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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Measurements of inclusive and differential fiducial cross-sections of $t\bar{t}\gamma $ production in leptonic final states at $\sqrt{s}=13~\text {TeV}$ TeV in ATLAS

Inclusive and differential cross-sections for the production of a top-quark pair in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 36.1 fb –1 , collected by the ATLAS detector at the LHC in 2015 and 2016 at a centre-of-mass energy of 13 TeV. The measurements are performed in single-lepton and dilepton final states in a fiducial volume. Events with exactly one photon, one or two leptons, a channel-dependent minimum number of jets, and at least one b-jet are selected. Neural network algorithms are used to separate the signal from the backgrounds. The fiducial cross-sections are measured to be 521 ± 9(stat.) ± 41(sys.) fb and 69 ± 3(stat.) ± 4(sys.) fb for the single-lepton and dilepton channels, respectively. The differential cross-sections are measured as a function of photon transverse momentum, photon absolute pseudorapidity, and angular distance between the photon and its closest lepton in both channels, as well as azimuthal opening angle and absolute pseudorapidity difference between the two leptons in the dilepton channel. All measurements are in agreement with the theoretical predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Recherche du boson de Higgs dans l'état final dimuonique et étude de l'asymétrie de production de la paire top antitop avec l'expérience DO auprès du Tevatron; Higgs boson search in the dimuonique final state and study of the top pair antitop production asymmetry with the DO experiment at the Tevatron.

Two high energy particle physics analyses are presented in this PhD report using events with two leptons oppositely charged and with missing transverse energy. These events are selected using 9.7 fb-1 of total pp collisions data collected with the DØ detector at the TeVatron at √s=1.96 TeV.The first analysis is the research of the Higgs boson decaying in the H→WW→μνμν channel. No significant excess above the background prediction is observed.Upper limits on Higgs boson production cross-section are computed in the standard model framework but also in the 4th generation of fermions and in the fermiophobic coupling to Higgs boson hypotheses. In order to validate the research methodology, the W boson pair production cross-section is measured.The second analysis is the measurement of the forward-backward asymmetry of the tt pair production. This is the first measurement in the dileptonic channel at DØ experiment. In this context, a new tt pair kinematic reconstruction is used (matrix element method) to give a raw measurement of the forward-backward asymmetry. Thanks to a dedicated calibration method, we give a final measurement of AFB=18.0 ± 6.0 (stat) ± 3.3 (syst).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

I. Final Report for DOE SBIR Phase I Project DE-SC0013795 Final Report for DOE SBIR Phase I Project DE-SC0013795 Microtron-based Compact, Portable Gamma-Ray Source

Microtron-based Compact, Portable Gamma-Ray Source. The objective of Phase I of this project was to produce a conceptual design of a prototype compact microtron electron accelerator, which could be designed, built, and demonstrated in Phase II of the project. The conceptual design study included an analysis of the parameters of the microtron and its components, and the expected performance of the prototype microtron as a source of x-rays and/or RF neutrons in the MeV energy range. The major components of the microtron are the magnet, the accelerating system, the power system, the vacuum system, the control system, the beam extraction system and the targets to produce x-rays (and/or neutrons). Our objectives for the design of the prototype were for it to be compact, cost-effective, capable of producing high intensity x-ray (an/or neutron) fluxes. In addition, the prototype was to be easily assembled and disassembled so that components could be easily replaced. The main parameters for the prototype are the following: the range of electron kinetic energies, the output power, the RF frequency band (X-band, C-band, or S-Band), the type of injection (Type I or Type II), the magnet type, i.e. permanent magnet, electromagnet, or a hybrid combination of permanent and electromagnet. The results of the Phase I study and analysis for a prototype microtron are the following: The electron energy range can be varied from below 6 MeV to 9 MeV, the optimal frequency range is S-Band (2-4 GHz) RF frequency, Type II injection (described below), and the magnet type is the hybrid version. The prototype version will be capable of producing gamma ray doses of ~1800 R/min-m and neutron fluxes of up to ~6 x 10 10 n/s with appropriate targets. The results of the Phase I study and analysis are provided below. The proposed Phase II plan was to demonstrate the prototype at low beam power. In the subsequent Phase III, high power tests would be performed, and the design of commercial versions of microtrons with various energies, sizes and types would be produced and marketed, including a more compact and more portable 6 MeV battery-powered model that more closely meets the requirements in the original FOA topic description. In the course of the Phase I study, we also identified another microtron version, one that was larger (not compact) and more powerful than that of the Phase II prototype, which could serve as an intense source of photo- neutrons, up to 4 x 10 12 n/s for use in nuclear medicine, short-lived isotope production, or other applications. In addition, it could produce gamma dose rates up to 130 kR/min-m with a heavy metal bremsstrahlung target. The results and specifications of this were submitted to IPAC16 (Reference [12]) the paper is included in Addendum B. Because this version was beyond the scope of the Phase I project, there is no additional description in the Final Report.

43 PARTICLE ACCELERATORS↗
NASA NTRS2011

C-Band Airport Surface Communications System Standards Development. Phase II Final Report. Volume 2: Test Bed Performance Evaluation and Final AeroMACS Recommendations

This report is provided as part of ITT s NASA Glenn Research Center Aerospace Communication Systems Technical Support (ACSTS) contract NNC05CA85C, Task 7: New ATM Requirements-Future Communications, C-Band and L-Band Communications Standard Development and was based on direction provided by FAA project-level agreements for New ATM Requirements-Future Communications. Task 7 included two subtasks. Subtask 7-1 addressed C-band (5091- to 5150-MHz) airport surface data communications standards development, systems engineering, test bed and prototype development, and tests and demonstrations to establish operational capability for the Aeronautical Mobile Airport Communications System (AeroMACS). Subtask 7-2 focused on systems engineering and development support of the L-band digital aeronautical communications system (L-DACS). Subtask 7-1 consisted of two phases. Phase I included development of AeroMACS concepts of use, requirements, architecture, and initial high-level safety risk assessment. Phase II builds on Phase I results and is presented in two volumes. Volume I is devoted to concepts of use, system requirements, and architecture, including AeroMACS design considerations. Volume II (this document) describes an AeroMACS prototype evaluation and presents final AeroMACS recommendations. This report also describes airport categorization and channelization methodologies. The purposes of the airport categorization task were (1) to facilitate initial AeroMACS architecture designs and enable budgetary projections by creating a set of airport categories based on common airport characteristics and design objectives, and (2) to offer high-level guidance to potential AeroMACS technology and policy development sponsors and service providers. A channelization plan methodology was developed because a common global methodology is needed to assure seamless interoperability among diverse AeroMACS services potentially supplied by multiple service providers.

Hall, Edward↗
DOE OSTI2019

Search for heavy Majorana or Dirac neutrinos and right-handed W gauge bosons in final states with two charged leptons and two jets at $\sqrt{s}=13 $ TeV with the ATLAS detector

A search for heavy right-handed Majorana or Dirac neutrinos NR and heavy right-handed gauge bosons WR is performed in events with a pair of energetic electrons or muons, with the same or opposite electric charge, and two energetic jets. The events are selected from pp collision data with an integrated luminosity of 36.1 fb -1 collected by the ATLAS detector at s√=13 TeV. No significant deviations from the Standard Model are observed. The results are interpreted within the theoretical framework of a left-right symmetric model and lower limits are set on masses in the heavy right-handed W boson and neutrino mass plane. The excluded region extends to m$_{R_R}$=4.7 TeV for both Majorana and Dirac N R neutrinos.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Differential top-antitop cross-section measurements as a function of observables constructed from final-state particles using pp collisions at $\sqrt{s}=7 $ TeV in the ATLAS detector

Various differential cross-sections are measured in top-quark pair (tt) events produced in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the LHC with the ATLAS detect or. These differential cross-sections are presented in a data set corresponding to an integrated luminosity of 4.6 fb -1 . The differential cross-sections are presented in terms of kinematic variables, such as momentum, rapidity and invariant mass, of a top-quark proxy referred to as the pseudo-top-quark as well as the pseudo-top-quark pair system. The dependence of the measurement on theoretical models is minimal. The measurements are performed on tt events in the lepton+jets channel, requiring exactly one charged lepton and at least four jets with at least two of them tagged as originating from a b-quark. The hadronic and leptonic pseudo-top-quarks are defined via the leptonic or hadronic decay mode of the W boson produced by the top-quark decay in events with a single charged lepton. Differential cross-section measurements of the pseudo-top-quark variables are compared with several Monte Carlo models that implement next-to-leading order or leading-order multi-leg matrix-element calculations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Erratum to: Search for supersymmetry in final states with two same-sign or three leptons and jets using 36 fb -1 of $ \sqrt{s} $ = 13 TeV pp collision data with the ATLAS detector

One correction is made to the figure 4e of the paper. The reported cross-sections, both the experimental upper limits and the theoretical prediction, corresponded only to a fiducial region of the phase space with at least two prompt same-sign electrons or muons before detector simulation (p T > 10 GeV, |η| < 2.8). The updated figure 4e instead presents the results without this requirement, i.e. in the full phase space as it should, given the y-axis label of the plot. The reported sensitivity of the analysis, i.e. the ability to exclude top squark masses below 700 GeV in this scenario, is however unchanged since the same requirements were applied to the analysis and to the theory predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of jet activity in top quark events using the eμ final state with two b-tagged jets in pp collisions at $\sqrt{s}=8 $ TeV with the ATLAS detector

Measurements of the jet activity in tt¯ events produced in proton-proton collisions at √s=8 TeV are presented, using 20.3 fb –1 of data collected by the ATLAS experiment at the Large Hadron Collider. The events were selected in the dilepton eμ decay channel with two identified b-jets. The numbers of additional jets for various jet transverse momentum (p T ) thresholds, and the normalised differential cross-sections as a function of p T for the five highest-p T additional jets, were measured in the jet pseudo-rapidity range |η| < 4.5. The gap fraction, the fraction of events which do not contain an additional jet in a central rapidity region, was measured for several rapidity intervals as a function of the minimum p T of a single jet or the scalar sum of p T of all additional jets. These fractions were also measured in different intervals of the invariant mass of the eμbb¯ system. All measurements were corrected for detector effects, and found to be mostly well-described by predictions from next-to-leading-order and leading-order tt¯ event generators with appropriate parameter choices. Lastly, the results can be used to further optimise the parameters used in such generators.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Search for a heavy Higgs boson decaying into a Z boson and another heavy Higgs boson in the ℓℓbb final state in pp collisions at s = 13 TeV with the ATLAS detector

A search for a heavy neutral Higgs boson, A, decaying into a Z boson and another heavy Higgs boson, H, is performed using a data sample corresponding to an integrated luminosity of 36.1 fb -1 from proton–proton collisions at $ \sqrt{s}=13 $ TeV recorded in 2015 and 2016 by the ATLAS detector at the Large Hadron Collider. The search considers the Z boson decaying to electrons or muons and the H boson into a pair of b-quarks. No evidence for the production of an A boson is found. Considering each production process separately, the 95% confidence-level upper limits on the pp→A→ZH production cross-section times the branching ratio H→bb are in the range of 14–830 fb for the gluon–gluon fusion process and 26–570 fb for the b-associated process for the mass ranges 130–700 GeV of the H boson and 230–800 GeV of the A boson. The results are interpreted in the context of two-Higgs-doublet models.

Aaboud, M.↗