Search Results

Alignment of the Pixel and SCT Modules for the 2004 ATLAS Combined Test Beam

Description: A small set of final prototypes of the ATLAS Inner Detector silicon tracking system(Pixel Detector and SemiConductor Tracker), were used to take data during the 2004 Combined Test Beam. Data were collected from runs with beams of different flavour (electrons, pions, muons and photons) with a momentum range of 2 to 180 GeV/c. Four independent methods were used to align the silicon modules. The corrections obtained were validated using the known momenta of the beam particles and were shown to yield consistent results among the different alignment approaches. From the residual distributions, it is concluded that the precision attained in the alignmentof the silicon modules is of the order of 5 mm in their most precise coordinate.
Date: June 2, 2008
Creator: Ahmad, A.; Andreazza, A.; Atkinson, T.; Baines, J.; Barr, A. J.; Beccherle, R. et al.
Partner: UNT Libraries Government Documents Department

A computational model for coal transport and combustion

Description: In the period of March 1, 1992 to May 30, 1992 considerable progress has been made in the development of the stress transport model for rapid granular flows in a rotating frame of reference. The derivation of thermodynamically consistent constitutive equations were complete. It was shown that the model contains the existing kinetics theories as special limiting cases. The model predictions for the special case of rapid simple shear flows were evaluated and the results are compared with the simulation data. Progress also has been made in formulation of the thermodynamically consistent rate dependent model for turbulent two-phase flows. The thermodynamically admissible constitutive equations were derived, and the case of a simple shear flow was also studied. The kinetic model for rapid flows of granular materials, which includes frictional losses, was used and the special case of gravity flows down an inclined chute was studied. The computational modeling for rapid granular flows in complex geometries was further developed. The design for the experimental simple shear flow device was further improved, and the construction of the device has started.
Date: June 2, 1992
Creator: Ahmadi, G.
Partner: UNT Libraries Government Documents Department

A computational model for coal transport and combustion. Quarterly technical progress report, March 1, 1992--May 31, 1992

Description: In the period of March 1, 1992 to May 30, 1992 considerable progress has been made in the development of the stress transport model for rapid granular flows in a rotating frame of reference. The derivation of thermodynamically consistent constitutive equations were complete. It was shown that the model contains the existing kinetics theories as special limiting cases. The model predictions for the special case of rapid simple shear flows were evaluated and the results are compared with the simulation data. Progress also has been made in formulation of the thermodynamically consistent rate dependent model for turbulent two-phase flows. The thermodynamically admissible constitutive equations were derived, and the case of a simple shear flow was also studied. The kinetic model for rapid flows of granular materials, which includes frictional losses, was used and the special case of gravity flows down an inclined chute was studied. The computational modeling for rapid granular flows in complex geometries was further developed. The design for the experimental simple shear flow device was further improved, and the construction of the device has started.
Date: June 2, 1992
Creator: Ahmadi, G.
Partner: UNT Libraries Government Documents Department

Solubility of Phenothiazine in Water, Ethanol, and Propylene Glycol at (298.2 to 338.2) K and Their Binary and Ternary Mixtures at 298.2 K

Description: Article on the solubility of phenothiazine in water, ethanol, and propylene glycol at (298.2 to 338.2) K and their binary and ternary mixtures at 298.2 K.
Date: June 2, 2011
Creator: Ahmadian, Somaieh; Panahi-Azar, Vahid; Fakhree, Mohammad Amin Abolghassemi; Acree, William E. (William Eugene) & Jouyban, Abolghasem
Partner: UNT College of Arts and Sciences

STM imaging of electronic waves on the surface of Bi2Te3: topologically protected surface states and hexagonal warping effects

Description: Scanning tunneling spectroscopy studies on high-quality Bi{sub 2}Te{sub 3} crystals exhibit perfect correspondence to ARPES data, hence enabling identification of different regimes measured in the local density of states (LDOS). Oscillations of LDOS near a step are analyzed. Within the main part of the surface band oscillations are strongly damped, supporting the hypothesis of topological protec- tion. At higher energies, as the surface band becomes concave, oscillations appear which disperse with a particular wave-vector that may result from an unconventional hexagonal warping term.
Date: June 2, 2010
Creator: Alpichshev, Zhanybek; /SIMES, Stanford /SLAC /Stanford U., Phys. Dept.; Analytis, J.G.; /SIMES, Stanford /SLAC /Stanford U., Phys. Dept.; Chu, J.-H.; Fisher, I.R. et al.
Partner: UNT Libraries Government Documents Department

ARPES studies of the electronic structure of LaOFe(P,As)

Description: We report a comparison study of LaOFeP and LaOFeAs, two parent compounds of recently discovered iron-pnictide superconductors, using angle-resolved photoemission spectroscopy. Both systems exhibit some common features that are very different from well-studied cuprates. In addition, important differences have also been observed between these two ferrooxypnictides. For LaOFeP, quantitative agreement can be found between our photoemission data and the LDA band structure calculations, suggesting that a weak coupling approach based on an itinerant ground state may be more appropriate for understanding this new superconducting compound. In contrast, the agreement between LDA calculations and experiments in LaOFeAs is relatively poor, as highlighted by the unexpected Fermi surface topology around ({pi},{pi}). Further investigations are required for a comprehensive understanding of the electronic structure of LaOFeAs and related compounds.
Date: June 2, 2010
Creator: Analytis, J.G.
Partner: UNT Libraries Government Documents Department

Deprotection blue in extreme ultraviolet photoresists: influence of base loading and post-exposure bake temperture

Description: The deprotection blur of Rohm and Haas XP 5435, XP 5271, and XP5496 extreme ultraviolet photoresists has been determined as their base weight percent is varied. They have also determined the deprotection blur of TOK EUVR P1123 photoresist as the post-exposure bake temperature is varied from 80 C to 120 C. In Rohm and Haas XP 5435 and XP5271 resists 7x and 3x (respective) increases in base weight percent reduce the size of successfully patterned 1:1 line-space features by 16 nm and 8 nm with corresponding reductions in deprotection blur of 7 nm and 4 nm. In XP 5496 a 7x increase in base weight percent reduces the size of successfully patterned 1:1 line-space features from 48 nm to 38 nm without changing deprotection blur. In TOK EUVR P1123 resist, a reduction in post-exposure bake temperature from 100 C to 80 C reduces deprotection blur from 21 nm to 10 nm and reduces patterned LER from 4.8 nm to 4.1 nm.
Date: June 2, 2008
Creator: Anderson, Christopher N. & Naulleau, Patrick P.
Partner: UNT Libraries Government Documents Department

Don't always blame the photons: Relationships between deprotection blur, LER, and shot noise in EUV photoresists

Description: A corner rounding metric has been used to determine the deprotection blur of Rohm and Haas XP 5435, XP 5271, and XP 5496 extreme ultraviolet (EUV) photoresists as base weight percent is varied; an experimental open platform photoresist (EH27) as base weight percent is varied; and TOK EUVR P1123 and FUJI 1195 photoresists as post-exposure bake (PEB) temperature is varied. In the XP 5435, XP 5271, XP 5496, and EH27 resist platforms, a 6 times increase in base weight percent reduces the size of successfully patterned 1:1 lines by over 10 nm and lowers intrinsic line-edge roughness (LER) by over 2.5 nm without changing deprotection blur. In TOK EUVR P1123 photoresist, lowering the PEB temperature from 100 C to 80 C reduces measured deprotection blur (using the corner metric) from 30 nm to 20 nm and reduces the LER of 50 nm 1:1 lines from 4.8 nm to 4.3 nm. These data are used to drive a lengthy discussion about the relationships between deprotection blur, LER, and shot noise in EUV photoresists. We provide two separate conclusions: (1) shot noise is probably not the dominant mechanism causing the 3-4 nm EUV LER floor that has been observed over the past several years; (2) chemical contrast contributes to LER whenever deprotection blur is large relative to the printed half pitch.
Date: June 2, 2008
Creator: Anderson, Christopher N. & Naulleau, Patrick P.
Partner: UNT Libraries Government Documents Department

Measurement of the gamma gamma* -> pi0 transition form factor

Description: We study the reaction e{sup +}e{sup -} {yields} e{sup +}e{sup -}{pi}{sup 0} in the single tag mode and measure the differential cross section d{sigma}/dQ{sup 2} and the {gamma}{gamma}* {yields} {pi}{sup 0} transition form factor in the mometum transfer range from 4 to 40 GeV{sup 2}. At Q{sup 2} > 10 GeV{sup 2} the measured form factor exceeds the asymptotic limit predicted by perturbative QCD. The analysis is based on 442 fb{sup -1} of integrated luminosity collected at PEP-II with the BABAR detector at e{sup +}e{sup -} center-of-mass energies near 10.6 GeV.
Date: June 2, 2009
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Search for Dimuon Decays of a Light Scalar Boson in Radiative Transitions Y -> gamma A^0

Description: We search for evidence of a light scalar boson in the radiative decays of the {Upsilon}(2S) and {Upsilon}(3S) resonances: {Upsilon}(2S, 3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} {mu}{sup +}{mu}{sup -}. Such a particle appears in extensions of the Standaard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in the mass range 0.212 {<=} m{sub A{sup 0}} {<=} 9.3 GeV in the samples of 99 x 10{sup 6} {Upsilon}(2S) and 122 x 10{sup 6} {Upsilon}(3S) decays collected by the BABAR detector at the PEP-II B-factory and set stringent upper limits on the effective coupling of the b quark to the A{sup 0}. We also limit the dimuon branching fraction of the {eta}{sub b} meson: {Beta}({eta}{sub b} {yields} {mu}{sup +}{mu}{sup -}) < 0.9% at 90% confidence level.
Date: June 2, 2009
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Search for Dimuon Decays of a Light Scalar in Radiative Transitions Y(3S) -> gamma A0

Description: The fundamental nature of mass is one of the greatest mysteries in physics. The Higgs mechanism is a theoretically appealing way to account for the different masses of elementary particles and implies the existence of a new, yet unseen particle, the Higgs boson. We search for evidence of a light scalar (e.g. a Higgs boson) in the radiative decays of the narrow {Upsilon}(3S) resonance: {Upsilon}(3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} {mu}{sup +}{mu}{sup -}. Such an object appears in extensions of the Standard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in a sample of 122 x 10{sup 6} {Upsilon}(3S) decays collected by the BABAR collaboration at the PEP-II B-factory, and set 90% C.L. upper limits on the branching fraction product {Beta}({Upsilon}(3S) {yields} {gamma}A{sup 0}) x {Beta}(A{sup 0} {yields} {mu}{sup +}{mu}{sup -}) at (0.25 - 5.2) x 10{sup -6} in the mass range 0.212 {<=} m{sub A{sup 0}} {<=} 9.3 GeV. We also set a limit on the dimuon branching fraction of the {eta}{sub b} meson {Beta}({eta}{sub b} {yields} {mu}{sup +}{mu}{sup -}) < 0.8% at 90% C.L. The results are preliminary.
Date: June 2, 2009
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Search for the Rare Decays B+ to D(*)+K0s

Description: The authors report on the search for the rare decays B{sup +} {yields} D{sup (*)+} K{sub s}{sup 0} in approximately 226 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEp-II asymmetric-energy B factory at SLAC. They do not observe any significant signal and they set 90% confidence level upper limits on the branching fractions, {Beta}(B{sup +} {yields} D{sup +}K{sup 0}) < 0.5 x 10{sup -5} and {Beta}(B{sup +} {yields} D*{sup +} K{sup 0}) < 0.9 x 10{sup -5}.
Date: June 2, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department

Measurements of B to {pi, eta, eta'} l nu Branching Fractions andDetermination of |Vub| with Semileptonically Tagged B Mesons

Description: The authors report measurements of branching fractions for the decays B {yields} P{ell}{nu}{sub {ell}}, where P are the pseudoscalar charmless mesons {pi}{sup -}, {pi}{sup 0}, {eta} and {eta}{prime}, based on 348 fb{sup -1} of data collected with the BABAR detector, using B{sup 0} and B{sup +} mesons found in the recoil of a second B meson decaying as B {yields} D{sup (*)}{ell}{nu}{sub {ell}}. Assuming isospin symmetry, they combine pionic branching fractions to obtain {Beta}(B{sup 0} {yields} {pi}{sup -} {ell}{sup +} {nu}{sub {ell}}) = (1.54 {+-} 0.17{sub (stat)} {+-} 0.09{sub (syst)}) x 10{sup -4}; they find 3.2{sigma} evidence of the decay B{sup +} {yields} {eta}{ell}{sup +}{nu}{sub {ell}} and measure its branching fraction to be (0.64 {+-} 0.20{sub (stat)} {+-} 0.3{sub (syst)}) x 10{sup -4}, and determine {Beta}(B{sup +} {yields} {eta}{prime}{ell}{sup +}{nu}{sub {ell}}) < 0.47 x 10{sup -4} to 90% confidence level. Using partial branching fractions for the pionic decays in ranges of the momentum transfer and a recent form factor calculation, they obtain the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V{sub ub}| = (4.0 {+-} 0.5{sub (stat)} {+-} 0.2{sub (syst){sub -0.5}{sup +0.7}(theory)}) x 10{sup -3}.
Date: June 2, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Search for the B to K nu nu-bar Decay Using Semi-Leptonic Tags

Description: We present an update of the search for the flavor-changing neutral current B{sup +} {yields} K{sup +}{nu}{bar {nu}} decay using 351 X 10{sup 6} B{bar B} pairs collected at the {Upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B factory. Due to the presence of two neutrinos in the final state, we require the reconstruction of the companion B in the event through the decay channel B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}X. We find 38 candidates in the data with an expected background of 31{-+} 12. This allows us to set an upper limit on the branching fraction for B{sup +} {yields} K{sup +}{nu}{bar {nu}} of 4.5 X 10{sup -5} at 90% confidence level.
Date: June 2, 2010
Creator: Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Application of Nuclear Regulatory Commission Regulation Equivalency to Construction of New Nuclear Facilities

Description: The Spent Nuclear Fuels Project (SNFP) Office of the Department of Energy (DOE), Richland Operations Office, is charged with moving 2.100 metric tons of spent nuclear fuel elements left over from plutonium production into semi-permanent storage at DOE'S Hanford site in Washington state. In anticipation of eventual NRC regulation, the DOE decided to impose NRC requirements on new SNFP facility design and construction, specifically for the Cold Vacuum Drying Facility (CVDF) and the Canister Storage Building (CSB). The SNFP implemented this policy of ''NRC equivalency'' with the goal of achieving a level of nuclear safety equivalent to that of NRC-licensed fuel processing facilities. Appropriate features of the NRC licensing process were adopted. However, the SNFP maintained applicable DOE requirements in tandem with the NRC regulations. Project work is continuing, with the first fuel movement scheduled for November, 2000.
Date: June 2, 1999
Creator: BISHOP, G.E.
Partner: UNT Libraries Government Documents Department

Development and Testing of Low Cost Fuel Elements for Power Reactor Service

Description: The development of swaging and vibratory compaction process for fabrication of clad UO2 fuel rods is described. The cost is less than 50% of that for an equivalent core fabricated from pellets. The irradiation testing of vibratory filled and swaged UO2 rods is reported for burn-ups from 2,000 to 12,000 Mwd/t UO2; the results indicate that the rods are capable of excellent performance power reactors.
Date: June 2, 1961
Creator: Babcock & Wilcox Company
Partner: UNT Libraries Government Documents Department

RHIC Vertical AC Dipole Commissioning

Description: The RHIC vertical ac dipole was installed in the summer of 2001. The magnet is located in the interaction region between sector 3 and sector 4 common to both beams. The resonant frequency of the ac dipole was first configured to be around half of the beam revolution frequency to act as a spin flipper. At the end of the RHIC 2002 run, the ac dipole frequency was reconfigured for linear optics studies. A 0.35 mm driven betatron oscillation was excited with the vertical ac dipole and the vertical betatron functions and phase advances at each beam position monitor (BPM) around the RHIC yellow ring were measured using the excited coherence. We also recorded horizontal turn-by-turn beam positions at each BPM location to investigate coupling effects. Analysis algorithms and measurement results are presented.
Date: June 2, 2002
Creator: Bai, M.; DeLong, J.; Hoff, L.; Pai, C.; Peggs, S.; Piacentino, J. et al.
Partner: UNT Libraries Government Documents Department

RHIC Spin Flipper Commissioning.

Description: An ac dipole with horizontally oriented oscillating magnetic field (spin flipper) was installed in FU-IIC to reverse the spin direction in the presence of two full Siberian snakes, thereby reducing the systematic errors for the spin physics experiments in RHIC. With two full snakes, the spin vector completes one full precession around the vertical direction in two revolutions, and the spin depolarization resonances due to the machine imperfections and betatron oscillations are eliminated. Since the spin flipper provides an oscillating horizontal dipole field, a ''spin resonance'' can occur if the spin flipper frequency is placed in the neighborhood of the spin precession frequency [ 1,2,3]. By slowly sweeping the spin flipper frequency across the spin precession frequency, a full spin flip can be achieved. This paper reports the results of the FZUC spin flipper commissioned during the RHIC 2002 polarized proton run. By running the spin flipper at a slightly different configuration, one can also measure the spin precession tune.
Date: June 2, 2002
Creator: Bai, M.; Mackay, W. W.; Ranjbar, V. & Roser, T.
Partner: UNT Libraries Government Documents Department