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CEBAF is a 4 GeV, 200 {micro}A five-pass recirculating superconducting electron accelerator that has been operating for nuclear physics research at full energy since November 95. The beam current has been increased to over 180 {micro}A at 4 GeV with the maximum current in the linac over 900 {micro}A. The superconducting cavities operate in a regime where the beam-induced voltage is comparable to the accelerating gradient. The operational limits and the issues required to maintain stable operation of the 1,497 MHz superconducting cavities will be discussed, together with the implications for the other accelerator systems. There are three experimental Halls which can run simultaneously with three interleaved 499 MHz bunch trains and RF separators. Operation with simultaneous beams to two Halls is now routine, and simultaneous three beam operation has been demonstrated. The maximum design current per bunch train (120 {micro}A) has been achieved. Hall B eventually requires beam currents as low as 1 nA (200 pA has been delivered) simultaneous with delivery of up to 200 {micro}A to the other Halls. The required beam current ratio of 10,000 has been achieved; development of 1 nA beam position monitors continues.

RF and magnet system configuration and monitoring tools are being implemented at Jefferson Lab to improve system reliability and reduce operating costs. They are prototype components of the Momentum Management System being developed. The RF is of special interest because it affects the momentum and momentum spread of the beam, and because of the immediate financial benefit of managing the klystron DC supply power. The authors describe present and planned monitoring of accelerating system parameters, use of these data, RF system performance calculations, and procedures for magnet configuration for handling beam of any of five beam energies to any of three targets.

Films with layers of Nb, Cu, and Sn have been fabricated to simulate a Nb{sub 3}Sn bronze-type process. These Nb{sub 3}Sn films have produced critical current densities greater than 1 x 10{sup 6} A/cm{sup 2} at 4.2 K and 7.5 T. Niobium films doped with Y, Sc, Dy, Al{sub 2}O{sub 3}, and Ti have been deposited with e-beam co-evaporation onto 75 mm diameter Si wafers with a 100 nm SiO{sub 2} buffer layer. The Nb layer was followed by a layer of Cu and a layer of Sn to complete the bronze-type process. The films with the highest J{sub c} had about 8 vol. % Sc and about 18 vol. % Al{sub 2}O{sub 3}. Characterization of the microstructure by TEM shows that these high J{sub c} films contained high density of inclusions about 5 nm in size and that the grain size of the Nb{sub 3}Sn is about 20-25 nm for samples heat treated at 700 C for up to eight hours.

Some recent developments in the weakly-coupled heterotic string phenomenology are reviewed. We discuss several important issues such as dilaton/moduli stabilization, supersymmetry breaking (by hidden-sector gaugino condensation), gauge coupling unification (or the Newton's constant), the QCD axion, as well as cosmological problems involving the dilaton/moduli and the axion.

In the rush to explore the B system, one should not ignore the potential of rare K decays. The charged and neutral FCNC K {yields} {pi}{nu}{bar {mu}} decays are theoretically very clean, on a par with B {yields} {psi}K{sub S}, which measures {beta}, and much less problematic than B {yields} {pi}{pi} and B{sub s} {yields} K{sup +}K{sup -} or B{sub s} {yields} K*{sup +}K*{sup -} which have been proposed to measure {alpha} and {gamma} respectively. B(K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}), which in the Standard Model yields information on |V*{sub ts}V{sub td}|, is closely related to the ratio of B{sub d} - {bar B}{sub d} to B{sub s}-{bar B}{sub s}, mixing, which yields |V{sub td}/V{sub ts}|. It is essential to compare such clean measurements from the B and K sectors, because new physics is likely to manifest itself in apparent disagreements[12]. Measuring the branching ratios of K {yields} {pi}{nu}{bar {nu}} decays is a challenge, but the current proven reach in sensitivity for the charged mode and the prospect of measuring the neutral mode at AGS-2000 indicate that this window into flavor physics is on the verge of becoming an exploitable reality.

This paper describes the design and fabrication of a vacuum pumping system for the ATP/LEDA (Low Energy Demonstration Accelerator) RFQ (Radio Frequency Quadrupole) linac. Resulted from the lost proton beam, gas streaming from the LEBT (Low Energy Beam Transport) and out-gassing from the surfaces of the RFQ cavity and vacuum plumbing, the total gas load will be on the order of 7.2 x 10{sup -4} Torr-liters/sec, consisting mainly of hydrogen. The system is designed to pump on a continual basis with redundancy to ensure that the minimal operating vacuum level of 1 x 10{sup -6} Torr is maintained even under abnormal conditions. Details of the design, performance analysis and the preliminary test results of the cryogenic pumps are presented.

Prior to the current project, development of the DSRP was done in a laboratory setting, using synthetic gas mixtures to simulate the regeneration off-gas and coal gas feeds. The objective of the current work is to further the development of zinc titanate fluidized-bed desulfurization (ZTFBD) and the DSRP for hot-gas cleanup by testing with actual coal gas. The objectives of this project are to: (1) Develop and test an integrated, skid-mounted, bench-scale ZTFBD/DSRP reactor system with a slipstream of actual coal gas; (2) Test the bench-scale DSRP over an extended period with a slipstream of actual coal gas to quantify the degradation in performance, if any, caused by the trace contaminants present in coal gas (including heavy metals, chlorides, fluorides, and ammonia); (3) Expose the DSRP catalyst to actual coal gas for extended periods and then test its activity in a laboratory reactor to quantify the degradation in performance, if any, caused by static exposure to the trace contaminants in coal gas; (4) Design and fabricate a six-fold larger-scale DSRP reactor system for future slipstream testing; (5) Further develop the fluidized-bed DSRP to handle high concentrations (up to 14 percent) of SO{sub 2} that are likely to be encountered when …

The overall objective of this project was to learn more about controlling emissions of hazardous air pollutants (HAPs) from coal-fired power plants that are equipped with wet flue gas desulfurization (FGD) systems. The project was included by FETC as a Phase I project in its Mega-PRDA program. Phase I of this project focused on three research areas. These areas in order of priority were: (1) Catalytic oxidation of vapor-phase elemental mercury; (2) Enhanced particulate-phase HAPs removal by electrostatic charging of liquid droplets; and (3) Enhanced mercury removal by addition of additives to FGD process liquor. Mercury can exist in two forms in utility flue gas--as elemental mercury and as oxidized mercury (predominant form believed to be HgCl{sub 2}). Previous test results have shown that wet scrubbers effectively remove the oxidized mercury from the gas but are ineffective in removing elemental mercury. Recent improvements in mercury speciation techniques confirm this finding. Catalytic oxidation of vapor-phase elemental mercury is of interest in cases where a wet scrubber exists or is planned for SO{sub 2} control. If a low-cost process could be developed to oxidize all of the elemental mercury in the flue gas, then the maximum achievable mercury removal across the existing …

The objective of this project to develop an advanced flue gas desulfurization (FGD) process that has decreased capital and operating costs, higher SO{sub 2} removal efficiency, and better by-product solids quality than existing, commercially available technology. A clear liquor process (which uses a scrubbing liquid with no solids) will be used to accomplish this objective rather than a slurry liquor process (which contains solids). This clear liquor scrubbing (CLS) project is focused on three research areas: (1) Development of a clear liquor scrubbing process that uses a clear solution to remove SO{sub 2} from flue gas and can be operated under inhibited-oxidation conditions; (2) Development of an anhydrite process that converts precipitated calcium sulfite to anhydrous calcium sulfate (anhydrite); and (3) Development of an alkali/humidification process to remove HCl from flue gas upstream of the FGD system. The anhydrite process also can be retrofit into existing FGD systems to produce a valuable by-product as an alternative to gypsum. This fits well into another of FETC's PRDA objectives of developing an advanced byproduct recovery subsystem capable of transforming SO{sub 2} into a useable byproduct or high-volume valuable commodities of interest. This paper describes the proposed processes, outlines the test approach, and …

This study aims at the development of an effective nondestructive evaluation technique to predict the remaining useful life of a ceramic candle filter during a power plant's annual maintenance shutdown. The objective of the present on-going study is to establish the vibration signatures of ceramic candle filters at varying degradation levels due to different operating hours, and to study the various factors involving the establishment of the signatures.

Experimental and theoretical evidence for the nonequilibrium Zeldovich-von Neumann-Doring (NEZND) theory of self-sustaining detonation is presented. High density, high temperature transition state theory is used to calculate unimolecular reaction rate constants for the initial decomposition of gaseous norbornene, liquid nitromethane, and solid, single crystal pentaerythritol tetranitrate as functions of shock temperature. The calculated rate constants are compared to those derived from experimental induction time measurements at various shock and detonation states. Uncertainties in the calculated shock and von Neumann spike temperatures are the main drawbacks to calculating these reaction rates. Nanosecond measurements of the shock temperatures of unreacted explosives are necessary to reduce these uncertainties.

Heat flow in a cylinder with internal heating is used as a basis for deriving a simple theory of detonation front curvature, leading to the prediction of quadratic curve shapes. A thermal conductivity of 50 MW/mm{sup 2} is found for TATB samples.

The objective of this study is to develop a second generation HGD process that regenerates the sulfided sorbent directly to elemental sulfur using SO{sub 2}, with minimal consumption of coal gas. The goal is to have better overall economics than DSRP when integrated with the overall IGCC system.

The electrostatic comb finger drive has become an integral design for microsensor and microactuator applications. This paper reports on utilizing the levitation effect of comb fingers to design vertical-to-the-substrate actuation for interferometric applications. For typical polysilicon comb drives with 2 {micro}m gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 {micro}m above the stationary comb fingers. This distance is ideal for many phase shifting interferometric applications. Theoretical calculations of the vertical actuation characteristics are compared with the experimental results, and a general design guideline is derived from these results. The suspension flexure stiffnesses, gravity forces, squeeze film damping, and comb finger thicknesses are parameters investigated which affect the displacement curve of the vertical microactuator. By designing a parallel plate capacitor between the suspended mass and the substrate, in situ position sensing can be used to control the vertical movement, providing a total feedback-controlled system. Fundamentals of various capacitive position sensing techniques are discussed. Experimental verification is carried out by a Zygo distance measurement interferometer.

Commensurability effects between the superconducting flux line lattice and a square lattice (period d=1{micro}m and diameter D=0.4{micro}m) of submicron holes in 1500 {angstrom} vanadium films were studied by atomic force microscopy, DC magnetization, AC susceptibility, magnetoresistivity and I-V measurements. Peaks in the magnetization and critical current at matching fields are found to depend nonlinearly upon the value of external AC field or current, as well as the inferred symmetry of the flux line lattice.

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Low-activity products will be in the form of soldified waste and optional matrix and filler materials enclosed in sealed metal boxes. Acceptance specifications limit the physical characteristics of the containers, the chemical and physical characteristics of the waste form and other materials that may be in the container, the waste loading, and the radionuclide leaching characteristics of the waste form. The specifications are designed to ensure that low-activity waste products will be compatible with the driving regulatory and operational requirements and with existing production technologies.

The authors conducted Product Consistency Tests (PCTs) with a surrogate low-activity waste (LAW) glass to (1) evaluate the possible use of various test conditions in a specification test for LAW waste forms, (2) measure the reproducibility of the test at low temperatures, and (3) determine if the rates calculated from 7-day PCTs bound the rates measured in PCT conducted for longer durations, which represent more advanced corrosion. The effects of temperature and pH on the dissolution rate in PCTs are much less than the effects observed in dilute solutions due to the buildup of dissolved glass components in the PCTs. The precision of replicate 7-day tests at 20 and 40{degrees}C was limited by the analytical uncertainty. The dissolution rates at all temperatures decreased with the test duration initially. However, the dissolution rates in tests at 70 and 90{degrees}C increased when certain alteration phases formed after about 100 and 500 days, respectively; the rates in some tests exceeded that measured in a 7-day PCT. While the 7-day PCT does not provide a bounding rate for this glass at 70 or 90{degrees}C, tests for longer durations are needed to determine if a 7-day test provides a bounding rate at lower temperatures.

The short- and intermediate-range order as well as atomic dynamics in various phosphate glasses were investigated using neutron diffraction and inelastic scattering. The 3-D network of corner-sharing PO{sub 4} tetrahedra in g-P{sub 2}O{sub 5} is highly unstable and hygroscopic. Depolymerization of the network to chain-like structure and eventually to unconnected PO{sub 4} units by incorporating alkali, alkali-earth or transition-metal modifiers is clearly evident in the structure factor S(Q) in the Q < 4 {angstrom}{sup -1} region. The dynamic response to such structural changes is equally strong: e.g., the broad P-O stretching band extending to 170 meV in g-P{sub 2}O{sub 5} is sharpened and shifted down to {approximately}125 meV in the orthophosphate composition. The correlation between the microscopic structure and physical properties for a series of P-glasses is discussed.

The application of propagation of variance (POV) for estimating the variance of a material balance is straightforward but tedious. Several computer codes exist today to help perform POV. Examples include MAWST (`materials accounting with sequential testing,` used by some Department of Energy sites) and VP (`variance propagation,` used for training). Also, some sites have such simple error models that custom `spreadsheet like` calculations are adequate. Any software to perform POV will have its strengths and weaknesses. A main disadvantage of MAWST is probably its limited form of error models. This limited form forces the user to use cryptic pseudo measurements to effectively extend the allowed error models. A common example is to include sampling error in the total random error by dividing the actual measurement into two pseudo measurements. Because POV can be tedious and input files can be presented in multiple ways to MAWST, it is valuable to have an alternative method to compare results. This paper describes a new code, VPSim, that uses Monte Carlo simulation to do POV. VPSim does not need to rely on pseudo measurements. It is written in C++, runs under Windows NT, and has a user friendly interface. VPSim has been tested on …

Article on the quantitative determination of Cr(III) and Co(II) using a spectroscopic H-point standard addition method.

The International Workshop on Sustainable Forest Management: Monitoring and Verification of Greenhouse Gases was held in San Jose, Costa Rica, July 29-31, 1996. The main objectives of the workshop were to: (1) assemble key practitioners of forestry greenhouse gas (GHG) or carbon offset projects, remote sensing of land cover change, guidelines development, and the forest products certification movement, to offer presentations and small group discussions on findings relevant to the crucial need for the development of guidelines for monitoring and verifying offset projects, and (2) disseminate the findings to interested carbon offset project developers and forestry and climate change policy makers, who need guidance and consistency of methods to reduce project transaction costs and increase probable reliability of carbon benefits, at appropriate venues. The workshop brought together about 45 participants from developed, developing, and transition countries. The participants included researchers, government officials, project developers, and staff from regional and international agencies. Each shared his or her perspectives based on experience in the development and use of methods for monitoring and verifying carbon flows from forest areas and projects. A shared sense among the participants was that methods for monitoring forestry projects are well established, and the techniques are known and …

As part of a project to develop methods of placing highly reflective multilayer coatings on the inside of Wolter I mirrors, we have been pursuing a program of measuring flat mirrors. These flats have been produced and examined at various stages of the process we plan to use to fabricate multilayer coated Wolter I mirrors. The flats were measured via optical profiler, AFM, (both done at Brookhaven National Lab) and X-ray reflection (done at the Argonne National Lab (ANL) Advanced Photon Source (APS)). We report for the first time, to our knowledge, the successful placement of multilayers on an electroform by depositing the multilayers on a master and then electroforming onto this master and removing the multilayers, intact, on the electroform. This process is the one we plan to use to place multilayers on the inside of Wolter I optics.