with similar concentration of GW with calcium carbonate. The anodic drift task utilized a simulant corresponding to AN-107 waste tank chemistry. The chemistry was studied with three different surface conditions: mill-scale, partial mill-scale and ground to 600 grit to study the impact of different surfaces on the potential drift. The final task was focused on ammonia concentration determination of a vapor space corrosion (VSC) test vessel using Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) detector. A summary of each task is presented below.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Hanford Double Shell Waste Tank Corrosion Studies (Final Report FY2019)

During fiscal year (FY) 2019, the Savannah River National Laboratory (SRNL) focused on four primary tasks for Hanford Double Shell Tanks (DSTs) corrosion studies. The first task, New Limits, was a continuation from the electrochemical work started in FY16, to expand electrochemical testing to elevated temperatures and elevated hydroxide concentrations and evaluate how these factors will influence pitting corrosion. Using the pitting factor (PF) equation, these new conditions were validated to provide a conservative estimate for the susceptibility of pitting corrosion on legacy carbon steel. The second task, Secondary Liner Corrosion, focused on Vapor Space Corrosion (VSC) and immersion testing studies using two commercially available vapor corrosion inhibitors (VCIs). For this FY, the VCI strategy was applied mid-experiment to determine performance on weathered coupons. The third task, Long-Term Open Circuit Potential (OCP) Drift, was performed using simplified simulated chemistries to evaluate change in pitting corrosion risk due to evolution of corrosion potential for mill-scale and freshly polished 600-grit surfaces. Finally, the fourth task, Microbiologically-Influenced Corrosion (MIC) studies, was focused on the study of leak detection pit (LDP) water sent from the Hanford tank farm for determination of bacteria that can be conducive to corrosion using commercially available kits: BART TM and MICkit® 5. In addition, this FY, a secondary task was added which was a continuation of the study of the Quartz-enhanced Photoacoustic Spectroscopy (QEPAS) system. Work was started but was ultimately not pursued. A summary of each task performed is presented below.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Variational calculation of closed-shell nuclei up to A=40 [Slides]

Compute ground state properties of closed-shell nuclei up to A = 40 with quantum Monte Carlo. Analyze the behavior of phenomenological Hamiltonians in medium-heavy nuclei. Study the high-momentum components of the nuclear wave function and potential in-medium modifications of the nucleon form factors.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

The Snell's Law Shell Ionospheric Transfer Function

Ionospheric transfer function (ITF) algorithms determine the effects of the ionosphere on an electromagnetic (EM) radio-frequency (RF) signal as it propagates through. In this report, the Snell’s law shell (slab) model is outlined.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Hanford Double Shell Waste Tank Corrosion Studies FY2020 (Final Report)

For fiscal year (FY) 2020, the Savannah River National Laboratory (SRNL) focused on three experimental tasks related to Hanford Double Shell Tank (DST) chemistry and integrity. The first task focused on understanding risk of corrosion due to formation of either continuous layers or discrete patches of deposits on the tanks’ inner sidewalls and bottoms. The second task studied vapor space corrosion (VSC) of the secondary liner using two commercially available vapor corrosion inhibitors (VCIs) at manufacturer recommended dosages. Finally, the third task investigated the long-term open circuit potential (OCP) drift for mill-scale coupons, coupons with polished surfaces, and partial mill-scale coupons that were exposed to tank waste simulants. Additional tests were performed to evaluate the OCP drift as a function of the quantity and composition of organic compounds added to the simulant. A test that was included in the matrix that established the new chemistry limits for tank corrosion, but was previously unreported, was presented and reviewed as well.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Hanford Double Shell Waste Tank Corrosion Studies (Final Report FY2021)

For fiscal year (FY) 2021, the Savannah River National Laboratory (SRNL) focused on two experimental tasks related to Hanford Double Shell Tank (DST) chemistry and integrity. The first task focused on understanding risk of corrosion due to formation of either continuous layers or discrete patches of deposits on the tanks’ inner sidewalls and bottoms. The second task studied vapor space corrosion (VSC) inhibition of the secondary liner using vapor corrosion inhibitors (VCIs) at dosages less than the manufacturer recommended and a control test in which no VCIs were added.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Overview of the LANL Double Shell Campaign [Slides]

A volume burning ignition target allows for high temperature with comparitvely lower areal density. The large number of interfaces allows for a deep investigation of the impact of hydrodynamic instabilities on implosion quality. Machine learning is currently being leveraged to improve the quality of the design. Due to the presence of high-z material we must take a deeper level of hohlraum physics into account compared to single shell designs.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Improving the probability tables of the cross section of near closed-shell nuclei [Slides]

The level density distribution of near closed-shell nuclei is much lower than the typical nucleus, therefore, the cross sections show significant fluctuations, and these fluctuations are not predictable. The current methodology used to describe such behavior and construct the probability table of the cross section is based on the extrapolation of the average resonance widths and average resonance spacings from the resonance region and use these parameters to construct the probability table. Although this is a standard and widely used technique, it does not take into account the existing experimental data, such for total and the elastic cross section. Our goal is to extend the current theory and provide a more general approach to compute the probability distribution function of the cross section combining the existing probability tables and the available experimental data. Results will be presented for 90 Zr.

07 ISOTOPE AND RADIATION SOURCES↗