3,316 Matching Results

Results open in a new window/tab.

Parallel Ion Energy Spread Due to Interaction With an Electron Bunch in the RHIC Electron Beam Cooling Solenoid (open access)

Parallel Ion Energy Spread Due to Interaction With an Electron Bunch in the RHIC Electron Beam Cooling Solenoid

N/A
Date: June 1, 2003
Creator: A., Hershcovitch
Object Type: Report
System: The UNT Digital Library
Feasibility Study of a 1.5-GeV Proton FFAG in the AGS Tunnel (open access)

Feasibility Study of a 1.5-GeV Proton FFAG in the AGS Tunnel

N/A
Date: June 1, 2004
Creator: A., Ruggiero
Object Type: Report
System: The UNT Digital Library
Evolution of Stress in ScD{sub 2}/Cr Thin Films Fabricated by Evaporation and High Temperature Reaction (open access)

Evolution of Stress in ScD{sub 2}/Cr Thin Films Fabricated by Evaporation and High Temperature Reaction

The stress of scandium dideuteride, ScD{sub 2}, thin films is investigated during each stage of vacuum processing including metal deposition via evaporation, reaction and cooldown. ScD{sub 2} films with thin Cr underlayers are fabricated on three different substrate materials: molybdenum-alumina cermet, single crystal sapphire and quartz. In all experiments, the evaporated Cr and Sc metal is relatively stress-free. However, reaction of scandium metal with deuterium at elevated temperature to form a stoichiometric dideuteride phase leads to a large compressive in-plane film stress. Compression during hydriding results from an increased atomic density compared with the as-deposited metal film. After reaction with deuterium, samples are cooled to ambient temperature, and a tensile stress develops due to mismatched coefficients of thermal expansion (CTE) of the substrate-film couple. The residual film stress and the propensity for films to crack during cooldown depends principally on the substrate material when using identical process parameters. Films deposited onto quartz substrates show evidence of stress relief during cooldown due to a large CTE misfit; this is correlated with crack nucleation and propagation within films. All ScD{sub 2} layers remain in a state of tension when cooled to 30 C. An in-situ, laser-based, wafer curvature sensor is designed and …
Date: June 1, 2001
Creator: ADAMS,DAVID P.; BROWN,LAURENCE E.; GOEKE,RONALD S.; ROMERO,JUAN A. & SILVA,ANDREW D.
Object Type: Report
System: The UNT Digital Library
EFFECTS OF IN-PLANE STRAIN ON ORBITAL ORDERING AND MAGNETISM IN LaMnO3 THIN FILM (open access)

EFFECTS OF IN-PLANE STRAIN ON ORBITAL ORDERING AND MAGNETISM IN LaMnO3 THIN FILM

None
Date: June 1, 2001
Creator: AHN, K. & MILLIS, A.
Object Type: Article
System: The UNT Digital Library
EFFECT OF TEMPERATURE PROFILE ON REACTION VIOLENCE IN HEATED AND SELF-IGNITED PBX-9501 (open access)

EFFECT OF TEMPERATURE PROFILE ON REACTION VIOLENCE IN HEATED AND SELF-IGNITED PBX-9501

None
Date: June 1, 2001
Creator: ASAY, B.; DICKSON, P. & AL, ET
Object Type: Article
System: The UNT Digital Library
Power Technologies Data Book 2003 Edition (open access)

Power Technologies Data Book 2003 Edition

The 2003 edition of this report, prepared by NREL's Energy Analysis Office, includes up-to-date information on power technologies, including complete technology profiles. The data book also contains charts on electricity restructuring, power technology forecasts and comparisons, electricity supply, electricity capability, electricity generation, electricity demand, prices, economic indicators, environmental indicators, conversion factors, and selected congressional questions and answers.
Date: June 1, 2004
Creator: Aabakken, J.
Object Type: Report
System: The UNT Digital Library
Measurement of b-jet Shapes in Inclusive Jet Production in p anti-p Collisions at s**(1/2) = 1.96-TeV (open access)

Measurement of b-jet Shapes in Inclusive Jet Production in p anti-p Collisions at s**(1/2) = 1.96-TeV

We present a measurement of the shapes of b-jets using 300 pb{sup -1} of data obtained with the upgraded Collider Detector at Fermilab (CDF II) in p{bar p} collisions at center of mass energy {radical}s = 1.96 TeV. This measurement covers a wide transverse momentum range, from 52 to 300 GeV/c. Samples of heavy-flavor enhanced jets together with inclusive jets are used to extract the average shapes of b-jets. The b-jets are expected to be broader than inclusive jets. Moreover, b-jets containing a single b-quark are expected to be narrower than those containing a b{bar b} pair from gluon splitting. The measured b-jet shapes are found to be significantly broader than expected from the pythia and HERWIG Monte Carlo simulations. This effect may arise from an underestimation of the fraction of b-jets originating from gluon splitting in these simulations.
Date: June 1, 2008
Creator: Aaltonen, T.
Object Type: Article
System: The UNT Digital Library
Measurement of the p anti-p ---> t anti-t production cross- section and the top quark mass at s**(1/2) = 1.96-TeV in the all-hadronic decay mode (open access)

Measurement of the p anti-p ---> t anti-t production cross- section and the top quark mass at s**(1/2) = 1.96-TeV in the all-hadronic decay mode

We report the measurements of the t{bar t} production cross section and of the top quark mass using 1.02 fb{sup -1} of p{bar p} data collected with the CDF II detector at the Fermilab Tevatron. We select events with six or more jets on which a number of kinematical requirements are imposed by means of a neural network algorithm. At least one of these jets must be identified as initiated by a b-quark candidate by the reconstruction of a secondary vertex. The cross section is measured to be {sigma}{sub t{bar t}} = 8.3 {+-} 1.0(stat. ){sup +2.0}{sub -1.5}(syst.) {+-} 0.5(lumi.) pb, which is consistent with the standard model prediction. The top quark mass of 174.0 {+-} 2.2(stat.){+-}4.8(syst.) GeV/c{sup 2} is derived from a likelihood fit incorporating reconstructed mass distributions representative of signal and background.
Date: June 1, 2007
Creator: Aaltonen, T.; Abulencia, A.; Phys., /Helsinki Inst. of; Adelman, J.; /Illinois U., Urbana; Affolder, Anthony Allen et al.
Object Type: Article
System: The UNT Digital Library
Forward-Backward Asymmetry in Top Quark Production in ppbar Collisions at sqrt{s}=1.96 TeV (open access)

Forward-Backward Asymmetry in Top Quark Production in ppbar Collisions at sqrt{s}=1.96 TeV

Reconstructable final state kinematics and charge assignment in the reaction p{bar p} {yields} t{bar t} allows tests of discrete strong interaction symmetries at high energy. We define frame dependent forward-backward asymmetries for the outgoing top quark in both the p{bar p} and t{bar t} rest frames, correct for experimental distortions, and derive values at the parton-level. Using 1.9 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV recorded with the CDF II detector at the Fermilab Tevatron, we measure forward-backward top quark production asymmetries in the p{bar p} and t{bar t} rest frames of A{sub FB}{sup p{bar p}} = 0.17 {+-} 0.08 and A{sub FB}{sup t{bar t}} = 0.24 {+-} 0.14.
Date: June 1, 2008
Creator: Aaltonen, T.; Adelman, J.; Akimoto, T.; Albrow, M. G.; Alvarez Gonzalez, B.; Amerio, S. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the Top Quark Mass Using the Invariant Mass of Lepton Pairs in Soft Muon b-tagged Events (open access)

Measurement of the Top Quark Mass Using the Invariant Mass of Lepton Pairs in Soft Muon b-tagged Events

We present the first measurement of the mass of the top quark in a sample of t{bar t} {yields} {ell}{bar {nu}}b{bar b}q{bar q} events (where {ell} = e, {mu}) selected by identifying jets containing a muon candidate from the semileptonic decay of heavy-flavor hadrons (soft muon b-tagging). The p{bar p} collision data used corresponds to an integrated luminosity of 2 fb{sup -1} and was collected by the CDF II detector at the Fermilab Tevatron. The measurement is based on a novel technique exploiting the invariant mass of a subset of the decay particles, specifically the lepton from the W boson of the t {yields} Wb decay, and the muon from a semileptonic b decay. We fit template histograms, derived from simulation of t{bar t} events and a modeling of the background, to the mass distribution observed in the data and measure a top quark mass of 180.5 {+-} 12.0(stat.) {+-} 3.6(syst.) GeV/c{sup 2}, consistent with the current world average.
Date: June 1, 2009
Creator: Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E. et al.
Object Type: Article
System: The UNT Digital Library
Search for Higgs bosons predicted in two-Higgs-doublet models via decays to tau lepton pairs in 1.96-TeV p anti-p collisions (open access)

Search for Higgs bosons predicted in two-Higgs-doublet models via decays to tau lepton pairs in 1.96-TeV p anti-p collisions

We present the results of a search for Higgs bosons predicted in two-Higgs-doublet models, in the case where the Higgs bosons decay to tau lepton pairs, using 1.8 fb{sup -1} of integrated luminosity of p{bar p} collisions recorded by the CDF II experiment at the Fermilab Tevatron. Studying the mass distribution in events where one or both tau leptons decay leptonically, no evidence for a Higgs boson signal is observed. The result is used to infer exclusion limits in the two-dimensional space of tan {beta} versus m{sub A} (the ratio of the vaccum expectation values of the two Higgs doublets and the mass of the pseudoscalar boson, respectively).
Date: June 1, 2009
Creator: Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E. et al.
Object Type: Article
System: The UNT Digital Library
Search for New Particles Leading to Z+jets Final States in p anti-p Collisions at s**(1/2) = 1.96-TeV (open access)

Search for New Particles Leading to Z+jets Final States in p anti-p Collisions at s**(1/2) = 1.96-TeV

We present the results of a search for new particles that lead to a Z boson plus jets in p{bar p} collisions at {radical}s = 1.96 TeV using the Collider Detector at Fermilab (CDF II). A data sample with a luminosity of 1.06 fb{sup -1} collected using Z boson decays to ee and {mu}{mu} is used. We describe a completely data-based method to predict the dominant background from standard-model Z+jet events. This method can be similarly applied to other analyses requiring background predictions in multi-jet environments, as shown when validating the method by predicting the background from W+jets in t{bar t} production. No significant excess above the background prediction is observed, and a limit is set using a fourth generation quark model to quantify the acceptance. Assuming BR(b{prime} {yields} bZ) = 100% and using a leading-order calculation of the b{prime} cross section, b{prime} quark masses below 268 GeV/c2 are excluded at 95% confidence level.
Date: June 1, 2007
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Abulencia, A.; /Illinois U., Urbana; Adelman, J.; U., /Chicago et al.
Object Type: Article
System: The UNT Digital Library
Search for a Higgs Boson in W H --> l nu b anti-b in p anti-p Collisions at s**(1/2) = 1.96 TeV (open access)

Search for a Higgs Boson in W H --> l nu b anti-b in p anti-p Collisions at s**(1/2) = 1.96 TeV

We present a search for a standard model Higgs boson produced in association with a W boson using 2.7 fb{sup -1} of integrated luminosity of p{bar p} collision data taken at {radical}s = 1.96 TeV. Limits on the Higgs boson production rate are obtained for masses between 100 GeV/c{sup 2} and 150 GeV/c{sup 2}. Through the use of multivariate techniques, the analysis achieves an observed (expected) 95% confidence level upper limit of 5.6 (4.8) times the theoretically expected production cross section for a standard model Higgs boson with a mass of 115 GeV/c{sup 2}.
Date: June 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Object Type: Article
System: The UNT Digital Library
Searching the Inclusive Lepton + Photon + Missing E(T) + b-quark Signature for Radiative Top Quark Decay and Non-Standard-Model Processes (open access)

Searching the Inclusive Lepton + Photon + Missing E(T) + b-quark Signature for Radiative Top Quark Decay and Non-Standard-Model Processes

In a search for new phenomena in a signature suppressed in the standard model of elementary particles (SM), we compare the inclusive production of events containing a lepton ({ell}), a photon ({gamma}), significant transverse momentum imbalance (E{sub T}), and a jet identified as containing a b-quark, to SM predictions. The search uses data produced in proton-antiproton collisions at {radical}s = 1.96 TeV corresponding to 1.9 fb{sup -1} of integrated luminosity taken with the CDF detector at the Fermilab Tevatron. We find 28 {ell}{gamma}bE{sub T} events versus an expectation of 31.0{sub -3.5}{sup +4.1} events. If we further require events to contain at least three jets and large total transverse energy, simulations predict that the largest SM source is top-quark pair production with an additional radiated photon, t{bar t} + {gamma}. In the data we observe 16 t{bar t}{gamma} candidate events versus an expectation from non-top-quark SM sources of 11.2{sub -2.1}{sup +2.3}. Assuming the difference between the observed number and the predicted non-top-quark total is due to SM top quark production, we estimate the t{bar t} cross section to be 0.15 {+-} 0.08 pb.
Date: June 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Object Type: Article
System: The UNT Digital Library
Combined approach to the inverse protein folding problem. Final report (open access)

Combined approach to the inverse protein folding problem. Final report

The main scientific contribution of the project ''Combined approach to the inverse protein folding problem'' submitted in 1996 and funded by the Department of Energy in 1997 is the formulation and development of the idea of the multilink recognition method for identification of functional and structural homologues of newly discovered genes. This idea became very popular after they first announced it and used it in prediction of the threading targets for the CASP2 competition (Critical Assessment of Structure Prediction).
Date: June 1, 2000
Creator: Abagyan, Ruben A.
Object Type: Report
System: The UNT Digital Library
Direct observation of the strange b baryon Xi(b)- (open access)

Direct observation of the strange b baryon Xi(b)-

None
Date: June 1, 2007
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the Lambda(b)0 lifetime using semileptonic decays (open access)

Measurement of the Lambda(b)0 lifetime using semileptonic decays

None
Date: June 1, 2007
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the t anti-t production cross-section in p anti-p collisions using dilepton events (open access)

Measurement of the t anti-t production cross-section in p anti-p collisions using dilepton events

None
Date: June 1, 2007
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Search for a heavy resonance decaying into a Z+jet final state in p anti-p collisions at s**(1/2) = 1.96-TeV using the D0 detector (open access)

Search for a heavy resonance decaying into a Z+jet final state in p anti-p collisions at s**(1/2) = 1.96-TeV using the D0 detector

We have searched for a heavy resonance decaying into a Z+jet final state in p{bar p} collisions at a center of mass energy of 1.96 TeV at the Fermilab Tevatron collider using the D0 detector. No indication for such a resonance was found in a data sample corresponding to an integrated luminosity of 370 pb{sup -1}. We set upper limits on the cross section times branching fraction for heavy resonance production at the 95% C.L. as a function of the resonance mass and width. The limits are interpreted within the framework of a specific model of excited quark production.
Date: June 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Search for large extra spatial dimensions in dimuon production at D0 (open access)

Search for large extra spatial dimensions in dimuon production at D0

We present the results of a search for the e.ects of large extra spatial dimensions in p{bar p} collisions at {radical}s = 1.96 TeV in events containing a pair of energetic muons. The data correspond to 246 pb{sup -1} of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Good agreement with the expected background was found, yielding no evidence for large extra dimensions. We set 95% C.L. lower limits on the fundamental Planck scale between 0.85 TeV and 1.27 TeV within several formalisms. These are the most stringent limits achieved in the dimuon channel to date.
Date: June 1, 2005
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Search for long-lived particles decaying into electron or photon pairs with the D0 detector (open access)

Search for long-lived particles decaying into electron or photon pairs with the D0 detector

In this Letter we report on a search for long-lived particles that decay into final states with two electrons or photons. Such long-lived particles arise in a variety of theoretical models, like hidden valleys and supersymmetry with gauge-mediated breaking. By precisely reconstructing the direction of the electromagnetic shower we are able to probe much longer lifetimes than previously explored. We see no evidence of the existence of such long-lived particles and interpret this search as a quasi model-independent limit on their production cross section, as well as a limit on a long-lived fourth generation quark.
Date: June 1, 2008
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Search for Resonant Pair Production of long-lived particles decaying to b anti-b in p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

Search for Resonant Pair Production of long-lived particles decaying to b anti-b in p anti-p collisions at s**(1/2) = 1.96-TeV

We report on a first search for production of Higgs bosons decaying into neutral long-lived particles (NLLP) which each decay to a b{bar b} pair, using 3.6 fb{sup -1} of data recorded with the D0 detector at the Fermilab Tevatron collider. We search for pairs of displaced vertices in the tracking detector at radii in the range 1.6-20 cm from the beam axis. No significant excess is observed above background, and upper limits are set on the production rate in a hidden-valley benchmark model for a range of Higgs boson masses and NLLP masses and lifetimes.
Date: June 1, 2009
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type: Article
System: The UNT Digital Library
Development of Highly Durable and Reactive Regenerable Magnesium-Based Sorbents for CO2 Separation in Coal Gasification Process (open access)

Development of Highly Durable and Reactive Regenerable Magnesium-Based Sorbents for CO2 Separation in Coal Gasification Process

The specific objective of this project was to develop physically durable and chemically regenerable MgO-based sorbents that can remove carbon dioxide from raw coal gas at operating condition prevailing in IGCC processes. A total of sixty two (62) different sorbents were prepared in this project. The sorbents were prepared either by various sol-gel techniques (22 formulations) or modification of dolomite (40 formulations). The sorbents were prepared in the form of pellets and in granular forms. The solgel based sorbents had very high physical strength, relatively high surface area, and very low average pore diameter. The magnesium content of the sorbents was estimated to be 4-6 % w/w. To improve the reactivity of the sorbents toward CO{sub 2}, The sorbents were impregnated with potassium salts. The potassium content of the sorbents was about 5%. The dolomite-based sorbents were prepared by calcination of dolomite at various temperature and calcination environment (CO{sub 2} partial pressure and moisture). Potassium carbonate was added to the half-calcined dolomite through wet impregnation method. The estimated potassium content of the impregnated sorbents was in the range of 1-6% w/w. In general, the modified dolomite sorbents have significantly higher magnesium content, larger pore diameter and lower surface area, resulting …
Date: June 1, 2005
Creator: Abbasian, Javad; Khayyat, Armin Hassanzadeh & Slimane, Rachid B.
Object Type: Report
System: The UNT Digital Library
Colloid-Facilitated Plutonium Transport in Saturated Alluvium (open access)

Colloid-Facilitated Plutonium Transport in Saturated Alluvium

Natural groundwater colloids have been recognized as possible agents for enhancing the subsurface transport of strongly-sorbing radionuclides. To evaluate this mechanism, packed-bed column experiments were conducted comparing the simultaneous transport of dissolved plutonium (Pu), Pu sorbed onto natural colloids, 190-nm and 500-nm diameter fluorescent CML microspheres, and tritiated water in saturated alluvium. Experiments were conducted in two columns having slightly different porosities at two flow rates, resulting in average linear velocities (v{sub z}) of 0.6 to 3.65 cm/hr in one column and 0.57 to 2.85 cm/hr in the other. In all experiments, Pu associated with natural colloids transported through alluvium essentially unretarded, while dissolved Pu was entirely retained. These results were consistent with the strong sorption of Pu to alluvium and the negligible desorption from natural colloids, observed in separate batch experiments, over time scales exceeding those of the column experiments. Breakthroughs of natural colloids preceded tritiated water in all experiments, indicating a slightly smaller effective pore volume for the colloids. The enhancement of colloids transport over tritiated water decreased with v{sub z}, implying {approx} 40% enhancement at v{sub z} = 0. The 500-nm CML microspheres were significantly attenuated in the column experiments compared to the 190-nm microspheres, which exhibited …
Date: June 1, 2004
Creator: Abdel-Fattah, A.; Reimus, P.; Ware, S. & Haga, M.
Object Type: Report
System: The UNT Digital Library