R. D. Field

In this paper, we review recent theoretical progress and the latest experimental results in jet substructure from the Tevatron and the LHC. We review the status of and outlook for calculation and simulation tools for studying jet substructure. Following up on the report of the Boost 2010 workshop, we present a new set of benchmark comparisons of substructure techniques, focusing on the set of variables and grooming methods that are collectively known as 'top taggers'. To facilitate further exploration, we have attempted to collect, harmonize and publish software implementations of these techniques.

The eutectic high-entropy alloys (EHEAs) are a promising family of alloys for high-temperature application, while their high-temperature oxidation and the effect of refractory elements are not well known. In this work, the high-temperature oxidation of the Al19Fe20-xCo20-xNi41Mo2x (x = 0, 1, 2) EHEAs is investigated. The EHEA with no Mo addition forms a porous oxides scale with three layers and shows the lowest oxidation resistance. With minor addition of Mo, which can facilitate the selective oxidation of Al, the EHEA forms a dense and continuous oxides scale and has a significantly improved high-temperature oxidation resistance. With more Mo addition, the EHEA shows lower oxidation resistance due to the formation of volatile Mo oxides, which can evaporate and leave channels for oxygen. These results could be helpful in understanding the oxidation resistance of the Mo-containing HEAs.

An investigation of the change in slip behavior in NiAl with temperature has been conducted, with special emphasis on the 〈001〉 “hard” orientation. Single crystal specimens have been deformed in tension and compression in 〈110〉 and 〈001〉 orientations and extensive dislocation analysis performed in the TEM on the 〈001〉 oriented specimens. It was found that, although 〈111〉 slip can occur in RT compression of 〈001〉 oriented specimens, the increased tensile ductility observed at higher temperatures is due to the glide of b = 〈110〉 dislocations. The debris left behind by these dislocations consists of b = 〈100〉 dislocations, making identification of the operative Burgers vector difficult after any appreciable plastic strain. A mechanism for the formation of the b = 〈100〉 debris is presented. Nous avons étudié l'influence de la température sur le glissement dans NiAl, en prêtant une attention particulière à l'orientation “dure” 〈001〉. Des échantillons monocristallins ont été déformés en traction et en compression suivant les orientations 〈110〉 et 〈001〉, et une étude détaillée des dislocations a été réalisée par MET sur les échantillons d'orientation 〈001〉. Bien que le glissement 〈111〉 puisse être déclanché dans la compression à la température ambiante d'échantillons 〈001〉, l'accroissement de ductilité en traction observé aux températures élevées est dû au glissement de dislocations b = 〈110〉. Les débris laissés derrière elles par ces dislocations sont des dislocations b = 〈100〉, ce qui rend difficile l'identification du vecteur de glissement actif après toute déformation plastique appréciable. Nous présentons un mécanisme de formation de ces débris b = 〈100〉. Die Veränderung des Gleitverhaltens von NiAl mit der Temperatur wird mit besonderer Beachtung der “harten” 〈001〉-Orientierung untersucht. Einkristallproben werden in Zug und Druck in 〈110〉- und 〈001〉-Orientierung berformt; die Versetzungsstruktur der 〈001〉-Proben wird ausführlich im Elektronenmikroskop analysiert. Es wird gefunden, daß die bei höherer Temperatur beobachtete größere Duktilität im Zugversuch auf Gleitung von Versetzungen mit Burgersvektor b = 〈110〉 zurückgeht, wenngleich bei Raumtemperatur im Druckversuch 〈111〉-Gleitung auftreten kann. Das von diesen 〈110〉-Versetzungen hinterlassene Debris besteht aus Versetzungen mit b = 〈100〉, wodurch die Bestimmung der Burgersvektoren der gleitaktiven Versetzungen nach einiger plastischer Dehnung sehr erschwert ist. Ein Mechanismus der Bildung der Versetzungen mit b = 〈100〉 wird vorgeschlagen.

An investigation of the effect of alloying on slip behavior in NiAl as a function of temperature has been conducted. Single Cyrstal specimens have been deformed in tension and compression in 〈110〉 and 〈001〉 orientations. It was found that the addition of Cr and other alloying additions promote the activation of 〈111〉 slip over deformation by kinking in NiAl based alloys. This is believed to result from differential proportional hardening of the 〈100〉 vs 〈111〉 slip systems. No increase in RT tensile elongation is observed in these alloys. Increased tensile ductility observed at higher temperatures is due to the movement of b = 〈110〉 dislocations. Mous avons étudié en fonction de la température l'effet de l'addition d'éléments d'alliage sur le mode de glissement de NiAl. Des échantillons monocristallins ont été déformés en traction et en compression, suivant 〈110〉 et 〈001〉. L'addition de Cr et d'autres éléments d'alliage favorise l'activation du glissement 〈111〉 pendant la déformation par pliage dans les alliages à base de NiAl. Nous pensons que ceci est dû à un durcissement différentiel proportionnel pour les systèmes de glissement 〈100〉 par rapport aux systèmes 〈111〉. Dans ces alliages, aucun allongement en traction n'est observé à la température ambiante. L'accroissement de la ductilité en traction observé pour des températures supérieures est dû aux mouvements de dislocations b = 〈110〉. Der Einfluß legierender Elemente auf das Gleitverhalten von NiAl wird in Abhängigkeit von der Temperatur untersucht. Einkristrallproben werden im Zug- und im Druckversuch in 〈110〉- und 〈001〉-Richtung verformt. Zugaben von Cr und anderer legierender Elemente fördern die Aktivierung der 〈111〉-Gleitung gegenüber der Kinkbildung. Als Ursache wird angenommen, daß die 〈100〉-Gleitsysteme gegenüber den 〈111〉-Systemen differentiell und proportional verfestigt werden. Eine Zugverlängerung wird in diesen Legierungen bei Raumtemperatur nicht beobachtet. Die bei höherer Temperatur beobachtete erhöhte Zugduktilität rührt von der Bewegung von Versetzungen mit Burgersvektor b = 〈110〉 her.

Low-enriched uranium-10 wt.% molybdenum (LEU-10wt.%Mo) is of interest for the fabrication of monolithic fuels to replace highly-enriched uranium (HEU) dispersion fuels in high performance research and test reactors around the world. In this work, depleted uranium-10 wt.%Mo (DU-10wt.%Mo) is used to simulate the solidification and microstructural evolution of LEU-10wt.%Mo. Electron backscatter diffraction (EBSD) and complementary electron probe microanalysis (EPMA) reveal significant microsegregation present in the metastable γ-phase after solidification. Homogenization is performed at 800 and 1000 °C for times ranging from 1 to 32 h to explore the time–temperature combinations that will reduce the extent of microsegregation, as regions of higher and lower Mo content may influence local mechanical properties and provide preferred regions for γ-phase decomposition. We show for the first time that EBSD can be used to qualitatively assess microstructural evolution in DU-10wt.%Mo after homogenization treatments. Complementary EPMA is used to quantitatively confirm this finding. Homogenization at 1000 °C for 2–4 h may the regions that contain 8 wt.% Mo or lower, whereas homogenization at 1000 °C for longer than 8 h effectively saturates Mo chemical homogeneity, but results in substantial grain growth. The appropriate homogenization time will depend upon additional microstructural considerations, such as grain growth and intended subsequent processing. Higher carbon LEU-10wt.%Mo generally contains more inclusions within the grains and at grain boundaries after solidification. The effect of these inclusions on microstructural evolution (e.g. grain growth) during homogenization and as potential γ-phase decomposition nucleation sites is unclear, but likely requires additional study.

Etude par microscopie electronique a balayage, microsonde electronique et microscopie electronique analytique des alliages contenant 5, 10, 12, 5, 15, 20 et 25% at. Ti en substitution de Al

The effect of the self coupling of gluons on the direct photon spectrum in the decay ϒ(1s) → ggγ is estimated using a parton-shower Monte Carlo approximation to QCD perturbation theory. Outgoing gluons radiate additional gluons thereby developing an invariant mass which distorts the Dalitz plot for the decay resulting in photons of less energy than the “naive” massless gluon prediction. The correction to the “Born term” photon spectrum is sizable and is not very sensitive to the value of the QCD parameter Λ.

Two alloys of alumina dispersion-strengthened copper were subjected to 1-4 passes of equal channel angular extrusion (ECAE) by route BC. Microstructures before and after deformation were characterized by scanning electron microscopy, scanning ion microscopy and electron backscatter diffraction. Mechanical and electrical properties were evaluated using uniaxial tensile testing and the four point probe method, respectively. The initial microstructure consisted of cylindrical grains, elongated in the extrusion direction and highly textured in a <100>/<111> orientation. Following four ECAE passes, the average major axis of grains in both alloys decreased by over 50%, and the microstructure approached an equiaxed morphology. The texture decreased in intensity and shifted to a <112> orientation after one ECAE pass, followed by a transition to a <101> orientation by the fourth pass. Flow stress of AL-25 and AL-60 increased only 48 MPa (10%) and 24 MPa (5%), respectively, while the conductivity of both alloys remained essentially unchanged. A combination of Hall–Petch strengthening and texture softening are used to explain the observed changes in mechanical behavior.

We show that the inclusion of noncollinear gluon bremsstrahlung is essential in a quantum-chromodynamic (QCD) description of large transverse energy events in hadron-hadron collisions. Recent data from CERN and Fermilab for both large and small aperture energy triggers give indirect experimental support for QCD and for gluon bremsstrahlung effects.

The deformation behavior and fracture toughness of single crystals of the ordered intermetallic compound NiAl were investigated as functions of relatively low temperature thermal treatments. A strain aging embrittlement phenonenon, similar to that observed in mild steels, was identified. In the non-embrittled condition, tensile ductilities on the order of 7%–8% and fracture toughness values of 15–17 MPa m12 were obtained for crystals with a 〈110〉 axis tested at room temperature. Additional observations of serrated yielding during compression testing at temperatures between 100 and 200 °C are consistent with strain aging induced by the low temperature diffusion of interstitial impurities or constitutional vacancies to dislocations, thus rendering them immobile at room temperature.

The experiments at Run 2 of the Tevatron have each accumulated over 1 inverse femtobarn of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focussed on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.

A dynamical mechanism for the production of baryons in e+e− annihilations both on and off the upsilon resonance is presented. Parton showers are produced using an approximation to QCD perturbation theory. Color singlet clusters are formed and “decay” into hadrons through a simple phase-space process. Baryon-antibaryon pairs are produced in the decay of high mass clusters and are more abundant at the upsilon since the initial state of three gluons results in more high mass clusters than does the quark-antiquark initial state of the continuum.

We present a detailed examination of the heavy flavor properties of jets produced at the Fermilab Tevatron collider. The data set, collected with the Collider Detector at Fermilab, consists of events with two or more jets with transverse energy ET>~15GeV and pseudorapidity |η|<~1.5. The heavy flavor content of the data set is enriched by requiring that at least one of the jets (lepton-jet) contains a lepton with a transverse momentum larger than 8GeV/c. Jets containing hadrons with heavy flavor are selected via the identification of secondary vertices. The parton-level cross sections predicted by the HERWIG Monte Carlo generator program are tuned within theoretical and experimental uncertainties to reproduce the secondary-vertex rates in the data. The tuned simulation provides new information on the origin of the discrepancy between the bb¯ cross section measurements at the Tevatron and the next-to-leading order QCD prediction. We also compare the rate of away-jets (jets recoiling against the lepton-jet) containing a soft lepton (pT>~2GeV/c) in the data to that in the tuned simulation. We find that this rate is larger than what is expected for the conventional production and semileptonic decay of pairs of hadrons with heavy flavor.Received 2 December 2003DOI:https://doi.org/10.1103/PhysRevD.69.072004©2004 American Physical Society

This Report documents the results obtained by the Working Group on Quantum ChromoDynamics and the Standard Model for the Workshop ``Physics at TeV Colliders'', Les Houches, France, 21 May - 1 June 2001. The account of uncertainties in Parton Distribution Functions is reviewed. Progresses in the description of multiparton final states at Next-to-Leading Order and the extension of calculations for precision QCD observables beyond this order are summarized. Various issues concerning the relevance of resummation for observables at TeV colliders is examined. Improvements to algorithms of jet reconstruction are discussed and predictions for diphoton and photon pi-zero production at the LHC are made for kinematic variables of interest regarding searches for a Higgs boson decaying into two photons. Finally, several improvements implemented in Monte-Carlo event generators are documented.

The experiments at Run 2 of the Tevatron have each accumulated over 1 fb{sup -1} of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focused on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop.

We have developed a scanning magnetic microscope (SMM) based on a magnetic tunneling junction (MTJ) magnetoresistive (MR) sensor. The microscope is based on commercially available components employing two sets of scanning stages and a MTJ sensor. Spatial resolution and noise sensitivity were investigated using two MTJ sensors, one having high spatial resolution and the other low noise but coarser spatial resolution. We present measurements of magnetic field images from ferrite concentration calibration standards and a stainless steel welded specimen both imaged using a magnetoresistive scanning microscope. A sensitivity of ~ 10 μT/FN was obtained from standards with defined ferrite numbers (FN). This microscope represents a new powerful tool for the characterization and investigations of delta ferrite concentrations in stainless steel welded samples.

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

2nd workshop on the implications of HERA for LHC physics. Working groups: Parton Density Functions Multi-jet final states and energy flows Heavy quarks (charm and beauty) Diffraction Cosmic Rays Monte Carlos and Tools

Neural networks are used to help distinguish the $\mathrm{ZZ}\ensuremath{\rightarrow}{l}^{+}{l}^{\ensuremath{-}}$-jet-jet signal produced by the decay of a 400 GeV Higgs boson at a proton-proton collider energy of 15 TeV from the "ordinary" QCD $Z$+jets background. The ideal case where only one event at a time enters the detector (no pileup) and the case of multiple interactions per beam crossing (pileup) are examined. In both cases, when used in conjunction with the standard cuts, neural networks provide an additional signal-to-background enhancement.

We examine the feasibility of detecting in hadron-hadron collisions via the decay mode Z′ → WW → ℓν+jet+jet a new Z′ boson of the type suggested by E6 superstring models. We find that for a typical set of parameters the Z′ signal is nearly two order of magnitude smaller than the background for the production of single W bosons plus associated jets. We, therefore, conclude that such a Z′ cannot be observed in this decay mode at the present or planned hadron colliders.

B2 ordered NiAl is known for its poor room temperature (RT) ductility; failure occurs in a brittle like manner even in ductile single crystals deforming by single slip. In the present study NiAl was severely deformed at RT using the method of high pressure torsion (HPT) enabling the hitherto impossible investigation of multiple slip deformation. Methods of transmission electron microscopy were used to analyze the dislocations formed by the plastic deformation showing that as expected dislocations with Burgers vector a〈100〉 carry the plasticity during HPT deformation at RT. In addition, we observe that they often form a〈110〉 dislocations by dislocation reactions; the a〈110〉 dislocations are considered to be sessile based on calculations found in the literature. It is therefore concluded that the frequently encountered 3D dislocation networks containing sessile a〈110〉 dislocations are pinned and lead to deformation-induced embrittlement. In spite of the severe deformation, the chemical order remains unchanged.

A QCD parton-shower Monte Carlo model is used to simulate the production and decay of W bosons in hadron-hadron collisions at c.m. energies of 540 and 1600 GeV. In addition, fictitious narrow heavy W' bosons are generated at c.m. energies of 1600 and 40?0 GeV. The overall event topologies for both the leptonic and hadronic decay modes of the W and W' bosons are analyzed using jet and cluster techniques. The leptonic mode allows for a study of the jets produced by the initial-state parton showers, while an analysis of the hadronic mode enables us to place limits on the ability to reconstruct, from an examination of ``jets,'' the mass of the produced W or W' boson. Our results are equally valid for the production of heavy Z' bosons of the corresponding mass.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

We present parton-level analytical results for the next-to-leading order non-singlet virtual and real corrections to the Drell-Yan differential cross-section. The dependence of the differential cross section on the helicity of the initial state partons is shown explicitly (the spins of the final state partons are summed). The calculation is implemented in dimensional regularization within the $\bar{MS}$ scheme and with the t'Hooft Veltman prescriptions for the n-dimensional $\gamma_5$. Both the polarized initial state and the unpolarized cross sections can be obtained from our result. Our unpolarized cross section agrees with the previous result of Ellis, Martinelli and Petronzio in the non-singlet sector.

We present predictions for the non-singlet Drell-Yan longitudinal spin cross sections and spin asymmetry, $A_{LL}$, in proton-proton collisions at large $p_T$ at the RHIC energy of $200\gev$ at next-to-leading order QCD. The higher order corrections to the non-singlet polarized cross section, $\sigma_{NS}^{LL}$, are sizeable and similar to those found for the unpolarized cross section. The non-singlet asymmetry parameter, $A^{NS}_{LL}$, is very stable against higher order corrections and is a direct measurement of the non-singlet (i.e. valence) polarized quark distributions within the proton.

Recent data on the production of large-transverse-momentum (${p}_{T}$) pions and kaons in ${\ensuremath{\pi}}^{\ensuremath{-}}p$ and $\mathrm{pp}$ collisions at 200 GeV/c are examined and compared with the leading-order predictions of QCD. The theory gives an excellent qualitative description of all the features of the data including the large-${p}_{T}$ particle ratios, beam ratios, and angular dependence. In some cases, however, the predictions do not agree precisely with the data and the significance of this is discussed.

This Report documents the results obtained by the Working Group on Quantum ChromoDynamics and the Standard Model for the Workshop Physics at TeV Colliders'', Les Houches, France, 21 May - 1 June 2001. The account of uncertainties in Parton Distribution Functions is reviewed. Progresses in the description of multiparton final states at Next-to-Leading Order and the extension of calculations for precision QCD observables beyond this order are summarized. Various issues concerning the relevance of resummation for observables at TeV colliders is examined. Improvements to algorithms of jet reconstruction are discussed and predictions for diphoton and photon pi-zero production at the LHC are made for kinematic variables of interest regarding searches for a Higgs boson decaying into two photons. Finally, several improvements implemented in Monte-Carlo event generators are documented.

We irradiate the heavy fermion superconductors (U,Th)Be{sub 13} with high-energy heavy ions. Damage from the ions affects both heat capacity and magnetization measurements, although much less dramatically than in other superconductors. From these data and from direct imaging, we conclude that the irradiation does not create the amorphous columnar defects observed in high-temperature superconductors and other materials. We also find that the damage suppresses the two superconducting transitions of U{sub 0.97}Th{sub 0.03}Be{sub 13} by comparable amounts, unlike their response to other types of defects.

Abstract : The objective of this research was to evaluate the applicability of theoretical approaches based on first principles to understand the ductility problem in intermetallic compounds. The predictive approach is based on all electron total energy band structure calculations. Predictions were evaluated on single crystals of nickel aluminum alloys. Calculations of anti-phase boundary (APB) energy in binary NiAl and the effects of ternary alloying additions on APB energy were performed. Experimental work on the effects of Cr and V additions, predicted by the calculations to reduce APB energy, was conducted. Studies aimed at exploiting the stress induced martensite transformation in NiAl to increase low temperature toughness were also conducted. Results from the calculations were found to be in good agreement with known stoichiometric effects on the transformation in binary alloys and suggested potentially beneficial ternary and quaternary alloying additions. The investigation of the role of Chromium in promoting slip in NiAl was continued. Experiments to more fully understand this effect were performed. Additional calculations were conducted to clarify the stress induced martensite effect. Calculations aimed at understanding the role of charge density distributions and bond directionality in NiAl were also initiated. Work to determine the role of microalloying in promoting ductility in NiAl was initiated, through calculations of their effect on local charge distribution and experimental work to determine their effect on slip and fracture behavior.

The jet-jet profile, or detailed manner, in which transverse energy and mass are distributed around the jet-jet system resulting from the hadronic decay of a $Z$ boson in the process $\mathrm{Higgs}\mathrm{boson}\ensuremath{\rightarrow}\mathrm{ZZ}$ at a proton-proton collider energy of 40 TeV is carefully examined. Two observables are defined that can be used to help distinguish the ${l}^{+}{l}^{\ensuremath{-}}$-jet-jet signal from Higgs boson decay from the "ordinary" QCD background arising from the large transverse momentum production of single $Z$ bosons plus the associated jets. By making cuts on these observables, signal to background enhancement factors greater than 100 can be obtained.

Extract HTML view is not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button. Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005

Abstract An investigation of the microstructures of four U–Nb alloys has been conducted. The nominal Nb contents are 5, 9, 13 and 18at.% (approximately 2, 4, 5.5 and 8 wt%). The self-accommodating twin structures have been characterized and considered in terms of the lattice parameters of the martensite phases as well as the tetragonal distortion associated with the previously proposed intermediate γ0 phase. In addition, active deformation twinning systems during deformation of the U–13 at.% Nb shape-memory alloy have been identified and are discussed with respect to the α'' monoclinic distortion and ease of propagation in the microstructure.

Rene' 220C is a nickel base alloy with excellent castability. It is similar to alloy 718 but, due to its tantalum and cobalt content, it offers about a 50°C strength advantage. The replacement of iron with cobalt has also made the alloy immune to Laves phase formation, a critical advantage in large structural castings. The alloy can be regarded as a composite of dendritic and interdendritic areas, the latter containing heavy concentrations of crack arresting plates, with -y',(L12) and y,(D022), being the main strengthening phases in both dendritic and interdendritic areas. The plates actually consist of three phases: the orthorhombic delta, which is predominant, a DOlg, hexagonal phase and a rare DO24 hexagonal constituent. All are morphologically and chemically similar. (Nb, Ti) C and eutectic delta phases decorate the grain boundaries. As the formation of the plates rejects chromium, very small Cr2B and Cr5B3 phases nucleate on the plates during heat treatment and on subsequent exposure. The r', r, and plate phases, constitute up to 38 wt% of the alloy. The carbide and borides are very minor constituents. The 7' and 7 phases exhibit the same crystallographic relationships as in alloy 718. On prolonged exposure in the range of 650 to 815C, the alloy is completely stable in the lower temperature range, but subject to growth and subsequent solution of 7' and 7 and the precipitation of the phases at higher temperatures. After 1000 hrs. at 815C, little 7' and 7 remain, and the structure is transformed almost completely to various plate morphology phases, primarily delta. For up to 1,000 hrs. exposure in this temperature range, no precipitation of embrittling t.c.p. phases such as sigma or mu was observed. In addition, the MC carbides are completely stable and the less stable M23C6 and M6C phases do not form. This study was partially funded by USAF Contract F33657-846-2011.

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

The jet-jet profile methods that we developed to enhance the heavy Higgs boson \ensuremath{\rightarrow}ZZ signal over its backgrounds at a proton-proton collider energy of 40 TeV are extended to the heavy Higgs boson \ensuremath{\rightarrow}WW signal and backgrounds. The dominant background is now the pair production of top quarks via the subprocess gg\ensuremath{\rightarrow}tt\ifmmode\bar\else\textasciimacron\fi{}. The process qg\ensuremath{\rightarrow}Wq also contributes significantly, and backgrounds from the production of top quarks via the subprocess bg\ensuremath{\rightarrow}Wt and WW continuum are also included in the analysis but are less important. To enhance the signal, a profile analysis is performed on both the ``toward side'' (the W\ensuremath{\rightarrow}l\ensuremath{\nu} trigger side) and on the ``away side'' (the W\ensuremath{\rightarrow} jet-jet system). We define observables that help distinguish between the transverse energy distribution of the signal and of the backgrounds in an electromagnetic and/or hadronic calorimeter system. By making cuts on both the toward- and away-side observables, signal to background enhancement factors around 1000 can be obtained.

The Equal Channel Angular Extrusion (ECAE) technique has been applied to a P/M source Be alloy. Single and two-pass extrusions have been successfully completed, using two different processing routes, on Ni-canned billets of Be at 400 C. No cracking was observed in the billet and significant grain refinement was achieved. In this paper, microstructural features and dislocation structures are discussed for the single-pass material, including evidence of and dislocations. Significant crystallographic texture developed during ECAE, which will be discussed in terms of this unique deformation processing technique and the underlying physical processes which sustained the deformation.

Abstract There is a continued need within the aerospace and space communities to increase the structural efficiency of launch vehicles in order to increase the payload and/or lower fuel usage. Many of these structures have critical stiffness demands because of deflection, buckling, or acoustic/vibration damping. Aluminum-beryllium (Al-Be) is a candidate material for many such structural components because it has a very high stiffness to weight ratio (second only to pure beryllium) and has superior formability and weldability as compared to beryllium. The strength to weight ratio of commercial Al-Be is superior to aluminum alloys (7050 and 6061-T6) that are currently used for aerospace and space applications. Plasma spray forming of Al-Be alloys is being investigated at Los Alamos National Laboratory for producing axial symmetric components for aerospace and space applications. Plasma spray forming of beryllium and beryllium alloys was investigated during the 1960's and 70's by Union Carbide Speedway Laboratories and the Atomic Weapons Establishment for producing axial symmetric launch vehicle components for defense related applications. Information is presented on the thermal and mechanical properties of plasma sprayed AlBeMet which is a commercial Al-Be alloy produced by Brush Wellman Inc.

The authors present a phenomenological 'first look' at new Fermilab inclusive data on large p{sub {perpendicular}}{pi}{sup 0} production in pp and {pi}{sup +}p collisions at {theta}{sub cm} {approx} 90{sup o}. Predictions are made using a simple model in which particles are produced at large transverse momentum by a single, hard, large-angle scattering between quarks (q + q {yields} q + q). In this model the ratio R = {sigma}(pp {yields} {pi}{sup 0}X)/{sigma}({pi}{sup +}p {yields} {pi}{sup 0}X) is determined by the difference in the structure functions of the incident proton or pion. This interpretation is consistent with the new {theta}{sub cm} = 90{sup o} data and suggests the importance of measuring R at other {theta}{sub cm} values.

This report documents the results obtained by the Working Group on Quantum Chromodynamics and the Standard Model for the Workshop ''Physics at TeV Colliders,'' Les Houches, France, 26 May - 6 June 2003. After a Monte Guide description, the first contributions report on progress in describing multiple interactions, important for the LHC, and underlying events. An announcement of a Monte Carlo database, under construction, is then followed by a number of contributions improving parton shower descriptions. Subsequently, a large number of contributions address resummations in various forms, after which follow studies of QCD effects in pion pair, top quark pair and photon pair plus jet production. After a study of electroweak corrections to hadronic precision observables, the report ends by presenting recent progress in methods to compute finite order corrections at one-loop with many legs, and at two-loop.

We irradiate the heavy fermion superconductors (U,Th)Be_13 with high-energy heavy ions. Damage from the ions affects both heat capacity and magnetization measurements, although much less dramatically than in other superconductors. From these data and from direct imaging, we conclude that the irradiation does not create the amorphous columnar defects observed in high-temperature superconductors and other materials. We also find that the damage suppresses the two superconducting transitions of U_0.97Th_0.03Be_13 by comparable amounts, unlike their response to other types of defects.

We irradiate the heavy fermion superconductors (U,Th)Be_13 with high-energy heavy ions. Damage from the ions affects both heat capacity and magnetization measurements, although much less dramatically than in other superconductors. From these data and from direct imaging, we conclude that the irradiation does not create the amorphous columnar defects observed in high-temperature superconductors and other materials. We also find that the damage suppresses the two superconducting transitions of U_0.97Th_0.03Be_13 by comparable amounts, unlike their response to other types of defects.

This final report chronicles a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The High-Resolution Electron Microscopy Facility has doubled in size and tripled in quality since the beginning of the three-year period. The facility now includes a field-emission scanning electron microscope, a 100 kV field-emission scanning transmission electron microscope (FE-STEM), a 300 kV field-emission high-resolution transmission electron microscope (FE-HRTEM), and a 300 kV analytical transmission electron microscope. A new orientation imaging microscope is being installed. X-ray energy dispersive spectrometers for chemical analysis are available on all four microscopes; parallel electron energy loss spectrometers are operational on the FE-STEM and FE-HRTEM. These systems enable evaluation of local atomic bonding, as well as chemical composition in nanometer-scale regions. The FE-HRTEM has a point-to-point resolution of 1.6 {angstrom}, but the resolution can be pushed to its information limit of 1 {angstrom} by computer reconstruction of a focal series of images. HRTEM has been used to image the atomic structure of defects such as dislocations, grain boundaries, and interfaces in a variety of materials from superconductors and ferroelectrics to structural ceramics and intermetallics.

In an effort to better characterize and classify austenitic stainless steel resistance upset welds, standard methods have been examined and alternative methods investigated. Optical microscopy yields subjective classification due to deformation obscured bond lines and individual perception. The use of specimen preparations that better reveal grain boundaries aids in substantiating optical information. Electron microscopy techniques produce quantitative information in relation to microstructural constituents. Orientation Imaging Microscopy (OIM) is a relatively new technique for obtaining objective, quantitative information pertaining to weld integrity, i.e., percent grain boundary growth across the interface.

We present parton-level analytical results for the next-to-leading order non-singlet virtual corrections to the Drell-Yan differential cross section. The dependence of the differential cross section on the helicity of the initial state partons is shown explicitly (the spins of the final state partons are summed). The calculation is implemented in dimensional regularization within the {ovr MS} scheme and with the t`Hooft Veltman prescriptions for the n-dimensional {gamma}{sub 5}. Both the polarized initial state and the unpolarized cross sections can be obtained from our result. Our unpolarized cross section agrees with the previous result of Ellis, Martinelli and Petronzio in the non-singlet sector. 13 refs., 4 figs.

We investigate the event signature of the {ell}{nu}b{bar b}q{bar q} decay mode of top-pair production in proton-antiproton collisions at 1.8 TeV. Neural networks and Fisher discriminates are used in conjunction with modified Fox-Wolfram {open_quotes}shape{close_quotes} variables to help distinguish the top-pair signal from the W + jets and b{bar b}+jets background. Instead of requiring at least four jets in the event, we find that it is faster and better to simply cut on the number of calorimeter cells with transverse energy greater than some minimum. By combining these cell cuts with the event shape information, we are able to obtain a signal to background ratio of around 9 while keeping 30% of the signal. This corresponds to a signal to background enhancement of around 370.

We examine jet shapes in the forward region, {eta}(jet) > 4, of 40 TeV proton-proton collisions and compare them with 90{degree} jets. In the laboratory, forward jets are Lorentz contracted into thin ``disks.`` For example, a jet which at {theta}{sub cm}(jet) = 90{degree} would have its particles located within a ``cone`` with angular widths {Delta}{theta}{sub cm} = {Delta}{phi} = 28{degree} (i.e., 0.5 radians), if ``boosted`` to {eta}(jet) = 4 ({theta}{sub cm} = 2{degree}) becomes a ``disk`` with an angular width of {Delta}{theta}{sub cm} = 1{degree}! Jet shapes are roughly invariant when plotted versus pseudorapidity, {eta}, and azimuthal angle, {phi}. In addition, we examine how well the electromagnetic component (i.e., photons and electrons) of a jet ``tracks`` the true position of the jet.

A Ni-base su,peralloy containing 13%Al-9%Mo-Z%Ta (in at.%) has been characterized in both the rapidly solidified condition and after dynamic compaction.Dynamically compacted specimens were examined in the ascompacted condition and observations related to current theories of interparticle boniding.In addition, the recrystallization behavior of the compacted material at relatively low temperature (~0.5 -0.75 T,) was investigated.

Neural networks are used to help distinguish the ZZ {yields} {ell}{sup +}{ell}{sup {minus}}-jet-jet signal produced by the decay of a 400 GeV Higgs boson at a proton-proton collider energy of 15 TeV from the ``ordinary`` QCD Z + jets background. The ideal case where only one event at a time enters the detector (no pile-up) and the case of multiple interactions per beam crossing (pile-up) are examined. In both cases, when used in conjunction with the standard cuts, neural networks provide an additional signal to background enhancement.