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All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Morphological and Surface Structural Changes during Electrochemical Cycling in Li-rich Layered Oxides for Next Generation Li-ion Batteries

Li-rich layered oxides, either as a solid solution or as a nano-composite of layered Li 2 MnO 3 and Li(TM)O 2 (TM=Ni, Co, Mn), draw significant attention as the next-generation cathode materials for high-energy-density Li-ion batteries in electric vehicles. However, there are many issues still unclear, and numerous scientific challenges of these materials that must be overcome to realize their utilization in commercial Li-ion batteries. The first drawback is the irreversible voltage degradation process that limits cycle life. Modified co-precipitation synthesis is introduced to obtain morphology controlled Li-rich material without ammonia addition. This unique design increases meso-structure morphological stability compared with the sample with large secondary particles as proved by Transmission X-ray Microscope. As a result, the voltage decay and capacity loss during long term cycling have been minimized to a large extent. On the other hand, lattice oxygen plays an intriguing role in the electrochemical process of Li-rich material through a reversible redox process as well as an irreversible oxidation with O 2 gas release. To prevent oxygen gas generation, oxygen vacancies have been proposed to form on the surface of the morphology controlled Li-rich layered oxides through the design of a gas-solid interface reaction (GSIR). Dynamic structural changes during the initial two electrochemical cycles of GSIR Li-rich layered oxides are investigated with In operando synchrotron X-ray diffraction (SXRD). Different electrochemical reaction regions dominated by either cations or anions redox are identified in the shifts of the lattice parameters during the first cycle. Changes in lattice parameters, oxygen positions, and microstrain help to explain the lithium de-intercalation mechanism in this class of materials.

Zhang, Minghao↗
DOE OSTI2025

Gamma Decay of the 154 Sm Isovector Giant Dipole Resonance: Smekal-Raman Scattering as a Novel Probe of Nuclear Ground-State Deformation

𝛾 decays of the isovector giant dipole resonance (IVGDR) of the deformed nucleus 154 Sm were measured using 2$^{+}_{1}$-Smekal-Raman and elastic scattering of linearly polarized, quasimonochromatic photon beams. The two scattering processes were disentangled through their distinct angular distributions. Their branching ratio and cross sections were determined at six excitation energies covering the 154 Sm IVGDR. Both agree with the predictions of the geometrical model for the IVGDR and confirm 𝛾 decay as an observable sensitive to the structure of the resonance. Consequently, the data place strong constraints on the nuclear shape, including the degree of triaxiality. The derived 154 Sm shape parameters 𝛽 = 0.2925⁢(25) and 𝛾 = 5.0⁢(15)° agree well with other measurements and recent Monte Carlo shell-model calculations.

150 ≤ A ≤ 189↗
DOE OSTI2012

NLO Vector Boson Production With Light Jets

In this contribution we present recent progress in the computation of next-to-leading order (NLO) QCD corrections for the production of an electroweak vector boson in association with jets at hadron colliders. We focus on results obtained using the virtual matrix element library BlackHat in conjunction with SHERPA, focusing on results relevant to understanding the background to top production. The production of a vector boson in association with several jets at the Large Hadron Collider (LHC) is an important background for other Standard Model processes as well as new physics signals. In particular, the production of a W boson in association with many jets is an important background for processes involving one or more top quarks. Precise predictions for the backgrounds are crucial to measurement of top-quark processes. Vector boson production in association with multiple jets is also a very important background for many SUSY searches, as it mimics the signatures of many typical decay chains. Here we will discuss how polarization information can be used as an additional handle to differentiate top pair production from 'prompt' W-boson production. More generally, ratios of observables, for example for events containing a W boson versus those containing a Z boson, are expected to be better-behaved as many uncertainties cancel in such ratios. Precise calculation of ratios, along with measurement of one of the two processes in the ratio, can be used in data-driven techniques for estimating backgrounds.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Radiopurity assessment of the energy readout for the NEXT double beta decay experiment

In this study, the "Neutrino Experiment with a Xenon Time-Projection Chamber" (NEXT) experiment intends to investigate the neutrinoless double beta decay of 136 Xe, and therefore requires a severe suppression of potential backgrounds. An extensive material screening and selection process was undertaken to quantify the radioactivity of the materials used in the experiment. Separate energy and tracking readout planes using different sensors allow us to combine the measurement of the topological signature of the event for background discrimination with the energy resolution optimization. The design of radiopure readout planes, in direct contact with the gas detector medium, was especially challenging since the required components typically have activities too large for experiments demanding ultra-low background conditions. After studying the tracking plane, here the radiopurity control of the energy plane is presented, mainly based on gamma-ray spectroscopy using ultra-low background germanium detectors at the Laboratorio Subterr'aneo de Canfranc (Spain). All the available units of the selected model of photomultiplier have been screened together with most of the components for the bases, enclosures and windows. According to these results for the activity of the relevant radioisotopes, the selected components of the energy plane would give a contribution to the overall background level in the region of interest of at most 2.4×10 –4 counts keV –1 kg –1 y –1 , satisfying the sensitivity requirements of the NEXT experiment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Lyman-α constraints on cosmic heating from dark matter annihilation and decay

We derive new constraints on models of decaying and annihilating dark matter (DM) by requiring that the energy injected into the intergalactic medium (IGM) not overheat it at late times, when measurements of the Lyman-α forest constrain the IGM temperature. We improve upon previous analyses by using the recently developed DarkHistory code package, which self-consistently takes into account additional photoionization and photoheating processes due to reionization and DM sources. Our constraints are robust to the uncertainties of reionization and competitive with leading limits on sub-GeV DM that decays preferentially to electrons

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Fluorination effect for stabilizing cationic and anionic redox activities in cation-disordered cathode materials

We see that cation-disordered Li-excess cathodes with oxygen redox reactions are promising candidates for high-energy-density Li ion batteries. Nevertheless, the oxygen redox process that is required for the high capacity often comes with the oxygen loss, which leads to severe capacity degradation and voltage decay. In this work, we have successfully synthesized a series of Li-excess cation-disordered cathodes (Li 1.2 Mn 0.4+x Ti 0.4-x O 2-x Fx) (0 ≤ x ≤ 0.2) with different fluorine (F) contents. The electrochemical performance results show that the Li 1.2 Mn 0.55 Ti 0.25 O 1.85 F 0.15 (LMTOF0.15) exhibits the highest reversible capacity (275 mAh g -1 , under 30 mA g -1 ), cyclability, and voltage retentions. The mapping of resonant inelastic X-ray scattering (mRIXS) and differential electrochemical mass spectroscopy (DEMS) results reveal that the fluorination enhances the reversible lattice oxygen redox reaction while suppressing irreversible gas release and surface reactions. The X-ray Absorption Spectroscopy (XAS) during the initial two cycles shows that F-substitution alleviates the reduction of the Mn valence state during the whole (dis)charge processes in the bulk and at the surface of the material, results in higher average discharge voltage. In addition, the introduction of F improves the structural stability and suppresses local lattice distortion of the material. Therefore, LMTOF 0.15 is able to cycle with smaller polarization, less interfacial side reaction and Mn dissolution, and therefore results in enhanced cyclability. This work provides a comprehensive understanding of the fluorination effect on the cationic and anionic redox activities in cation-disordered Li-excess cathodes.

25 ENERGY STORAGE↗
DOE OSTI2020

Iodine Effects on Medical Isotope Producer Delay & Guard Bed Temperature and Performance in Support of NA-23 Program

In support of NA-23’s objective to accelerate the establishment of a reliable commercial United States (U.S.) domestic supply of 99Mo produced without the use of highly enriched uranium (HEU), the Pacific Northwest National Laboratory (PNNL) was tasked with modeling the performance of activated carbon delay and guard beds that may be typical for non-HEU 99Mo production processes. The specific tasks accomplished by PNNL included calculations of long-term effects of iodine on delay bed performance and development of a finite element simulation to better understand delay bed performance under various scenarios specifically with radioxenon and radioiodine decay heating of the delay beds. The main issue of interest in this study is understanding the effect of iodine on the abatement performance of the beds if iodine is not sufficiently removed from gases prior to reaching the delay beds. Finite element simulations of delay bed performance were developed using COMSOL Multiphysics® Software. These simulations are based on partial differential equations that describe xenon and iodine adsorption, heat transfer and decay of radioxenon and radioiodine isotopes. Heat transfer in the activated carbon beds is simulated with a heat source tied to the decay of radioactive xenon and iodine species. These simulations were used to investigate delay bed temperature and hold up time using radioxenon and radioiodine activities and flowrates expected from a non-HEU production process. A bounding case scenario was simulated, where all the iodine was released into the delay beds due to insufficient guarding of the delay beds. In addition, preliminary investigations of the guard beds were conducted.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2022

CUPID: The Next-Generation Neutrinoless Double Beta Decay Experiment

We report CUPID is a next-generation tonne-scale bolometric neutrinoless double beta decay experiment that will probe the Majorana nature of neutrinos and discover lepton number violation in case of observation of this singular process. CUPID will be built on experience, expertise and lessons learned in CUORE and will be installed in the current CUORE infra-structure in the Gran Sasso underground laboratory. The CUPID detector technology, successfully tested in the CUPID-Mo experiment, is based on scintillating bolometers of Li 2 MoO 4 enriched in the isotope of interest 100 Mo. In order to achieve its ambitious science goals, the CUPID collaboration aims to reduce the backgrounds in the region of interest by a factor 100 with respect to CUORE. This performance will be achieved by introducing the high efficient α/β discrimination demonstrated by the CUPID-0 and CUPID-Mo experiments, and using a high transition energy double beta decay nucleus such as 100 Mo to minimize the impact of the gamma background. CUPID will consist of about 1500 hybrid heat-light detectors for a total isotope mass of 250 kg. The CUPID scientific reach is supported by a detailed and safe background model based on CUORE, CUPID-Mo and CUPID-0 results. The required performances have already been demonstrated and will be presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Search for exotic resonances decaying into WZ/ZZ in pp collisions at $ \sqrt{s}=7 $ TeV

A search for new exotic particles decaying to the VZ final state is performed, where V is either a W or a Z boson decaying into two overlapping jets and the Z decays into a pair of electrons, muons or neutrinos. The analysis uses a data sample of pp collisions corresponding to an integrated luminosity of 5 fb -1 collected by the CMS experiment at the LHC at TeV in 2011. No significant excess is observed in the mass distribution of the VZ candidates compared with the background expectation from standard model processes. Model-dependent upper limits at the 95% confidence level are set on the product of the cross section times the branching fraction of hypothetical particles decaying to the VZ final state as a function of mass. Sequential standard model W' bosons with masses between 700 and 940 GeV are excluded. In the Randall-Sundrum model for graviton resonances with a coupling parameter of 0.05, masses between 750 and 880 GeV are also excluded.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Search for direct detection of thorium-229m nuclear VUV photons

We used two methods to attempt to measure the lifetime and energy level of the 229m Th low-lying nuclear state. Both methods used a 233 U source to implant 229 Th into a VUV transparent substrate. The uranium source had a low concentration of 232 U (0.08 ppm) and was chemically purified one week prior to the start of the experiment. In the first method, the time decay method, sensitive to 229m Th lifetimes from 10 min to 15 h, the VUV substrate was irradiated for 4–36 h to ensure a sufficient transfer of 229m Th ions into the substrate. Then the signal from the substrate was observed using a PMT for 15 h. A bandpass filter was placed between the substrate and PMT to provide a means of measuring the 229m Th photon energy. We used nine filters with center transmissions ranging from 140 to 244 nm. In the second method, direct detection, sensitive to lifetimes from zero to 10 min, the substrate was observed directly with the PMT and filter during the deposition process. For both methods our results were limited by the strong background fluorescence and phosphorescence due to the alphas and betas intrinsic to the decay of the 233 U and its daughters. We did not see unambiguous signs of photons from 229m Th. This may be due to one or more of the following: lifetime of 229m Th too short or too long, branching ratio to produce 229m Th from 233 U is too small, energy of 229m Th transition is outside of our observed range of 5.1–8.9 eV, and/or most likely, 229m Th ions drop to a +1 or 0 charge state, and thus lose their nuclear excitation through non-radiative processes.

229Th↗
DOE OSTI2020

The role of geography in the complex diffusion of innovations

The urban–rural divide is increasing in modern societies calling for geographical extensions of social influence modelling. Improved understanding of innovation diffusion across locations and through social connections can provide us with new insights into the spread of information, technological progress and economic development. In this work, we analyze the spatial adoption dynamics of iWiW, an Online Social Network (OSN) in Hungary and uncover empirical features about the spatial adoption in social networks. During its entire life cycle from 2002 to 2012, iWiW reached up to 300 million friendship ties of 3 million users. We find that the number of adopters as a function of town population follows a scaling law that reveals a strongly concentrated early adoption in large towns and a less concentrated late adoption. We also discover a strengthening distance decay of spread over the life-cycle indicating high fraction of distant diffusion in early stages but the dominance of local diffusion in late stages. The spreading process is modelled within the Bass diffusion framework that enables us to compare the differential equation version with an agent-based version of the model run on the empirical network. Although both model versions can capture the macro trend of adoption, they have limited capacity to describe the observed trends of urban scaling and distance decay. We find, however that incorporating adoption thresholds, defined by the fraction of social connections that adopt a technology before the individual adopts, improves the network model fit to the urban scaling of early adopters. Controlling for the threshold distribution enables us to eliminate the bias induced by local network structure on predicting local adoption peaks. Finally, we show that geographical features such as distance from the innovation origin and town size influence prediction of adoption peak at local scales in all model specifications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Neutrinos from Beta Processes in a Presupernova: Probing the Isotopic Evolution of a Massive Star

We present a new calculation of the neutrino flux received at Earth from a massive star in the ~24 hr of evolution prior to its explosion as a supernova (presupernova). Using the stellar evolution code MESA, the neutrino emissivity in each flavor is calculated at many radial zones and time steps. In addition to thermal processes, neutrino production via beta processes is modeled in detail, using a network of 204 isotopes. We find that the total produced ${\nu }_{e}$ flux has a high-energy spectrum tail, at $E\gtrsim 3\mbox{--}4\,\mathrm{MeV}$, which is mostly due to decay and electron capture on isotopes with $A=50\mbox{--}60$. In a tentative window of observability of $E\gtrsim 0.5\,\mathrm{MeV}$ and $t\lt 2$ hr pre-collapse, the contribution of beta processes to the ${\nu }_{e}$ flux is at the level of ~90%. For a star at D = 1 kpc distance, a 17 kt liquid scintillator detector would typically observe several tens of events from a presupernova, of which up to ~30% is due to beta processes. These processes dominate the signal at a liquid argon detector, thus greatly enhancing its sensitivity to a presupernova.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Modeling 233 Pa Generation in Thorium-fueled Reactors for Safeguards

Thorium has been considered as a possible alternative to uranium for nuclear fuel for many decades. It is three to four times more abundant in the earth than uranium and produces significantly less long-lived transuranic nuclear waste. Some claim thorium poses fewer proliferation concerns than other fuel types largely due to 232 U buildup (and associated high energy gamma-emitting decay products) in the irradiated thorium fuel. However, to fully explore potential proliferation concerns, generation and subsequent decay of 233 Pa produced in the reactor core still must be studied. With its half-life of 27 days, 233 Pa decays to 233 U, which is an International Atomic Energy Agency (IAEA) defined special fissionable material that can be used for nuclear weapons production. With more research being dedicated to thorium-fueled reactors, and several of these reactor designs possessing online fuel processing (allowing for on-site protactinium separation), it is important to understand this potential proliferation pathway. In particular, it is theoretically possible to extract protactinium from the irradiated fuel salt before it decays into 233 U. This hypothetical potential diversion can become an even greater proliferation concern if the extracted protactinium is purified through a second separation of protactinium approximately ten days later to remove the short half-life decay products of 232 Pa and 234 Pa, thus resulting in a higher concentration of the 233 Pa isotope, which decays into weapons usable 233 U with hardly any 232 U or 234 U in it. To estimate the concern of this potential proliferation challenge of thorium, different nuclear material accountancy techniques were reviewed for their viability to quantify 233 Pa if extracted from used thorium fuel. Characteristics of interest included technology maturity, cost, precision, and time taken to acquire results. Some technologies, like hybrid K-edge densitometry and passive gamma spectroscopy, appear to be viable techniques based on current literature. Due to the limited scope of this project, only passive gamma spectroscopy was further investigated. Three different reactor types (PWR, CANDU, MSR) were modeled with mixed thorium-uranium oxide fuels that were burned until the fuel was spent. The protactinium in the used fuel was extracted at the time of shutdown and the change in isotopic content of the protactinium quantified. Gamma spectroscopy simulations were performed for the protactinium isotopes and their decay products at various decay times. Given the simplicity of the models and large assumptions made (e.g. no background, no shielding, no self-attenuation), the initial results indicate that though 233 Pa is detectible for all the reactor types modeled at all decay times (0 to 300 days), more work should be done with higher fidelity models.

07 ISOTOPE AND RADIATION SOURCES↗
NASA NTRS1995

Overview of the preparation and use of an OV-10 aircraft for wake vortex hazards flight experiments

An overview is presented of the development, use, and current flight-test status of a highly instrumented North American Rockwell OV-10A Bronco as a wake-vortex-hazards research aircraft. A description of the operational requirements and measurements criteria, the resulting instrumentation systems and aircraft modifications, system-calibration and research flights completed to date, and current flight status are included. These experiments are being conducted by the National Aeronautics and Space Administration as part of an effort to provide the technology to safely improve the capacity of the nation's air transportation system and specifically to provide key data in understanding and predicting wake vortex decay, transport characteristics, and the dynamics of encountering wake turbulence. The OV-10A performs several roles including meteorological measurements platform, wake-decay quantifier, and trajectory-quantifier for wake encounters. Extensive research instrumentation systems include multiple airdata sensors, video cameras with cockpit displays, aircraft state and control-position measurements, inertial aircraft-position measurements, meteorological measurements, and an on-board personal computer for real-time processing and cockpit display of research data. To date, several of the preliminary system check flights and two meteorological-measurements deployments have been completed. Several wake encounter and wake-decay-measurements flights are planned for the fall of 1995.

Stuever, Robert A.↗
DOE OSTI2015

Upbend and M 1 scissors mode in neutron-rich nuclei - consequences for r-process $(n,\gamma )$ reaction rates

An enhanced probability for low-energy γ-emission ( upbend , Eγ < 3 MeV) at high excitation energies has been observed for several light and medium-mass nuclei close to the valley of stability. Also the M1 scissors mode seen in deformed nuclei increases the γ-decay probability for low-energy γ-rays (E γ ≈ 2–3 MeV). These phenomena, if present in neutron-rich nuclei, have the potential to increase radiative neutron-capture rates relevant for the r-process. Furthermore, the experimental and theoretical status of the upbend is discussed, and preliminary calculations of (n,γ) reaction rates for neutron-rich, mid-mass nuclei including the scissors mode are shown.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Estimation of electron temperature and density of the decay plasma in a laser-assisted discharge plasma extreme ultraviolet source by using a modified Stark broadening method

In order to investigate the plasma expansion behaviors and the electrical recovery process after the maximum implosion in our tin fueled laser-assisted discharge plasma (LDP) 13.5 nm EUV source, we developed and evaluated a cost-efficient spectroscopic method to determine the electron temperature T{sub e} and density n{sub e} simultaneously, by using Stark broadenings of two Sn II isolated lines (5s{sup 2}4f{sup 2}F{sup o}{sub 5/2} - 5s{sup 2}5d{sup 2}D{sub 3/2} 558.9 nm and 5s{sup 2}6d{sup 2}D{sub 5/2} - 5s{sup 2}6p{sup 2}P{sup o}{sub 3/2} 556.2 nm) spontaneously emitted from the plasma. The spatial-resolved evolutions of T{sub e} and n{sub e} of the expansion plasma over 50 to 900 ns after the maximum implosion were obtained using this modified Stark broadening method. According to the different n{sub e} decay characteristics along the Z-pinch axis, the expansion velocity of the electrons was estimated as {approx}1.2 x 10{sup 4} ms{sup -1} from the plasma shell between the electrodes towards the cathode and the anode. The decay time constant of n{sub e} was measured as 183 {+-} 24 ns. Based on the theories of plasma adiabatic expansion and electron-impact ionization, the minimum time-span that electrical recovery between the electrodes needs in order to guarantee the next succeeding regular EUV-emitting discharge was estimated to be 70.5 {mu}s. Therefore, the maximum repetition rate of our LDP EUV source is {approx}14 kHz, which enables the output to reach 125 W/(2{pi}sr).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

LOW-TEMPERATURE ION TRAP STUDIES OF N{sup +}({sup 3} P{sub ja} ) + H{sub 2}(j) {yields} NH{sup +} + H

Using a low-temperature 22-pole ion trap apparatus, detailed measurements for the title reaction have been performed between 10 K and 100 K in order to get some state specific information about this fundamental hydrogen abstraction process. The relative population of the two lowest H{sub 2} rotational states, j = 0 and 1, has been varied systematically. NH{sup +} formation is nearly thermo-neutral; however, to date, the energetics are not known with the accuracy required for low-temperature astrochemistry. Additional complications arise from the fact that, so far, there is no reliable theoretical or experimental information on how the reactivity of the N{sup +} ion depends on its fine-structure (FS) state {sup 3} P{sub ja} . Since in the present trapping experiment, thermalization of the initially hot FS population competes with hydrogen abstraction, the evaluation of the decay of N{sup +} ions over long storage times and at various He and H{sub 2} gas densities provides information on these processes. First assuming strict adiabatic behavior, a set of state specific rate coefficients is derived from the measured thermal rate coefficients. In addition, by recording the disappearance of the N{sup +} ions over several orders of magnitude, information on nonadiabatic transitions is extracted including FS-changing collisions.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Rigid-Rod Sulfonated Polyamide as an Aqueous-Processable Binder for Li-Ion Battery Electrodes

Polymer binders are important components of most battery electrodes, ensuring high performance and long-term durability. Increasing demand for lithium-ion batteries in the automotive, stationary power, and portable electronics industries calls for a greener binder to replace poly(vinylidene difluoride) (PVDF). We evaluate the performance of aqueous solution-processed electrodes prepared with a rigid-rod polymer binder, poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT). The polyamide backbone and double-helical configuration of PBDT give rise to its mechanical strength and rigidity, and its functional nature (H-bonding amides and sulfonates) can provide specific binding with electrode particles. LiFePO 4 electrodes prepared with 3 wt% PBDT show mechanical integrity and cycling stability, achieving over 1000 cycles at 4C rate with negligible capacity decay. These electrodes demonstrate comparable rate performance with their PVDF counterparts while eliminating fluorine from the electrode as well as the organic solvents needed for processing. Furthermore, this study reveals that PBDT holds great potential as a binder for advanced sustainable batteries.

25 ENERGY STORAGE↗