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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Optimizing the LSST Observing Strategy for Dark Energy Science: DESC Recommendations for the Deep Drilling Fields and other Special Programs

We review the measurements of dark energy enabled by observations of the Deep Drilling Fields and the optimization of survey design for cosmological measurements. This white paper is the result of efforts by the LSST DESC Observing Strategy Task Force (OSTF), which represents the entire collaboration, and aims to make recommendations on observing strategy for the DDFs that will benefit all cosmological analyses with LSST. It is accompanied by the DESC-WFD white paper (Lochner et al.). We argue for altering the nominal deep drilling plan to have $>6$ month seasons, interweaving $gri$ and $zy$ observations every 3 days with 2, 4, 8, 25, 4 visits in $grizy$, respectively. These recommendations are guided by metrics optimizing constraints on dark energy and mitigation of systematic uncertainties, including specific requirements on total number of visits after Y1 and Y10 for photometric redshifts (photo-$z$) and weak lensing systematics. We specify the precise locations for the previously-chosen LSST deep fields (ELAIS-S1, XMM-LSS, CDF-S, and COSMOS) and recommend Akari Deep Field South as the planned fifth deep field in order to synergize with Euclid and WFIRST. Our recommended DDF strategy uses $6.2\%$ of the LSST survey time. We briefly discuss synergy with white papers from other collaborations, as well as additional mini-surveys and Target-of-Opportunity programs that lead to better measurements of dark energy.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Probabilistic Risk Assessment of a Light Water Reactor Coupled with a High Temperature Electrolysis Hydrogen Production Plant

Two generic probabilistic risk assessments (PRA) for the addition of a heat extraction system (HES) addition to a light water reactor (LWR) are performed, one for a pressurized water reactor (PWR) and one for a boiling water reactor (BWR). The results investigate the applicability of the potential licensing approaches which do not require a full U.S. Nuclear Regulatory Commission (NRC) licensing review. The PRAs are generic, and some assumptions are made. Many conservative assumptions from a the preliminary PWR PRA report were eliminated using design data for both the HES and the high temperature electrolysis facility (HTEF). The results of the PRA indicate that the 10 CFR 50.59 licensing approach is justified due to the minimal increase in initiating event frequencies for all DBAs, none exceeding 5.6%. The PRA results for CDF and LERF support the use of RG 1.174 as further risk information that supports a change without a full LAR. Further insights provided through hazard analysis and sensitivity studies confirm with high confidence that the safety case for licensing an HES addition and a HTEF sited at 1.0 km from the NPP is strong and that the placement of a HTEF at 0.5 km is a viable case. Site specific information can alter these conclusions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Towards a combination of LHC and TeVatron W-boson mass measurements

In this note methodological and modelling considerations towards a combination of the ATLAS, CDF and D0 measurements of the W -boson mass are discussed. As they were performed at different moments in time, each measurement employed different assumptions for the modelling of W -boson production and decay, as well as different fits of the parton distribution functions of the proton (PDFs). Methods are presented to accurately evaluate the effect of PDFs and other modelling variations on existing measurements, allowing to extrapolate them to any PDF set and to evaluate the corresponding uncertainties. Based on this approach, the measurements can be corrected to a common modelling reference and to the same PDFs, and subsequently combined accounting for PDF correlations in a quantitative way.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Development and Integration of a Stochastic Clad Damage Propagation Model into PRONGHORN-SC Subchannel Analysis Code

The failure of fuel pins in nuclear reactors is intrinsically stochastic. Typically, a combination of variation in manufacturing that affects the material characteristics and the fuel assembly dimensions, variation in operating conditions, such as local power, coolant flow rate, and irradiation induced changes in material properties lead to a large uncertainty in failure margin of the fuel pins. Failure, therefore, may occur in exceptional pins with adverse combinations of these variations. Upon a metal fuel pin (U-Pu-Zr/HT9) failure, depressurization of the fuel pin takes place by release of fission gas, liquid sodium bond, and potentially solid fuel particles or molten/eutectic fuel droplets through the hole in cladding. The effect of a fission gas jet on neighbor fuel pins and possible propagation of a clad damage during normal operation was studied experimentally in 1970s and it was found that the post-failure fission gas jet insulates the jet impingement area of the target fuel pin surface and could increase the target pin’s surface temperature by as much as 100 – 200 K during the failed pin depressurization. It was concluded that the effect should not lead to fuel pin failure propagation during normal operation. In accident scenarios of sodium and lead fast reactors such as Unprotected Loss-Of-Flow (ULOF) or Unprotected Transient Over Power (UTOP), the fuel pins can be subjected to higher clad temperatures and fuel pin pressures or fuel clad mechanical/chemical interaction where thermal creep margin becomes significantly lower compared to the normal operation conditions. Therefore, possible stochastic failure and the post-failure fission gas/fuel jet impingement could be critical in order to predict fuel pin failure propagation. Pin depressurization due to fission gas release may degrade the heat transfer by formation of a gas blanket on a neighboring pin surface, which is a local phenomenon, and by causing coolant flow deceleration and starvation, which could affect a surrounding region as well. Furthermore, the potential presence of solid fuel particles or molten fuel at the time of clad failure could boost post-failure jet induced degradation even further. The present study models the U-Pu-Zr/HT9 metal fuel pin failure and stochastic clad damage propagation by biased sampling based on a Cumulative Damage Fraction (CDF) type clad failure criterion and the normal distribution of fuel failure probability density as a function of logarithm of Cumulative Damage Fraction. In addition, the effect of post-failure fission gas jet on heat transfer degradation is modeled for the target pins. This model is called stochastic Clad Damage Propagation (CDAP). The CDAP model is now fully integrated into developmental version of PRONGHORN-SC subchannel analysis code, allowing for modeling local failures and its propagation potential. Section 2 describes the components of the CDAP models. Section 3 describes the model implementation to PRONGHORN-SC and input specifications. Section 4 describes the CDAP model validation coupled to PRONGHORN-SC.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2010

The Higgs boson in the Standard Model theoretical constraints and a direct search in the wh channel at the Tevatron

We have presented results in two different yet strongly linked aspects of Higgs boson physics. We have learned about the importance of the Higgs boson for the fate of the Standard Model, being either only a theory limited to explaining phenomena at the electroweak scale or, if the Higgs boson lies within a mass range of 130 < m H < 160 GeV the SM would remain a self consistent theory up to highest energy scales O(m Pl ). This could have direct implications on theories of cosmological inflation using the Higgs boson as the particle giving rise to inflation in the very early Universe, if it couples non-minimally to gravity, an effect that would only become significant at very high energies. After understanding the immense meaning of proving whether the Higgs boson exists and if so, at which mass, we have presented a direct search for a Higgs boson in associated production with a W boson in a mass range 100 < m H < 150 GeV. A light Higgs boson is favored regarding constraints from electroweak precision measurements. As a single analysis is not yet sensitive for an observation of the Higgs boson using 5.3 fb -1 of Tevatron data, we set limits on the production cross section times branching ratio. At the Tevatron, however, we are able to combine the sensitivity of our analyses not only across channels or analyses at a single experiment but also across both experiments, namely CDF and D0. This yields to the so-called Tevatron Higgs combination which, in total, combines 129 analyses from both experiments with luminosities of up to 6.7 fb -1 . The results of a previous Tevatron combination led to the first exclusion of possible Higgs boson masses since the LEP exclusion in 2001. The latest Tevatron combination from July 2010 can be seen in Fig. 111 and limits compared to the Standard Model expectation are listed in Table 23. It excludes a SM Higgs boson in the regions of 100 < m H < 109 GeV as well as 158 < m H < 175 GeV based on the observed final limits at 95% C.L. In the most interesting low mass region between 115 and 135 GeV, even the full Tevatron combination is not yet sensitive enough to exclude a Higgs boson, or to even prove its existence with a meaningful significance. Fig. 112 shows a projection plot for sensitivity to the SM Higgs boson at the Tevatron as a measure of increasing luminosity. The 10 fb -1 projection is a rather conservative outlook for the coming year of data taking as the Tevatron runs smoothly and the run till the end of 2011 is assured. By now, already 9 fb -1 have been recorded by the two experiments. As the extrapolation plot shows, this amount of luminosity will allow to exclude the Higgs boson over a wide mass range at a 95% C.L. With the LHC at CERN now running and successfully collecting first data, it is worth looking at projections of Higgs boson sensitivity at the current center of mass energy of 7 TeV of the LHC accelerator. Fig. 113 shows a projection of a possible SM Higgs boson exclusion using 1 fb -1 of LHC data collected by the ATLAS experiment. An exclusion is expected between 135 and 188 GeV at 95% C.L., combining the three decay channels H → WW, H → ZZ and H → γγ. A combination between LHC experiments would possibly yield an even broader range of excluded Higgs boson mass points. Therefore, whether at the Tevatron or the LHC, exciting times in the exclusion or possible discovery of the SM Higgs boson lie ahead.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Higgs Searches at the Tevatron

We present combined CDF and D0 searches for the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) Higgs boson using up to 6.7 fb$^{-1}$ of integrated luminosity from 1.96 TeV proton-antiproton collisions at the Tevatron. Specialized searches for Higgs bosons produced via gluon fusion, associated boson production, and vector boson fusion, decaying to $b\bar{b}$, $W^{+}W^{-}$, $\tau^{+}\tau^{-}$, and $\gamma\gamma$ are combined to produce 95\% CL upper limits on SM Higgs production as a function of mass. Current Tevatron limits are shown, including a new exclusion for SM Higgs masses between 158 and 175 GeV$/c^2$. We also present prospects for future sensitivity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Combination of the top-quark mass measurements from the Tevatron and from the LHC colliders

I present here the results for the combination of the top-quark mass (mt) measurements at the Tevatron and at the LHC. These combinations are based on measurements using up to 5.8 fb-1 from CDF and D0 yielding mt=173.18 +- 0.56(stat) +- 0.75(syst) GeV, and up to 4.7 fb-1 from ATLAS and CMS leading to mt=173.3 +-0.5(stat) +-1.3(syst) GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Searches for new resonances from BSM physics at Tevatron and LHC

Several months after the end of the first run of the LHC, the searches for physics beyond the Standard Model (BSM) are now well developed. A powerful tool for such a quest is the search for new resonances. The latest and most interesting results from ATLAS, CDF, CMS and D0 in this field are reviewed, focusing on non supersymmetric resonance searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Single top quark production cross section at the Tevatron

The latest results on the measurements of electroweak top-quark production at the Tevatron are presented with the full RunII dataset. The CDF and DO collaborations have performed measurements of the s , t , and s + t channels in both &ell;+jets and Ɇ T +jets final states. Evidence for the production of the s channel is presented for the first time.

Garcia-Bellido, Aran↗
DOE OSTI2016

Review of top quark production at LHC and Tevatron

A summary of recent results on top quark production at LHC and Tevatron are presented in this paper. The measurements of top quark production were performed in various energies ($\sqrt s$ = 1.96, 7, 8, 13 TeV) and initial states ($p \bar{p}$ and $p p$) by the ATLAS, CDF, CMS, DØ and LHCb ex- periments. The measured top quark pair production cross-section is in good agreement with the standard model predictions in each energy region. Differential cross-sections were also measured and compared with several theoretical predictions. Most of the higher order QCD models reproduce the experimental data well, while a slight discrepancy in a certain phase space such as higher top quark $p_{T}$ region is observed. Electroweak single top quark production was also measured and the results are consistent with theoretical predictions at the various energies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Top Quark Properties

An overview of recent top quark measurements in proton-proton collisions at $\sqrt s$ = 7, 8 TeV in data collected with the CMS and ATLAS experiments at the LHC, using a data sample collected during the years 2011 and 2012 is presented. The results include measurements of the $t \bar{t}$ spin correlation, the top pair charge asymmetry, and the cross section of $t \bar{t}$ events produced in association with a W or a Z boson. The mass of the top quark is measured using different methods. Some results on the same topics are also presented in data collected by the CDF and D0 collaborations at the Tevatron collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Top-quark properties at hadron colliders

Recent results on top -quark properties and interactions are presented, obtained using data collected with the LHC ATLAS and CMS experiments during the years 2011 and 2012 at 7 and 8 TeV pp center-of-mass energies, and with the Tevatron's CDF and D0 experiments at 1.96 TeV $p\bar{p}$p center-of-mass energy . The mass of the top-quark is extracted using several methods, including indirect constraints from the measured cross section. Further results include measurements of top -quark properties, such as the top pair charge asymmetry, spin correlation and polarization, as well as the search for anomalous couplings and charge-parity violation in top-quark pair production. No deviations were found with respect to the predictions of the Standard Model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurements of the top quark mass from the LHC and the Tevatron

The mass of the top quark is a fundamental parameter of the standard model and has to be determined experimentally. In these proceedings, I review recent measurements of the top quark mass in $pp$ collisions at $\sqrt s=7,~8,$ and 13 TeV recorded by the ATLAS and CMS detectors at the LHC, and in $p\bar p$ collisions at $\sqrt s=1.96$ TeV recorded by the CDF and D0 experiments at the Tevatron. The measurements are performed in final states containing two, one, and no charged leptons. A relative precision of down to 0.3% is attained. In addition, recent measurements aiming to determine the top quark mass in the well-defined pole scheme using both inclusive $t\bar t$ and $t\bar t+1~{\rm jet}$ production are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Top Quark Physics at the Tevatron

A selection of the most recent CDF and D0 results in the top quark sector is presented. The most recent top quark mass measurements, including the pole mass determinationobtained from cross section measurements, are discussed. The Tevatron combined $t{\bar{t}}$ charge asymmetry results areshown. The recent top quark polarization measurements are reviewed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Combined upper limit on standard model higgs boson production at D0 in $p \bar{p}$ collisions at $\sqrt{s} = 1.96-TeV

The latest searches for the Standard Model Higgs boson at a centre-of-mass energy of {radical}s = 1.96 TeV with the D0 and the CDF detectors at the Fermilab Tevatron collider are presented. For the first time since the LEP experiments the sensitivity for a Standard Model Higgs boson has been reached at a Higgs boson mass of 170 GeV/c{sup 2}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Alternative methods for top-quark mass determination at the Tevatron and LHC

I am summarizing here the determination of the top-quark mass from the CDF and D0 Collaborations at the Tevatron and the ATLAS and CMS Collaborations at the LHC using non-conventional methods. I am concentrating on the extraction of the top-quark mass from the top-antitop cross-section, on the mass measurement using the so-called endpoint method and on the top-quark mass determination from the $b$-lifetime.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Leptons: $\mathbf{e}$, $\boldsymbol{\mu}$, $\boldsymbol{\tau}$ + systematic uncertainties

An overview of the charged lepton performance in the ATLAS and CMS experiments at the LHC and in the CDF and D0 experiments at the Tevatron is given, in the specific context of physics analyses requiring the selection of leptons from top-quark decays. The trigger and reconstruction algorithms are presented, as well as the identification and isolation criteria, pointing out the specificities of top-quark analysis selections. The impact of the lepton-related experimental systematic uncertainties are discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗