7,045 Matching Results

Search Results

Results: 1 - 24 next
open access

Scaled Experimental Modeling of VHTR Plenum Flows

Description: Abstract The Very High Temperature Reactor (VHTR) is the leading candidate for the Next Generation Nuclear Power (NGNP) Project in the U.S. which has the goal of demonstrating the production of emissions free electricity and hydrogen by 2015. Various scaled heated gas and water flow facilities were investigated for modeling VHTR upper and lower plenum flows during the decay heat portion of a pressurized conduction-cooldown scenario and for modeling thermal mixing and stratification (“thermal st… more
Date: April 1, 2007
Creator: 15, ICONE
Partner: UNT Libraries Government Documents Department
open access

Development of Advanced Wear and Corrosion Resistant Systems Through Laser Surface Alloying and Materials Processing

Description: The stability of tungsten carbide particles in iron-rich and nickel-rich liquid during the laser surface alloying (LSA) process was investigated. Kinetic calculations indicate a rapid dissolution of tungsten carbide particles in iron-rich liquid, as compared with the dissolution rate in nickel-rich liquid. Optical microscopy indicated a heterogeneous microstructure around the tungsten particles that is in agreement with concentration gradients predicted by kinetic calculation. The work demonstr… more
Date: April 1, 2002
Creator: A, Babu S S Martukanitz R P Parks K D David S
Partner: UNT Libraries Government Documents Department
open access

Pressure-induced Breaking of Equilibrium Flux Surfaces in the W7AS Stellarator

Description: Calculations are presented for two shots in the W7AS stellarator which differ only in the magnitude of the current in the divertor control coil, but have very different values of experimentally attainable β (<β> ≈ 2.7% versus <β> ≈ 1.8%). Equilibrium calculations find that a region of chaotic magnetic field line trajectories fills approximately the outer 1/3 of the cross-section in each of these configurations. The field lines in the stochastic region are calculated to behave as if the flux sur… more
Date: April 24, 2007
Creator: A. Reiman, M.C. Zarnstorff, D. Monticello, A. Weller, J. Geiger, and the W7-AS Team
Partner: UNT Libraries Government Documents Department
open access

Impact of the LHC beam abort kicker prefire on high luminosity insertion and CMS detector performance

Description: The effect of possible accidental beam loss in LHC on the IP5 insertion elements and CMS detector is studied via realistic Monte Carlo simulations. Such beam loss could be the consequence of an unsynchronized abort or � in worst case � an accidental prefire of one of the abort kicker modules. Simulations with the STRUCT code show that this beam losses would take place in the IP5 inner and outer triplets. MARS simulations of the hadronic and electro-magnetic cascades induced in such an event ind… more
Date: April 13, 1999
Creator: A.I. Drozhdin, N.V. Mokhov and M. Huhtinen
Partner: UNT Libraries Government Documents Department
open access

On possible use of bent crystal to improve Tevatron beam scraping

Description: A possibility to improve the Tevatron beam halo scraping using a bent channeling crystal instead of a thin scattering primary collimator is studied. To evaluate the efficiency of the system, realistic simulations have been performed using the CATCH and STRUCT Monte Carlo codes. It is shown that the scraping efficiency can be increased and the accelerator-related backgrounds in the CDF and DØ collider detectors can be reduced by about one order of magnitude. Results on scraping efficiency versus… more
Date: April 8, 1999
Creator: A.I. Drozhdin, N.V. Mokhov and V.M. Biryukov
Partner: UNT Libraries Government Documents Department
open access

Radiation environment resulting from Main Injector beam extraction to the NuMI beam line

Description: A 120 GeV Main Injector proton beam will be delivered to the NuMI beam line at Fermilab at the rate of 3.7x 10{sup 20} per year. Realistic Monte Carlo simulations have been performed to examine the radiation environment in the beam extraction system and NuMI beam line elements. A complete 3-D model of the 160 meter extraction region has been implemented utilizing the computer code MARS. The model includes a description of the field of the electrostatic septa and POISSON calculated field maps of… more
Date: April 29, 1999
Creator: A.I. Drozhdin, P.W. Lucas, N.V. Mokhov, C.D. Moore and S.I. Striganov
Partner: UNT Libraries Government Documents Department
open access

A Rosetta Stone Relating Conventions In Photo-Meson Partial Wave Analyses

Description: A new generation of complete experiments in pseudoscalar meson photo-production is being pursued at several laboratories. While new data are emerging, there is some confusion regarding definitions of asymmetries and the conventions used in partial wave analyses (PWA). We present expressions for constructing asymmetries as coordinate-system independent ratios of cross sections, along with the names used for these ratios by different PWA groups.
Date: April 1, 2012
Creator: A.M. Sandorfi, B. Dey, A. Sarantsev, L. Tiator, R. Workman
Partner: UNT Libraries Government Documents Department
open access

Nonforward parton distributions

Description: Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive electroproduction processes require a generalization of usual parton distributions for the case when long-distance information is accumulated in nonforward matrix elements &lt;p{prime}{vert_bar}O(0,x){vert_bar}p&gt; of quark and gluon light-cone operators. They describe two types of nonperturbative functions parameterizing such matrix elements: double distributions F(x,y;t) and nonforward distribution funct… more
Date: April 1, 1997
Creator: A.Radyushkin
Partner: UNT Libraries Government Documents Department
open access

Images of Quark Intrinsic Motion in Covariant Parton Model

Description: We discuss the relations between TMDs and PDFs in the framework of the covariant parton model. The quark OAM and its connection to TMDs are studied as well.
Date: April 1, 2010
Creator: A.V. Efremov, P. Schweitzer, O.V. Teryaev, P. Zavada
Partner: UNT Libraries Government Documents Department
open access

EVALUATION OF TEMPORAL VARIATIONS IN HYDRAULIC CAPTURE DUE TO CHANGING FLOW PATTERNS USING MAPPING AND MODELING TECHNIQUES

Description: Robust performance evaluation represents one of the most challenging aspects of groundwater pump-and-treat (P&amp;T) remedy implementation. In most cases, the primary goal of the P&amp;T system is hydraulic containment, and ultimately recovery, of contaminants to protect downgradient receptors. Estimating the extent of hydraulic containment is particularly challenging under changing flow patterns due to variable pumping, boundaries and/or other conditions. We present a systematic approach to es… more
Date: April 7, 2011
Creator: AA, SPILIOTOPOULOS; LC, SWANSON; R, SHANNON & MJ, TONKIN
Partner: UNT Libraries Government Documents Department
open access

EFFECTS OF XE ION IRRADIATION AND SUBSEQUENT ANNEALING ON THE PROPERTIES OF MAGNESIUM-ALUMINATE SPINEL

Description: Single crystals of magnesium-aluminate spinel MgAl{sub 2}O{sub 4} were irradiated with 340 keV Xe{sup 2} ions at {minus}173 C ({approximately} 100 K). A fluence of 1 x 10{sup 20} Xe/m{sup 2} created an amorphous layer at the surface of the samples. The samples were annealed for 1 h at different temperatures ranging from 130 C to 880 C. Recrystallization took place in the temperature interval between 610 C and 855 C. Transmission electron microscopy (TEM) images show two distinct layers near the… more
Date: April 1, 2000
Creator: AFANASYEV, I. & AL, ET
Partner: UNT Libraries Government Documents Department
open access

GEOTHERMAL HEAT PUMP GROUTING MATERIALS

Description: The thermal conductivity of cementitious grouts has been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. The cement-sand grouts were also tested for rheological characteristics, bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environme… more
Date: April 1, 1998
Creator: ALLAN,M.
Partner: UNT Libraries Government Documents Department
open access

FUTURE PLANS AT BNL: RHIC-II AND eRHIC.

Description: The development of future facilities relevant to the study of deep inelastic scattering at BNL is described.
Date: April 16, 2007
Creator: ARONSON,S.
Partner: UNT Libraries Government Documents Department
open access

Hydrogen Storage Properties of Magnesium Base Nanostructured Composite Materials

Description: In this work, nanostructured composite materials have been synthesized using the mechanical alloying process. The new materials produced have been investigated by X-ray diffraction (XRD), transition electron microscope (TEM), scanning electron microscope (SEM) and electron energy dispersion spectrum (EDS) for their phase compositions, crystal structure, grain size, particle morphology and the distribution of catalyst element. Hydrogen storage capacities and the hydriding-dehydriding kinetics of… more
Date: April 30, 2004
Creator: AU, M
Partner: UNT Libraries Government Documents Department
open access

Search for Heavy, Long-Lived Neutralinos that Decay to Photons at CDF II Using Photon Timing

Description: The authors present the results of the first hadron collider search for heavy, long-lived neutralinos that decay via {tilde {chi}}{sub 1}{sup 0} {yields} {gamma}{tilde G} in gauge-mediated supersymmetry breaking models. Using an integrated luminosity of 570 {+-} 34 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV, they select {gamma}+jet+missing transverse energy candidate events based on the arrival time of a high-energy photon at the electromagnetic calorimeter as measured with a ti… more
Date: April 1, 2008
Creator: Aaltonen, T.; Adelman, J.; Akimoto, T.; Albrow, M. G.; Alvarez Gonzalez, B.; Amerio, S. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurement of Z gamma Production in pbar{p} Collisions at sqrt{s} = 1.96 TeV

Description: The production rate and kinematics of photons produced in association with Z bosons are studied using 2 fb{sup -1} of p{bar p} collision data collected at the Collider Detector at Fermilab. The cross section for p{bar p} {yields} {ell}{sup +}{ell}{sup -}{gamma} + X (where the leptons {ell} are either muons or electrons with dilepton mass M{sub {ell}{ell}} &gt; 40 GeV/c{sup 2}, and where the photon has transverse energy E{sub T}{sup {gamma}} &gt; 7 GeV and is well separated from the leptons) is … more
Date: April 1, 2010
Creator: Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Observation of Single Top Quark Production and Measurement of |Vtb| with CDF

Description: We report the observation of electroweak single top quark production in 3.2 fb{sup -1} of p{bar p} collision data collected by the Collider Detector at Fermilab at {radical}s = 1.96 TeV. Candidate events in the W+jets topology with a leptonically decaying W boson are classified as signal-like by four parallel analyses based on likelihood functions, matrix elements, neural networks, and boosted decision trees. These results are combined using a super discriminant analysis based on genetically ev… more
Date: April 1, 2010
Creator: Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Search for New Bottomlike Quark Pair Decays Q Q-Bar to (T W- ) (T-Bar W -) in Same-Charge Dilepton Events

Description: We report the most restrictive direct limits on masses of fourth-generation down-type quarks b{prime}, and quark-like composite fermions (B or T{sub 5/3}), decaying promptly to tW{sup {-+}}. We search for a significant excess of events with two same-charge leptons (e, {mu}), several hadronic jets, and missing transverse energy. An analysis of data from p{bar p} collisions with an integrated luminosity of 2.7 fb{sup -1} collected with the CDF II detector at Fermilab yields no evidence for such a… more
Date: April 2, 2012
Creator: Aaltonen, T.; Adelman, J.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurement of Particle Production and Inclusive Differential Cross Sections in p anti-p Collisions at s**(1/2) = 1.96-TeV

Description: We report a set of measurements of particle production in inelastic p{bar p} collisions collected with a minimum-bias trigger at the Tevatron Collider with the CDF II experiment. The inclusive charged particle transverse momentum differential cross section is measured, with improved precision, over a range about ten times wider than in previous measurements. The former modeling of the spectrum appears to be incompatible with the high particle momenta observed. The dependence of the charged part… more
Date: April 1, 2009
Creator: Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurement of $B_s^0 \to D_s^{(*)+} D_s^{(*)-}$ Branching Ratios

Description: The decays B{sub s}{sup 0} {yields} D{sub s}{sup (*)+}D{sub s}{sup (*)-}s are reconstructed in a data sample corresponding to an integrated luminosity of 6.8 fb{sup -1} collected by the CDF II detector at the Tevatron p{bar p} collider. All decay modes are observed with a significance of more than 10 {sigma}, and we measure the B{sub s}{sup 0} production rate times B{sub s}{sup 0} {yields} D{sub s}{sup (*)+} D{sub s}{sup (*)-} branching ratios relative to the normalization mode B{sup 0} {yields… more
Date: April 1, 2012
Creator: Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Search for the Rare Decays B^+ -> mu^+ mu^- K^+, B^0 -> mu^+ mu^- K^*0(892), and B^0_s -> mu^+ mu^- phi at CDF

Description: The authors search for b {yields} s{mu}{sup +}{mu}{sup -} transitions in B meson (B{sup +}, B{sup 0}, or B{sub s}{sup 0}) decays with 924 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. They find excesses with significances of 4.5, 2.9, and 2.4 standard deviations in the B{sup +} {yields} {mu}{sup +}{mu}{sup -}K{sup +}, B{sup 0} {yields} {mu}{sup +}{mu}{sup -}K*(892){sup 0}, and B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup … more
Date: April 1, 2008
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen