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Anti-Lambda Polarization in High Energy pp Collisions withPolarized Beams

Description: We study the polarization of the anti-Lambda particle in polarized high energy pp collisions at large transverse momenta. The anti-Lambda polarization is found to be sensitive to the polarization of the anti-strange sea of the nucleon. We make predictions using different parameterizations of the polarized quark distribution functions. The results show that the measurement of longitudinal anti-Lambda polarization can distinguish different parameterizations, and that similar measurements in the transversely polarized case can give some insights into the transversity distribution of the anti-strange sea of nucleon.
Date: November 6, 2005
Creator: Xu, Qing-hua; Liang, Zuo-tang & Sichtermann, Ernst
Partner: UNT Libraries Government Documents Department

Mass, quark-number, and sqrt sNN dependence of the second andfourth flow harmonics in ultra-relativistic nucleus-nucleuscollisions

Description: We present STAR measurements of the azimuthal anisotropyparameter v_2 for pions, kaons, protons, Lambda, bar Lambda, Xi+bar Xi,and \Omega + bar Omega, along with v_4 for pions, kaons, protons, andLambda + bar Lambda at mid-rapidity for Au+Au collisions at sqrt sNN=62.4and 200 GeV. The v_2(p_T) values for all hadron species at 62.4 GeV aresimilar to those observed in 130 and 200 GeV collisions. For observedkinematic ranges, v_2 values at 62.4, 130, and 200 GeV are as little as10 percent-15 percent larger than those in Pb+Pb collisions at sqrt s NN=17.3 GeV. At intermediate transverse momentum (p_T from 1.5-5 GeV/c),the 62.4 GeV v_2(p_T) and v_4(p_T) values are consistent with thequark-number scaling first observed at 200 GeV. A four-particle cumulantanalysis is used to assess the non-flow contributions to pions andprotons and some indications are found for a smaller non-flowcontribution to protons than pions. Baryon v_2 is larger than anti-baryonv_2 at 62.4 and 200 GeV perhaps indicating either that the initialspatial net-baryon distribution is anisotropic, that the mechanismleading to transport of baryon number from beam- to mid-rapidity enhancesv_2, or that anti-baryon and baryon annihilation is larger in thein-plane direction.
Date: January 6, 2007
Creator: Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D. et al.
Partner: UNT Libraries Government Documents Department

Alignment validation

Description: The four experiments, ALICE, ATLAS, CMS and LHCb are currently under constructionat CERN. They will study the products of proton-proton collisions at the Large Hadron Collider. All experiments are equipped with sophisticated tracking systems, unprecedented in size and complexity. Full exploitation of both the inner detector andthe muon system requires an accurate alignment of all detector elements. Alignmentinformation is deduced from dedicated hardware alignment systems and the reconstruction of charged particles. However, the system is degenerate which means the data is insufficient to constrain all alignment degrees of freedom, so the techniques are prone to converging on wrong geometries. This deficiency necessitates validation and monitoring of the alignment. An exhaustive discussion of means to validate is subject to this document, including examples and plans from all four LHC experiments, as well as other high energy experiments.
Date: September 6, 2008
Creator: ALICE; ATLAS; CMS; LHCb & Golling, Tobias
Partner: UNT Libraries Government Documents Department


Description: The recent production and identification of isotopes of elements with atomic numbers up to six higher than the target element through bombardment with hexapositive 120-Mev carbon ions made it seem worthwhile to apply this technique to the transuranium region. Accordingly, small pieces of natural uranium metal (about 0.5 mil thick and 205 cm by 0.6 cm area) were irradiated in the internal carbon ion beam in the Berkeley 60-inch cyclotron. Following the irradiations, the uranium was dissolved in dilute hydrochloric acid containing hydrogen peroxide and a transplutonium fraction was isolated through the use of lanthanum fluoride, and lanthanum hydroxide precipitation steps followed by the ion exchange adsorption column procedure in which concentrated hydrochloric acid is used to separate the tripositive actinide elements from the rare earth elements. The transplutonium fractions in hydrochloric acid were evaporated as weightless films on platinum plates which were placed in the ionization chamber of the 48 channel pulse analyzer apparatus in order to measure the yield and energies of any alpha-particles which might be present. In the best experiment at about one hour after the end of the 90-minute bombardment, some 50 disintegrations per minute of the distinctive 7.1-Mev alpha-particles of Cf{sup 244} were observed to be present and to decay with the 45-minute half-life. The Cf{sup 244} was presumably formed by the reaction U{sup 238}(C{sup 12},6n). After the decay of the alpha-particles due to Cf{sup 244}, about five disintegrations per minute of alpha-particles with 6.8-Mev energy was observed and this alpha-radioactivity decayed with a half-life of about 35 hours. A consideration of the systematics of alpha-radioactivity leads us to the view that this activity is due to the new isotope Cf{sup 246} formed by the reaction U{sup 238}(C{sup 12},4n) . The measured half-life agrees with the expected alpha half-life for the observed energy for ...
Date: September 6, 1950
Creator: Ghiorso, A.; Thompson, S.G.; Street, K. Jr. & Seaborg, G.T.
Partner: UNT Libraries Government Documents Department

Grout Analysis for EC and CC Calorimeters

Description: The EC and CC calorimeters roll on Two parallel hardened steel ways which reside on the top of the D0 platform's center beam. The ways will be grouted to the center beam once their correct elevation has been established. The purpose of this report is to evaluate and compare three different epoxy grouts and their properties for this application.
Date: January 6, 1987
Creator: Engstrom, L.L.
Partner: UNT Libraries Government Documents Department

D0 Carriage Roller Bearing Measurements

Description: All of the ordered Tychoway rollers, to be used under the cryostat carriages on the center beam, have to be modified to accommodate a keyed way used to guide the cryostat along these same ways. A 0.320 x 0.406 inch notch is machined along one of the longer lower edges in order to create a 0.640 x 0.406 inch keyway when two of these notched rollers are bolted together (side by side) for installation. This keyway will fit over a .635 x .375 inch key, which is inserted into the ways. Due to the close fit, the rollers were sent to the Fermi Inspection Dept. to double check the machined notch dimensions and tolerances. Included is the drawing sent to the Tychoway manufacturer, who machined the notch, and the results of the measurements taken by the Inspection Dept. The tolerance on the 0.320 inch dimension is {+-} 0.002 inches. Only three of the initial ten rollers fall within the tolerance; No.3, 9 and 10 (they were numbered by the Inspection Dept.). The other seven, plus one of the 'good' rollers, can be matched up to meet the required dimensions of a 0.640 {+-} 0.004 inch keyway. Since only four rollers will be used on the keyed way per cryostat, the worst matches can be installed on the non-keyed side of the cryostat. A table listing the best possible matches and their subsequent dimensions and tolerances is given.
Date: February 6, 1989
Creator: Jaques, Al
Partner: UNT Libraries Government Documents Department

Inclusive hadron distributions in p+p collisions from saturation models of HERA DIS data.

Description: Dipole models based on various saturation scenarios provide reasonable fits to small-x DIS inclusive, diffractive and exclusive data from HERA. Proton un-integrated gluon distributions extracted from such fits are employed in a k{sub {perpendicular}}-factorization framework to calculate inclusive gluon distributions at various energies. The n-particle multiplicity distribution predicted in the Glasma flux tube approach shows good agreement with data over a wide range of energies. Hadron inclusive transverse momentum distributions expressed in terms of the saturation scale demonstrate universal behavior over a wider kinematic range systematically with increasing center of mass energies.
Date: December 6, 2010
Creator: Tribedy, P. & Venugopalan, R.
Partner: UNT Libraries Government Documents Department


Description: Sensitivities to neutrino oscillation parameters for possible very long baseline neutrino oscillation experiments are discussed. The reach for observing a non-zero mixing angle {theta}{sub 13}, establishing CP violation and determining the mass hierarchy are compared between various experimental options. Different possibilities for neutrino beams are briefly described, as well as the assumptions about the performance of a large water Cherenkov and liquid Argon detector.
Date: August 6, 2007
Partner: UNT Libraries Government Documents Department


Description: This paper summarizes the workshop presentations at the 2006 FFAG Workshop at KURRI related to FFAG use for muons. The particular topics covered were harmonic number jump acceleration, ionization cooling, PRISM and muon phase rotation, tracking and error analysis, and our understanding of scaling and non-scaling FFAGs.
Date: November 6, 2006
Creator: BERG,J.S.
Partner: UNT Libraries Government Documents Department


Description: It has been observed [1] that breakdown in an 805 MHz pill-box cavity occurs at much lower gradients as an external axial magnetic field is increased. This effect was not observed with on open iris cavity. It is proposed that this effect depends on the relative angles of the magnetic and maximum electric fields: parallel in the pill-box case; at an angle in the open iris case. If so, using an open iris structure with solenoid coils in the irises should perform even better. A lattice, using this principle, is presented, for use in 6D cooling for a Muon Collider. Experimental layouts to test this principle are proposed.
Date: August 6, 2007
Partner: UNT Libraries Government Documents Department

Cosmological Imprints of a Generalized Chaplygin Gas Model for the Early Universe

Description: We propose a phenomenological model for the early universe where there is a smooth transition between an early quintessence phase and a radiation-dominated era. The matter content is modeled by an appropriately modified Chaplygin gas for the early universe. We constrain the model observationally by mapping the primordial power spectrum of the scalar perturbations to the latest data of WMAP7. We compute as well the spectrum of the primordial gravitational waves as would be measured today. We show that the high frequencies region of the spectrum depends on the free parameter of the model and most importantly this region of the spectrum can be within the reach of future gravitational waves detectors.
Date: June 6, 2012
Creator: Bouhmadi-Lopez, Mariam; /Lisbon, CENTRA; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC; Liu, Yen-Wei & /Taiwan, Natl. Taiwan U.
Partner: UNT Libraries Government Documents Department

Constraining PCP Violating Varying Alpha Theory through Laboratory Experiments

Description: In this report we have studied the implication of a parity and charge-parity (PCP) violating interaction in varying alpha theory. Due to this interaction, the state of photon polarization can change when it passes through a strong background magnetic field. We have calculated the optical rotation and ellipticity of the plane of polarization of an electromagnetic wave and tested our results against different laboratory experiments. Our model contains a PCP violating parameter {beta} and a scale of alpha variation {omega}. By analyzing the laboratory experimental data, we found the most stringent constraints on our model parameters to be 1 {le} {omega} {le} 10{sup 13} GeV{sup 2} and -0.5 {le} {beta} {le} 0.5. We also found that with the existing experimental input parameters it is very difficult to detect the ellipticity in the near future.
Date: June 6, 2012
Creator: Maity, Debaprasad; /NCTS, Taipei /Taiwan, Natl. Taiwan U.; Chen, Pisin & /NCTS, Taipei /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
Partner: UNT Libraries Government Documents Department

(Small) Resonant non-Gaussianities: Signatures of a Discrete Shift Symmetry in the Effective Field Theory of Inflation

Description: We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson {pi} is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber. We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.
Date: June 6, 2012
Creator: Behbahani, Siavosh R.; /SLAC /Stanford U., Phys. Dept. /Boston U.; Dymarsky, Anatoly; /Princeton, Inst. Advanced Study; Mirbabayi, Mehrdad; /New York U., CCPP /New York U. et al.
Partner: UNT Libraries Government Documents Department

R^4 Counterterm and E_{7(7)} Symmetry in Maximal Supergravity

Description: The coefficient of a potential R{sup 4} counterterm in N = 8 supergravity has been shown previously to vanish in an explicit three-loop calculation. The R{sup 4} term respects N = 8 supersymmetry; hence this result poses the question of whether another symmetry could be responsible for the cancellation of the three-loop divergence. In this article we investigate possible restrictions from the coset symmetry E{sub 7(7)}/SU(8), using a double-soft scalar limit relation derived recently by Arkani-Hamed et al. In order to implement the relation, we make use of the fact that the R{sup 4} term occurs in the low-energy expansion of closed-string tree-level amplitudes. We find that the matrix elements of R{sup 4} that we investigated all obey the double-soft scalar limit relation, suggesting that E{sub 7(7)} is also respected by the R{sup 4} term.
Date: July 6, 2011
Creator: Broedel, Johannes; /Potsdam, Max Planck Inst. /Leibniz U., Hannover; Dixon, Lance J. & /SLAC
Partner: UNT Libraries Government Documents Department

Report for General Research July 10 to October 2, 1950 (Supporting Research Volume)

Description: The efficient prosecution of the research and process development on polonium, radium, actinium, waste disposal, and alpha-neutron sources requires the use of a wide variety of instrumental techniques such as: alpha, beta, gamma, and neutron counters and survey meters; emission, absorption, and mass spectroscopy: x-ray and electron diffraction; microbalances; and calorimeters. The complex and kaleidoscopic aspects of our research program require; (1) The application of standard instruments and techniques to a variety of problems; (2) The development of new techniques for the use of standard instruments; and (3) The development of new or improved Instruments. The sum of the above three categories constitutes the field of supporting research. The amplifier for counting pulses of wide dynamic range which was developed for counting beta particles in the presence of alphas has operated so satisfactorily that it has been decided to attempt to adopt it for neutron counting. Substantial improvement at medium counting rates has already been obtained but results at high counting rates are not as satisfactory. The development of a survey meter for monitoring fast neutrons has been under way for sometime. The attainment of higher efficiency has been attempted by the use of a dual-chambered counter tube. The tube operates with a filling of methane gas at two atmospheres pressure. The achievement of leak-proof seals and highest purity methane has been under investigation as their necessity has been indicated by tests. The development of a scintillation counter for surveying and measuring low levels of alpha activity has been continued. Recent efforts have been directed towards determining the correct voltages to be applied to the photomultiplier tube in order to operate under optimum conditions. Recent tests of the coincidence counter to detect scintillations in water containing alpha-active waste material have indicated the necessity of obtaining photomultiplier tubes with low noise ...
Date: November 6, 1950
Creator: Haring, M.M.
Partner: UNT Libraries Government Documents Department

High Energy Neutrino Signals from the Epoch of Reionization

Description: In this paper we perform a new estimate of the high energy neutrinos expected from GRBs associated with the first generation of stars in light of new models and constraints on the epoch of reionization and a more detailed evaluation of the neutrino emission yields. We also compare the diffuse high energy neutrino background from Population III stars with the one from ''ordinary stars'' (Population II), as estimated consistently within the same cosmological and astrophysical assumptions. In disagreement with previous literature, we find that high energy neutrinos from Population III stars will not be observable with current or near future neutrino telescopes, falling below both IceCube sensitivity and atmospheric neutrino background under the most extreme assumptions for the GRB rate. This rules them out as a viable diagnostic tool for these still elusive metal-free stars.
Date: July 6, 2007
Creator: Iocco, F.; Murase, K.; Nagataki, S. & Serpico, P.D.
Partner: UNT Libraries Government Documents Department

Bootstrapping Multi-Parton Loop Amplitudes in QCD

Description: The authors present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes e{sup +}e{sup -} {yields} Z, {gamma}* {yields} 4 jets and pp {yields} W + 2 jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely A{sub 5;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}) and A{sub 5;1}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup +}). Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}) and A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), which uses the previously-computed logarithmic parts of the amplitudes as input. They present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.
Date: July 6, 2005
Creator: Bern, Zvi; /UCLA; Dixon, Lance J.; /SLAC; Kosower, David A. & /Saclay, SPhT
Partner: UNT Libraries Government Documents Department

New simulation capabilities of electron clouds in ion beams with large tune depression

Description: We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D ''slice'' e-cloud code POSINST [M. Furman, this workshop, paper TUAX05], as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new ''drift-Lorentz'' particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX) [experimental results discussed by A. Molvik, this workshop, paper THAW02]. We describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC).
Date: June 6, 2006
Creator: Laboratory, Lawrence Livermore National
Partner: UNT Libraries Government Documents Department

Monte Carlo Particle Transport Capability for Inertial Confinement Fusion Applications

Description: A time-dependent massively-parallel Monte Carlo particle transport calculational module (ParticleMC) for inertial confinement fusion (ICF) applications is described. The ParticleMC package is designed with the long-term goal of transporting neutrons, charged particles, and gamma rays created during the simulation of ICF targets and surrounding materials, although currently the package treats neutrons and gamma rays. Neutrons created during thermonuclear burn provide a source of neutrons to the ParticleMC package. Other user-defined sources of particles are also available. The module is used within the context of a hydrodynamics client code, and the particle tracking is performed on the same computational mesh as used in the broader simulation. The module uses domain-decomposition and the MPI message passing interface to achieve parallel scaling for large numbers of computational cells. The Doppler effects of bulk hydrodynamic motion and the thermal effects due to the high temperatures encountered in ICF plasmas are directly included in the simulation. Numerical results for a three-dimensional benchmark test problem are presented in 3D XYZ geometry as a verification of the basic transport capability. In the full paper, additional numerical results including a prototype ICF simulation will be presented.
Date: November 6, 2006
Creator: Brantley, P S & Stuart, L M
Partner: UNT Libraries Government Documents Department

A General Nonlinear Fluid Model for Reacting Plasma-Neutral Mixtures

Description: A generalized, computationally tractable fluid model for capturing the effects of neutral particles in plasmas is derived. The model derivation begins with Boltzmann equations for singly charged ions, electrons, and a single neutral species. Electron-impact ionization, radiative recombination, and resonant charge exchange reactions are included. Moments of the reaction collision terms are detailed. Moments of the Boltzmann equations for electron, ion, and neutral species are combined to yield a two-component plasma-neutral fluid model. Separate density, momentum, and energy equations, each including reaction transfer terms, are produced for the plasma and neutral equations. The required closures for the plasma-neutral model are discussed.
Date: April 6, 2012
Creator: Meier, E T & Shumlak, U
Partner: UNT Libraries Government Documents Department

Energy Calibration of the BaBar EMC Using the Pi0 Invariant Mass Method

Description: The BaBar electromagnetic calorimeter energy calibration method was compared with the local and global peak iteration procedures, of Crystal Barrel and CLEO-II. An investigation was made of the possibility of {Upsilon}(4S) background reduction which could lead to increased statistics over a shorter time interval, for efficient calibration runs. The BaBar software package was used with unreconstructed data to study the energy response of the calorimeter, by utilizing the {pi}{sup 0} mass constraint on pairs of photon clusters.
Date: April 6, 2007
Creator: Tanner, David J. & U., /Manchester
Partner: UNT Libraries Government Documents Department

Effects of Cosmic Infrared Background on High Energy Delayed Gamma-Rays From Gamma-Ray Bursts

Description: Regenerated high energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the primary emission spectrum extends to TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The created high energy electron-positron pairs up-scatter not only cosmic microwave background (CMB) photons but also CIB photons, and secondary photons are generated in the GeV-TeV range. These secondary delayed photons may be observed in the near future, and useful for a consistency check for the primary spectra and GRB physical parameters. The up-scattered CIB photons cannot be neglected for low redshift bursts and/or GRBs with a relatively low maximum photon energy. The secondary gamma-rays also give us additional information on the CIB, which is uncertain in observations so far.
Date: April 6, 2007
Creator: Murase, Kohta; /Kyoto U., Yukawa Inst., Kyoto; Asano, Katsuaki; Japan, /Natl. Astron. Observ. of; Nagataki, Shigehiro & /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park
Partner: UNT Libraries Government Documents Department