The authors discuss the phenomenology of a light U(1) gauge boson, {gamma}{sub B}, that couples only to baryon number. Gauging baryon number at high energies can prevent dangerous baryon-number violating operators that may be generated by Planck scale physics. However, they assume at low energies that the new U(1) gauge symmetry is spontaneously broken and that the {gamma}{sub B} mass m{sub B} is smaller than m{sub z}. They show for m{sub {Upsilon}} < m{sub B} < m{sub z} that the {gamma}B coupling {alpha}{sub B} can be as large as {approximately} 0.1 without conflicting with the current experimental constraints. The authors argue that {alpha}{sub B} {approximately} 0.1 is large enough to produce visible collider signatures and that evidence for the {gamma}{sub B} could be hidden in existing LEP data. They show that there are realistic models in which mixing between the {gamma}{sub B} and the electroweak gauge bosons occurs only as a radiative effect and does not lead to conflict with precision electroweak measurements. Such mixing may nevertheless provide a leptonic signal for models of this type at an upgraded Tevatron.

Structural distortions that compete with superconductivity have been investigated in two systems where oxygen content can be used to vary the doping continuously from the under doped state, through the maximum T{sub c} into the over doped state. In the 123 system, (La{sub 1{minus}x}Ca{sub x})(Ba{sub 1.75{minus}x}La{sub 0.25+x})Cu{sub 3}O{sub 7+{delta}}, the buckling of the CuO{sub 2} planes goes through a maximum at the maximum T{sub c}. In HgBa{sub 2}CuO{sub 4+{delta}}, where buckling of the CuO{sub 2} planes is not available as a structural degree of freedom, there is a plateau at the maximum T{sub c} where the unit cell volume expands as oxygen is added while the charge transfer and T{sub c} remain constant. These unusual structural phenomena upon crossing through the maximum T{sub c} are hypothesized to be a response of the crystal structure to the electronic structure, with the structural distortions competing with superconductivity, or lowering the T{sub c} from what it would otherwise be.

The complexity of large-scale scientific simulations often necessitates the combined use of multiple software packages developed by different groups in areas such as adaptive mesh manipulations, scalable algebraic solvers, and optimization. Historically, these packages have been combined by using custom code. This practice inhibits experimentation with and comparison of multiple tools that provide similar functionality through different implementations. The ALICE project, a collaborative effort among researchers at Argonne National Laboratory, is exploring the use of component-based software engineering to provide better interoperability among numerical toolkits. They discuss some initial experiences in developing an infrastructure and interfaces for high-performance numerical computing.

A class of planar microstructure is proposed which provide high accelerating gradients when excited by an infrared laser pulse. These structures consist of parallel dielectric slabs separated by a vacuum gap; the dielectric or the outer surface coating are spatially modulated at the laser wavelength along the beam direction so as to support a standing wave accelerating field. We have developed numerical and analytic models of the accelerating mode fields in the structure. We show an optimized coupling scheme such that this mode is excited resonantly with a large quality factor. The status of planned experiments on fabricating and measuring these planar structures will be described.

Orbit correction is now routinely performed at the few-micron level in the Advanced Photon Source (APS) storage ring. Three diagnostics are presently in use to measure and control both AC and DC orbit motions: broad-band turn-by-turn rf beam position monitors (BPMs), narrow-band switched heterodyne receivers, and photoemission-style x-ray beam position monitors. Each type of diagnostic has its own set of systematic error effects that place limits on the ultimate pointing stability of x-ray beams supplied to users at the APS. Limiting sources of beam motion at present are magnet power supply noise, girder vibration, and thermal timescale vacuum chamber and girder motion. This paper will investigate the present limitations on orbit correction, and will delve into the upgrades necessary to achieve true sub-micron beam stability.

Detection of molecular ions in mass spectrometry is typically accomplished by an ion colliding with a surface and then amplifying the emitted secondary electrons. It is well established that the secondary electron yield decreases as the mass of the primary ion increases [1-3], thus limiting the detection efficiency of large molecular ions. One way around this limitation is to use secondary ion detectors because the emission efficiency of secondary ions does not seem to decrease for increasing primary ion mass [1]. However this technique has limitations in timing resolution because of the mass spread of the emitted secondary ions. To find other ways around high mass detection limitations it is important to understand existing mechanisms of detection and to explore alternative detector types. To this end, a superconducting tunnel junction (STJ) detector was used in measuring the secondary electron emission efficiency, se, for a MCP detector. STJ detectors are energy sensitive and do not rely on secondary emission to produce a signal. Using a linear MALDI-TOF mass spectrometer, a STJ detector is mounted directly behind the hole in an annular MCP detector. This mounting arrangement allows ions to be detected simultaneously by each detector. The STJ detector sits in a …

The Chemical Weapons Convention (CWC) contains the most extensive verification inspection provision of any arms control agreement in history. Among its innovations are provisions for facility agreements to govern on-site verification inspections of certain facilities. A facility agreement is an agreement or arrangement between a State Party and the Organization [for the Prohibition of Chemical Weapons] relating to a specific facility subject to on-site verification pursuant to Articles 4, 5 and 6. The purpose of this very brief paper is to discuss the value of specificity in the model facility agreements that are to serve as the basis for facility agreements. The views expressed herein are those of the author alone, and not necessarily those of the government of the US of America or any other institution. The model facility agreements are a key document to national implementation of the CWC. As explained in the Manual for National Implementation of the Chemical Weapons Convention, facility agreements are among the important protections the CWC provides for confidential business information at facilities subject to CWC inspections. Thus, the structure of the models for these agreements will fundamentally determine how national implementation of the Convention will affect various private firms. A particularly salient …

Some issues are presented on the rf system in the future Fermilab prebooster, which accelerates 4 bunches each containing 0.25 x 10{sub 14} protons from 1 to 3 GeV kinetic energy. The problem of beam loading is discussed. The proposal of having a non-tunable fixed-frequency rf system is investigated. Robinson's criteria for phase stability are checked and possible Robinson instability growth is computed.

We have studied the restoration of chiral symmetry in lattice QCD at the finite temperature transition from hadronic matter to a quark-gluon plasma. By measuring the screening masses of flavour singlet and non-singlet meson excitations, we have seen evidence that, although flavour chiral symmetry is restored at this transition, flavour singlet (U(1)) axial symmetry is not. We conclude that this indicates that instantons continue to play an important role in the quark-gluon plasma phase.

We have examined the weathered surfaces of 720 year old Hawaiian basalt glasses that were recovered from a subaerial environment with high-resolution transmission electron microscopy (TEM) and energy filtered imaging and electron energy loss spectroscopy (EELS) techniques. Whereas the alteration products (palagonite) were physically detached from the underlying glass in most samples, a gel-like amorphous layer was observed adjacent to the glass in a few samples. To our knowledge, this is the first time a gel layer has been observed on weathered basalt. This is significant because analogous gel layers have been observed on nuclear waste glasses reacted in laboratory tests, and this demonstrates an important similarity in the mechanisms of the weathering of basalt and the corrosion of waste glasses.

The Soudan 2 detector is used to search for evidence of nucleon decay. Particular emphasis is put on searches for modes with multiple-charged particles in the final state, and for modes suggested by super-symmetric theories.

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CDF and D0 have collected a huge number of B meson during 1992-1993 collider run. The major results on B lifetimes, rare decays and B{sup o} - {bar B}{sup o} mixing will be here reviewed. The first measurement of time dependent mixing at hadron collider is also presented.

The atmospheric corrosion of oxygen-free copper (CDA-102), 70/30 copper-nickel (CDA-715), and 7% aluminum bronze (CDA-613) in an irradiated moist air environment was investigated. Experiments were performed in both dry and 40% RH (@90{degree}C) air at temperatures of 90 and 150{degree}C. Initial corrosion rates were determined based on a combination of weight gain and weight loss measurements. Corrosion products observed were identified. These experiments support efforts by the Yucca Mountain Project (YMP) to evaluate possible metallic barrier materials for nuclear waste containers. 8 refs., 1 fig., 2 tabs.

Expressions for fields due to a point charge in 3D and due to a line charge in 2D are compared. Extensions to dipoles are made with emphasis on the relationship between dipole orientation and field component magnitudes. Differences between the effects on fields of dipole rotations in 2D and in 3D are highlighted and formulas for maximizing individual field components are given. A final macrogeometry extension is made and a closed-form expression is developed to calculate the field due to an arbitrary 3D configuration of permanent magnet (PM) blocks. The field optimization theory is applied to the design of the ALS elliptically polarizing undulator (EPU). Utilizing 3D field enhancement, peak on-axis field in practical designs can be increased typically by 5% to 40% or more over their 2D counterparts. The theory is generally applicable to any pure (i.e., no soft magnetic material) PM design.

Mixed-conducting (electronic and ionic conducting) dense ceramics are used in many applications, including fuel cells, gas separation membranes, batteries, sensors, and electrocatalysis. This paper describes mixed-conducting ceramic membranes that are being developed to selectively remove oxygen and hydrogen from gas streams in a nongalvanic mode of operation (i.e., with no electrodes or external power supply). Ceramic membranes made of Sr-Fe-Co oxide (SFC), which exhibits high combined electronic and oxygen ionic conductivities, can be used for high-purity oxygen separation and/or partial oxidation of methane to synthesis gas (syngas, a mixture of CO and H{sub 2}). The electronic and ionic conductivities of SFC were found to be comparable in magnitude. Steady-state oxygen permeability of SFC has been measured as a function of oxygen-partial-pressure gradient and temperature. For an {approx}3-mm-thick membrane, the oxygen permeability was {approx}2.5 scc{center_dot}cm{sup {minus}2}{center_dot}min{sup {minus}1} at 900 C. Oxygen permeation increases as membrane thickness decreases. Tubular SFC membranes have been fabricated and operated at 900 C for {approx}1000 h in converting methane into syngas. The oxygen permeated through the membrane reacted with methane in the presence of a catalyst and produced syngas. We also studied the transport properties of yttria-doped BaCeO{sub 3{minus}{delta}} (BCY) by impedance spectroscopy and open-cell voltage …

Fermilab experiment E866 has performed a precision measurement of the ratio of Drell-Yan yields from 800 GeV/c protons incident on deuterium and hydrogen targets. The measurement is used to determine the ratio of down antiquarks({bar d}) to up antiquarks({bar u}) in the proton over a broad range in the fraction of the proton momentum carried by the antiquark, 0.02 &lt; x &lt; 0.345. For x &lt; 0.15, the data is in reasonable agreement with pre-existing parton distributions while for x &gt; 0.20 the data is much closer to unity than these parton functions had indicated. The light quark asymmetry provides valuable information on the relative role perturbative and non-perturbative mechanisms play in generating the nucleon sea. A proposal to extend the Drell-Yan measurement to higher values of x using 120 GeV protons from the Fermilab main injector will be discussed.

A generic vibratory-response modeling program has been developed as a tool for designing high-precision optical positioning systems. Based on multibody dynamics theory, the system is modeled as rigid-body structures connected by linear elastic elements, such as complex actuators and bearings. The full dynamic properties of each element are determined experimentally or theoretically, then integrated into the program as inertial and stiffness matrices. Utilizing this program, the theoretical and experimental verification of the vibratory behavior of a double-multilayer monochromator support and positioning system is presented. Results of parametric design studies that investigate the influence of support floor dynamics and highlight important design issues are also presented. Overall, good matches between theory and experiment demonstrate the effectiveness of the program as a dynamic modeling tool.

The scanning transmission electron microscope (STEM) provides a route for the determination of interface structure and bonding directly from experimental data. Through an annular detector, Z-contrast images reveal atomic column locations without prior knowledge. The incoherent nature of such images allows a direct structure inversion through a maximum entropy analysis. The Z-contrast image also facilitates atomic-resolution spectroscopy by allowing the probe to be positioned with atomic precision. With this combination of atomic-resolution imaging and spectroscopy, structural units for [001] tilt grain boundaries in SrTiO{sub 3} were identified. All units revealed the presence of half-filled columns, an efficient way to overcome the problem of like-ion repulsion in ionic materials. With the 1.3 {angstrom} probe of the 300-kV STEM, an unexpected core structure has been found for Lomer dislocations at a CdTe/ GaAs [001] interface, while 60{degrees} dislocations were directly identified to be of glide type.

Classical mechanics is based upon a mechanical picture of nature that is fundamentally incorrect. It has been replaced at the basic level by a radically different theory: quantum mechanics. This change entails an enormous shift in one`s basic conception of nature, one that can profoundly alter the scientific image of man himself. Self-image is the foundation of values, and the replacement of the mechanistic self-image derived from classical mechanics by one concordant with quantum mechanics may provide the foundation of a moral order better suited to today`s times, a self-image that endows human life with meaning, responsibility, and a deeper linkage to nature as a whole.

The medical applications for ultra short pulse lasers (USPLs) and their associated commercial potential are reviewed. Short pulse lasers offer the surgeon the possibility of precision cutting or disruption of tissue with virtually no thermal or mechanical damage to the surrounding areas. Therefore the USPL offers potential improvement to numerous existing medical procedures. Secondly, when USPLs are combined with advanced tissue diagnostics, there are possibilities for tissue-selective precision ablation that may allow for new surgeries that cannot at present be performed. Here we briefly review the advantages of short pulse lasers, examine the potential markets both from an investment community perspective, and from the view. of the technology provider. Finally nominal performance and cost requirements for the lasers, delivery systems and diagnostics and the present state of development will be addressed.

The development of hydrogen transport ceramic membranes offers increased opportunities for hydrogen gas separation and utilization. Commercial application of such membranes will most likely take place under conditions of elevated temperature and pressure, where industrial processes producing and or utilizing hydrogen occur, and where such membranes are theoretically expected to have the greatest permeability. Hydrogen separation membrane performance data at elevated temperature is quite limited, and data at elevated pressures is conspicuously lacking. This paper will describe the design, construction, and recent experimental results obtained from a membrane testing unit located at the U.S. Department of Energy's Federal Energy Technology Center (FETC). The membrane testing unit is capable of operating at temperatures up to 900 C and pressures up to 500 psi. Mixed-oxide ceramic ion-transport membranes, fabricated at Argonne National Laboratory (ANL), were evaluated for hydrogen permeability and characterized for surface changes and structural integrity using scanning electron microscopy/X-ray microanalysis (SEM/EDS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), as a function of temperature, pressure, and hydrogen exposure.

We present results which show lasing at 79 {Angstrom} in nickel-like neodymium (Z=60) when a series of short 100--150 ps pulses which are 400--500 ps apart are used to illuminate slab targets of neodymium. This multiple pulse technique was first used successfully with germanium and selenium targets where strong lasing was observed on the neon-like 3p {yields} 3s(J=0{yields}1) transitions at 196 and 182 {Angstrom}, respectively. We also will present results which use this technique on both higher and lower Z targets of neon-like ions. For the higher-Z ions such as yttrium, zirconium, and molybdenum we observe the usual lasing dominated by the pair of 3p {yields} 3s(J=2{yields}1) transitions as seen in other experiments using single pulse illumination. For lower-Z ions such as iron, nickel and zinc we see dominant lasing from the 3p {yields} 3s(J=0{yields}1) transition however it is relatively weak for iron and increases with Z to become quite strong for zinc. We present results which show the advantages of coupled slab targets and of using a traveling wave geometry to drive targets with these short pulses. The main result of this work is combining the advantages of the double slab targets, the traveling wave geometry, and the multiple …

This paper describes the use of Fourier techniques to characterize the wavefront of optical components, specifically, the use of the power spectral density, (PSD), function. The PSDs of several precision optical components will be shown. Many of the optical components of interest to us have square, rectangular or irregularly shaped apertures with major dimensions up-to 800 mm. The wavefronts of components with non-circular apertures cannot be analyzed with Zernicke polynomials since these functions are an orthogonal set for circular apertures only. Furthermore, Zernicke analysis is limited to treating low frequency wavefront aberrations; mid-spatial scale and high frequency error are expressed only as ``residuals.`` A more complete and powerful representation of the optical wavefront can be obtained by Fourier analysis in 1 or 2 dimensions. The PSD is obtained from the amplitude of frequency components present in the Fourier spectrum. The PSD corresponds to the scattered intensity as a function of scattering angle in the wavefront and can be used to describe the intensity distribution at focus. The shape of a resultant wavefront or the focal spot of a complex multi-component laser system can be calculated and optimized using the PSDs of individual optical components which comprise it.