Three potential methods for measuring the surface tritium content of the TFTR vacuum vessel are described, each based on a different technique for measuring the in situ beta emission from tritium. These methods should be able to provide both a local and a global assessment of the tritium content within the top [approx] 1[mu]m of the inner wall surface.

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A search for cosmological supernovae has discovered a number of a type la supernovae. In particular, one at z = 0.458 is the most distant supernova yet observed. There is strong evidence from measurements of nearby type Ia supernovae that they can be considered as 'standard candles'. We plan to use these supernovae to measure the deceleration in the general expansion of the universe. The aim of our experiment is to try and observe and measure about 30 such distant supernovae in order to obtain a measurement of the deceleration parameter q{sub 0} which is related to {Omega}. Here {Omega} is the ratio of the density of the universe to the critical density, and we expect a measurement with an accuracy of about 30%.

Wind affects the radon-222 entry rate from soil into buildings and the resulting indoor concentrations. To investigate this phenomenon, we employ a previously tested three-dimensional numerical model of soil-gas Bow around houses, a commercial computational fluid dynamics code, an established model for determining ventilation rates in the presence of wind, and new wind tunnel results for the ground-surface pressure field caused by wind. These tools and data, applied under steady-state conditions to a prototypical residential building, allow us (1) to determine the complex soil-gas flow patterns that result from the presence of wind-generated ground-surface pressures, (2) to evaluate the effect of these flows on the radon concentration in the soil, and (3) to calculate the effect of wind on the radon entry rate and indoor concentration. For a broad range of soil permeabilities, two wind speeds, and two wind directions, we quantify the"flushing" effect of wind on the radon in the soil surrounding a house, and the consequent sharp decrease in radon entry rates. Experimental measurements of the time-dependent radon concentration in soil gas beneath houses confirm the existence of wind-induced flushing. Comparisons are made to modeling predictions obtained while ignoring the effect of the wind-generated ground-surface pressures. These investigations …

Molecular dynamics is employed to study the low energy states of a beam of charged particles subject to circumferentially varying guiding and focusing forces and with Coulomb forces between the particles. In a constant gradient ring, the lowest energy state is never ordered, but in an alternating gradient structure, operating below the transition energy, the lowest state is ordered. The nature and characteristics of the ground state depends upon the beam density and the ring parameters. For zero temperature the crystal remains intact for a very long time, but at nonzero temperatures it gains energy from the lattice. A critical temperature exists above which the crystal melts rapidly.

It is shown, theoretically, that a coupling cavity; namely an rf cavity operating in the TM{sup 210} mode, when inserted in a storage ring will enhance the coupling between longitudinal and transverse degrees of freedom. As a result, it is shown that the demonstrated very effective laser cooling of the longitudinal motion, can now be extended to transverse motion; i.e., employed to cool a beam in all three directions.

There is a vast theoretical and experimental support for idea that op quark as a weak isospin partner to b-quark should exist. Production cross section is steeply falling function of top quark mass. Therefore realistically at present only Tevatron p[anti p] collider at FNAL, with total energy 1.8 TeV in CMS system, still has a chance of top quark discovery. Dominant production mechanism for top quarks at Tevatron is pair production of t[anti t]. With almost 100% probability t ([anti t]) decays in mode t [yields] W[sup +]b. Distinct features of this decay provide very good signatures of top quark production which helps to reduce otherwise very high level of background. Based on simple combinatorial arguments one can show that W should decay in 1/9 cases into W [yields] l + [nu] where l stands for lepton (e,[mu],[tau]). Very clean signature represents case when both W's from t and [anti t] decay into e ([mu]) + [nu]. In this case experimental observation will be two isolated leptons characterized by large transverse momentum, large missing transverse energy E[sub T] and 2 b quark jets. Jets originated from b quarks can be quite frequently recognized by presence of secondary vertices associated with …

High in the northcentral mountains of Los Alamos, New Mexico, is the Manuel Lujan Jr. Neutron Scattering Center (LANSCE), a pulsed-spallation neutron source located at Los Alamos National Laboratory. At LANSCE, neutrons are produced by spallation when a pulsed 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by a linear accelerator and an associated Proton Storage Ring (PSR), which alters the intensity, time structure, and repetition rate of the pulses. In October 1986, LANSCE was designated a national user facility, with a formal user program initiated in 1988. In July 1989, the LANSCE facility was dedicated as the Manuel Lujan Jr. Neutron Scattering Center in honor of the long-term Congressman from New Mexico. At present, the PSR operates with a proton pulse width of 0.27 [mu]s at 20 Hz and 80 [mu]A, attaining the highest peak neutron flux in the world and close to its goal of 100 [mu]A, which would yield a peak thermal neutron flux of 10[sup 16] n/cm[sup [minus]2]s[sup [minus]1]. This paper discusses the target/moderator/reflector shield system, the LANSCE instruments, the facility improvement projects, and user programs.

Los Alamos and Grumman are cooperatively investigating a debris free source for EUV lithography. This source utilizes the predicted anomalous energy loss of a short pulse electron beam in a preformed plasma to heat and ionize the ions to a charge state where efficient radiation at 130[angstrom] occurs. Accelerators developed for the free electron laser program at Los Alamos are used as the electron bunch source. These accelerators use a laser driven photocathode to produce 15 psec electron bunches containing 4 nC of charge with an energy of 15.5 MeV. These micropulses are produced at a repetition rate of 108 MHz and continue for the length of the rf macropulse energizing the accelerator cavities, typically 1--10 [mu]sec. The weakly ionized preformed plasma is created by purely classical collisional ionization caused by the initial few electron micropulses within the macropulse. When a critical electron density is reached, n[sub e] [approx equal] 1.6 [times] 10[sup 15]/[tau][sup 2] cm[sup [minus]3], where [tau] is the FWHM, in psec, of the electron bunch, the plasma responds collectively to the electron micropulse generating a large amplitude plasma wave. The plasma wave efficiently slows the high energy electron beam while heating the background plasma electrons. The initial …

We have designed a flow tube reactor for supercritical water oxidation of wastes that confines the oxidation reaction to the vicinity of the axis of the tube. This prevents high temperatures and reactants as well as reaction products from coming in intimate contact with reactor walls. This implies a lessening of corrosion of the walls of the reactor. We display numerical simulations for a vertical reactor with conservative design parameters that illustrate our concept. We performed our calculations for the destruction of sodium nitrate by ammonium hydroxide In the presence of supercritical water, where the production of sodium hydroxide causes corrosion. We have compared these results with that for a horizontal set-up where the sodium hydroxide created during the reaction ends up on the floor of the tube, implying a higher probability of corrosion.

Semiempirical and ab initio Hartree Fock computational results indicate that the highly reactive dienophile tetramethyldisilene, Me{sub 2}Si=SiMe{sub 2}, is an excellent candidate for a novel functionalization of the equator of C{sub 70} via a [2+4] cycloaddition to the 21, 22, 23, 42 carbons. Thermal or photochemical generation of tetramethyldisilene in the presence of C{sub 70} results in similar complex mixtures in which the major product appears to be that of [2+2] cycloaddition to the 7,8 carbons of C{sub 70}. A minor product clearly results from [2+2] cycloaddition to the 1,9 carbons. Both of these products are hydrolytically unstable and are converted nonspecifically to mixtures of 1,9- and 7,8-C{sub 70}H{sub 2} which are also present in HPLC traces of the reaction mixtures.

This paper presents work to develop benchmarked theoretical models of scrape-off-layer (SOL) characteristics in diverted tokamaks by comparing shot simulations using the UEDGE plasma fluid and DEGAS neutral transport codes to measurements of the DIII-D SOL plasma. The experimental data include the radial profiles of n{sub e} T{sub e}, and T{sub i}, the divertor exhaust power, the intensity of H{sub {alpha}} emission, and profiles of the radiated power. A very simple model of the anomalous perpendicular transport rates produces consistency between the calculated and measured radial profiles of the divertor power, and of the midplane densities and temperatures. Experimentally, the measured exhaust power is now 80--90% of the input power. The simulated peak power on the outer leg of the divertor floor is now within 20% of the measured power. Various sensitivities of these comparisons to model assumptions are described. Finally, these benchmarked models have been used to examine the effects of various baffle configurations for the Radiative Divertor Upgrade in DIII-D.

The authors have measured the strong coupling {alpha}{sub s} using hadronic decays of Z{sup 0} bosons collected by the SLD experiment at SLAC. The data were compared with QCD predictions both at fixed order, O({alpha}{sub s}{sup 2}), and including resummed analytic formulae based on the leading and next-to-leading logarithm approximation. The study includes event shapes, jet rates, and particle correlations. They checked the consistency between {alpha}{sub s} extracted from these different measures and found the dominant uncertainty on {alpha}{sub s} to be from uncalculated higher order contributions.

This experiment was designed for high school students who have a very limited background in ceramic materials, but the experiments could also be used at the college level. The objective of the experiment is to teach students about the development of mechanical strength in a ceramic material as a result of the firing process and about testing methods used for brittle materials. In the experiment, clay-based ceramic bars of uniform circular cross section are prepared by extrusion. The bars are then fired at temperatures high enough to achieve high strength by development of a glassy bonding phase. Finally, the bars will be stressed to failure in a simple testing machine. This will quantify the increase in strength as a function of firing temperature.

The purpose of this paper is to provide an update on what we`ve accomplished and have planned in our plating operation at Lawrence Livermore National Laboratory (LLNL) in the area of waste minimization. Our efforts have included issues other than waste minimization and, therefore, fall under the wider umbrella entitled pollution prevention or environmentally conscious electroplating. Approximately one year has passed since our last report on pollution prevention and since this topic remains a high-effort activity much more has been accomplished. Our efforts to date fall under the first two generation categories of waste reduction. Good housekeeping practices, inventory control, and minor changes in operating practices (first generation) resulted in an impressive amount of waste reduction. In the second generation of waste reduction, current technology, separation technologies, and material substitutions were used to reduce emission and wastes. The third generation of improvements requires significant technological advances in process synthesis and engineering. We are presently starting some projects in this third generation phase and these will be discussed at the end of this paper.

In DIII-D the authors have investigated the long pulse evolution of high poloidal beta ({sub beta}{sub p}), double-null diverted H-mode discharges, which exhibit high bootstrap current fractions attractive for a reactor. At low currents I{sub p}, the current profile evolved over several seconds and the on-axis safety factor (q{sub 0}) increased. When q{sub 0} increased above {approximately}2, the MHD character changed from an m/n = 2/1 to an m/n = 3/1 internal kink mode, where m(n) are poloidal (toroidal) mode numbers, which then disappeared with further increases in q{sub 0}. Coincident with a strong reduction of fluctuations, the authors observed enhanced core confinement, leading to strong density peaking, a further rise in {beta}{sub p}, and a bootstrap current increasing to I{sub boot}/I{sub p} {approx} 0.8, peaked within the core. Ideal MHD calculations showed access to second stability during the density rise. During the enhanced performance phase core particle lifetime ({tau}{sub p}) and global energy lifetime ({tau}{sub E}) increased by factors of 2 and 1.2 respectively. Transport analysis showed that core particle and thermal diffusivities D{sub e} and {chi}{sub eff} approached neoclassical values. During the low current experiments, large losses of fast ions (typically {approximately}50% at 0.4 MA) were observed; at …

The late stages of char combustion have a special technological significance, as carbon conversions of 99% or greater are typically required for the economic operation of pulverized coal fired boilers. In the present article, two independent optical techniques are used to investigate near-extinction and final burnout phenomenas. Captive particle image sequences, combined with in situ optical measurements on entrained particles, provide dramatic illustration of the asymptotic nature of the char burnout process. Single particle combustion to complete burnout is seen to comprise two distinct stages: (1) a rapid high-temperature combustion stage, consuming about 70% of the char carbon and ending with near-extinction of the heterogeneous reactions due to a loss of global particle reactivity, and (2) a final burnout stage occurring slowly at lower temperatures. For particles containing mineral matter, the second stage can be further subdivided into: (2a) late char combustion, which begins after the near-extinction event, and converts carbon-rich particles to mixed particle types at a lower temperature and a slower rate; and (2b) decarburization of ash -- the removal of residual carbon inclusions from inorganic (ash) frameworks in the very late stages of combustion. This latter process can be extremely slow, requiring over an order of magnitude …

We report on preliminary measurements of the inclusive single muon and dimuon cross sections in p{bar p} collisions at {radical}s = 1.8 TeV using the D0 detector at the Fermilab collider. From these results, we extract the cross section for b-quark production for the kinematic range {vert_bar}yb{vert_bar} < 1.0 and 6 < p{sub t}{sup b} < 50 GeV/c. We also report measurements on the J/{psi} production, and correlations between muons in dimuon events.

Historically, pollution prevention activities within the Department of Energy (DOE) have focused on existing process waste streams. However, the DOE estimates that 70 percent of the opportunity to reduce or eliminate pollutants is gained or lost during design. Design is considered a critical component of the DOE`s operations, products and services, as evidenced by the numerous new facilities planned to support the cleanup mission of the complex. Pollution prevention during design: (a) significantly reduces the potential generation of waste and environmental releases, (b) promotes the use of energy efficient materials, (c) minimizes resource consumption, and (d) lowers life-cycle costs. Life-cycle cost considerations during design can include construction, operation, and eventual decommissioning of the facility. This paper highlights: (1) the development of the guideline, including specific examples of the guideline`s content and intended use, (2) a discussion on the philosophy and content of the training module, (3) a strategy for integrating the guideline`s use into the existing DOE design process, and (4) future plans for enhancing the guideline and training class while continuing to integrate pollution prevention into the DOE design process.

Radiation-induced segregation (RIS) to grain boundaries in Fe-Ni-Cr-Si stainless alloys has been measured as a function of irradiation temperature and dose. Heavy-ion irradiation was used to produce damage levels from 1 to 20 displacements per atom (dpa) at temperatures from 175 to 550{degrees}C. Measured Fe, Ni, and Cr segregation increased sharply with irradiation dose (from G to 5 dpa) and temperature (from 175 to about 350{degrees}C). However, grain boundary concentrations did not change significantly as dose or temperatures were further increased. Although interfacial compositions were similar, the width of radiation-induced enrichment or depletion profiles increased consistently with increasing dose or temperature. Impurity segregation (Si and P) was also measured, but only Si enrichment appeared to be radiation-induced. Grain boundary Si peaked at levels approaching 10 at% after irradiation doses to 10 dpa at an intermediate temperature of 325{degrees}C. No evidence of grain boundary silicide precipitation was detected after irradiation at any temperature. Equilibrium segregation of P was measured in the high-P alloys, but interfacial concentration did not increase with irradiation exposure. Comparisons to reported RIS in neutron-irradiated stainless steels revealed similar grain boundary compositional changes for both major alloying and impurity elements.

Searches have been made for first generation scalar and vector leptoquarks by the D0 collaboration and for second generation scalar leptoquarks by the CDF collaboration. The data sample is from the 1992-93 p{bar p} run at {radical}s = 1.8 TeV at the Fermilab Tevatron Collider. Assuming that leptoquarks are pair produced and decay into charged leptons and quarks with branching fraction {beta}, mass limits at the 95% Confidence Level (CL) have been obtained. For first generation scalar leptoquarks the lower mass limit is 130 GeV/c{sup 2} for {beta} = 1.0 and 116 GeV/c{sup 2} for {beta} = 0.5. For first generation vector leptoquarks with {kappa}, the anomalous coupling, of 1.0 and {beta} = 1.0, the lower mass limit is 240 GeV/c{sup 2} and for {kappa} = 1.0, {beta} = 0.5, the lower mass limit is 240 GeV/c{sup 2}. For {kappa} = 0 and {beta} = 1.0, the lower mass limits is 190 GeV/c{sup 2} and for {kappa} = 0, {beta} = 0.5, the lower mass limit is 185 GeV/c{sup 2}. For second generation scalar leptoquarks, the mass limits are 133 GeV/c{sup 2} for {beta} = 1.0 and 98 GeV/c{sup 2} for {beta} = 0.5. A search for squarks and gluinos, …

Certain radioactive waste storage tanks at the United States Department of Energy Hanford facilities continuously generate gases as a result of radiolysis and chemical reactions. The congealed sludge in these tanks traps the gases and causes the level of the waste within the tanks to rise. The waste level continues to rise until the sludge becomes buoyant and ``rolls over``, changing places with heavier fluid on top. During a rollover, the trapped gases are released, resulting, in a sudden drop in the waste level. This is known as a gas release event (GRE). After a GRE, the wastes leading to another GRE. We present nonlinear time waste re-congeals and gas again accumulates leading to another GRE. We present nonlinear time series models that produce simulated sample paths that closely resemble the temporal history of waste levels in these tanks. The models also imitate the random GRE, behavior observed in the temporal waste level history of a storage tank. We are interested in using the structure of these models to understand the probabilistic behavior of the random variable ``time between consecutive GRE`s``. Understanding the stochastic nature of this random variable is important because the hydrogen and nitrous oxide gases released from …

The high cost of optoelectronic (OE) devices is due mainly to the labor-intensive packaging process. Manually pigtailing such devices as single-mode laser diodes and modulators is very time consuming with poor quality control. The Photonics Program and the Engineering Research Division at LLNL are addressing several issues associated with automatically packaging OE devices. A furry automated system must include high-precision fiber alignment, fiber attachment techniques, in-situ quality control, and parts handling and feeding. This paper will present on-going work at LLNL in the areas of automated fiber alignment and fiber attachment. For the fiber alignment, we are building an automated fiber pigtailing machine (AFPM) which combines computer vision and object recognition algorithms with active feedback to perform sub-micron alignments of single-mode fibers to modulators and laser diodes. We expect to perform sub-micron alignments in less than five minutes with this technology. For fiber attachment, we are building various geometries of silicon microbenches which include on-board heaters to solder metal-coated fibers and other components in place; these designs are completely compatible with an automated process of OE packaging. We have manually attached a laser diode, a thermistor, and a thermo-electric heater to one of our microbenches in less than 15 minutes …

The central limit theorem can be applied to a Monte Carlo solution if: The random variable x has a finite mean and a finite variance; and the number N of independent observations grows large. When these two conditions are satisfied, a confidence interval based on the normal distribution with a specified coverage probability can be formed. The first requirement is generally satisfied by the knowledge of the type of Monte Carlo tally being used. The Monte Carlo practitioner has only a limited number of marginally quantifiable methods to assess the fulfillment of the second requirement. Ten new statistical checks have been created and added to MCNP4A to assist with this assessment. The checks examine the mean, relative error, figure of merit, and two new quantities: The relative variance of the variance; the empirical history score probability density function f(x). The two new quantities are described. For the first time, the underlying f(x) for Monte Carlo tallies is calculated for routine inspection and automated analysis. The ten statistical checks are defined, followed by the results from a statistical study on analytic Monte Carlo and other realistic f(x)s to validate their values and uses in MCNP. Passing all 10 checks is a …