The input from flavor-changing processes is reviewed and results of several analyses are presented on the top quark mass spectrum without recourse to the neutral-current data. A top quark mass in the range 135 {plus minus} 25 GeV is much preferred, but a very massive top quark above 300 GeV can not be ruled out. Comments are made about the future use of the inclusive decay B {yields} {gamma} + X{sub S=1} for constraining the top quark mass. 24 refs., 2 figs.

Irradiation experiments were conducted on multilayer (ML) and coevaporated (CO) thin films in order to examine the role that the heat of mixing ({Delta}H{sub mix}) has in ion-induced grain growth. Room temperature irradiations using 1.7 MeV Xe were performed in the High Voltage Electron Microscope at Argonne National Laboratory. The alloys studied (Pt-Ti, Pt-V, Pt-Ni, Au-Co and Ni-Al) spanned a large range of {Delta}H{sub mix} values. Comparison of grain growth rates between ML and CO films of a given alloy confirmed a heat of mixing effect. Differences in grain growth rates between ML and CO films scaled according to the sign and magnitude of {Delta}H{sub mix} of the system (with exception of the Pt-V system). Substantial variations in growth rates among CO alloy films experiencing similar irradiation damage demonstrated that a purely collisional approach is inadequate for describing ion-induced grain growth and consideration must also be given to material-specific properties. Results from CO alloy films were consistent with a thermal spike model of ion-induced grain growth. The grain boundary mobility was observed to be proportional to the thermal spike-related parameter, (F{sub D}{sup 2})/({Delta}H{sub coh}{sup 3}), where F{sub D} is the deposited damage energy and {Delta}H{sub coh} is the cohesive energy.

The Advanced Divertor (AD) for General Atomics tokamak, DIII-D, was installed in the summer of 1990. The AD has enabled two classes of physics experiments to be run: divertor biasing and divertor baffling. Both are new experiments for DIII-D. The AD has two principal components: (1) a continuous ring electrode; and (2) a toroidally symmetric baffle. The tokamak can be run in bias baffle or standard DIII-D divertor modes by accurate positioning of the outer divertor strike point through the use of the DIII-D control system. The paper covers design, analysis, fabrication, installation, instrumentation, testing, initial operation, and future plans for the Advanced Divertor from an engineering viewpoint. 2 refs., 5 figs.

This presentation is a review of recent measurements on charm production at fixed-target experiments. The measurements are relevant to a number of basic physics issues: tests of perturbative QCD, fragmentation, and basic hadronic structure. We now have high quality, high statistics data from several fixed-target experiments. These include a total of about 30,000 fully reconstructed open charm decays and even more copious J/{Psi}, {Psi}, and {Upsilon} decays. Reconstruction of the full data is now reaching completion and we await final results for systematic physics interpretations. This review of the current situation will be followed by a brief look beyond, toward beauty production at fixed-target experiments.

Differential-algebraic boundary value problems arise in the modelling of singular optimal control problems and in parameter estimation for singular systems. A new class of numerical methods for these problems is introduced, and shown to overcome difficulties with previously defined numerical methods. 4 refs., 1 tab.

Differential-algebraic equation (DAE) boundary value problems arise in a variety of applications, including optimal control and parameter estimation for constrained systems. In this paper we survey these applications and explore some of the difficulties associated with solving the resulting DAE systems. For finite difference methods, the need to maintain stability in the differential part of the system often necessitates the use of methods based on symmetric discretizations. However, these methods can suffer from instability and loss of accuracy when applied to certain DAE systems. We describe a new class of methods, Projected Implicit Runge-Kutta Methods, which overcomes these difficulties. We give convergence and stability results, and present numerical experiments which illustrate the effectiveness of the new methods. 20 refs., 1 tab.

The RF control system for the CEBAF accelerator uses calibration tables to calibrate and linearize critical components in the RF control modules. This includes compensation for temperature drifts. Calibration data are stored in nonvolatile RAM on the CPU board in the control module. Algorithms for calibration of components like the vector modulator for the phase reference and the gradient detector are described. The calibration will be performed in a dedicated test stand which will be completely automated. The microprocessor in the control modules allows running of complex algorithms to achieve phase lock and optimize system gains for minimum residual errors for different gradients and beam loading.

Activation analysis has been made for the US ITER design. The radioactivity and the decay heat have been calculated, during operation and after shutdown for the two ITER phases, the Physics Phase and the Technology Phase. The Physics Phase operates about 24 full power days (FPDs) at fusion power level of 1100 MW and the Technology Phase has 860 MW fusion power and operates for about 1360 FPDs. The point-wise gamma sources have been calculated everywhere in the reactor at several times after shutdown of the two phases and are then used to calculate the biological dose everywhere in the reactor. Activation calculations have been made also for ITER divertor. The results are presented for different continuous operation times and for only one pulse. The effect of the pulsed operation on the radioactivity is analyzed. 6 refs., 12 figs., 1 tab.

Stability of the YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) superconductor toward reacting with CO{sub 2} in CO{sub 2}/O{sub 2} gas mixtures during sintering was investigated as a function of the partial pressure of CO{sub 2} and temperature. The transport critical current density, J{sub c}, of the superconductor decreased drastically with increasing partial pressure of CO{sub 2} was increased, J{sub c} became zero (at 77 K) even though the major phase of the sample was still a superconductor as determined by magnetic susceptibility measurements. Microstructures and compositions of the samples were investigated by transmission electron microscopy in conjunction with energy-dispersive x-ray spectroscopy. Two types of grain boundaries were observed: {approximately}10% of the grain boundaries contained a second phase; the regions near the remaining grain boundaries were tetragonal. At high partial pressures of CO{sub 2}, the YBCO completely decomposed to BaCO{sub 3}, Y{sub 2}BaCuO{sub 5}, and CuO. 11 refs., 3 figs.

The CEBAF accelerator includes a linac section which accelerates multiple beams with different energies. Problems arise when performing orbit correction, due to the fact that correction of higher energy passes disturb lower energy trajectories. Therefore, a perfect orbit correction cannot be obtained for all energy beams at the same time.\nWe present methods and performance (using simulation results) for performing orbit corrections in such a system. Limitations to the correction methods are also addressed.\n

Dynamic growth of ash deposits was studied in a carefully controlled environment using high speed video cameras and temperature controlled deposition probes. Deposition data are reported as a function of coal type, extent of particle burnout,and time. Five coals varying in rank from bituminous to lignite were tested. The coals were tested at conditions simulating three locations in a boiler; the near-flame region, the superheater region, and the convection pass. Details of deposit formation were monitored for 90 minutes for each coal at each test condition. A particularly interesting result is that particle capture efficiencies, the fraction of flyash particles which adheres to the probe upon contact, have a strong time dependence, varying from near zero to near unity during deposit formation. Dependence of ash deposition on coal rank and location of the boiler is also discussed. 10 refs., 3 figs., 3 tabs.

The electron beam ion trap at Lawrence Livermore National Laboratory is used to produce and trap very highly charged ions for the study of electron-ion interactions. Measurements of x-ray transitions in neonlike thorium (Th{sup 80+}), ionization cross sections of lithiumlike barium (Ba{sup 53+}), and of level-specific dielectronic recombination cross sections of lithium iron (Fe{sup 23+}) are presented. 12 refs., 4 figs., 1 tab.

Ion optical design of the transfer line, which will be used to inject H{sup {minus}} beam at 600 MeV from the Coupled Cavity Linac (CCL) into the Low Energy Booster (LEB) synchrotron, is described. Space charge effects of up to 50 mA average beam current have been taken into account.

In August 1987, a routine Ames test on soot from the Lawrence Livermore National Laboratory (LLNL) 4-in. gun showed that the soot was mutagenic to Salmonella bacteria. Subsequent liquid chromatography on the soot showed that, out of hundreds of ultravoilet-absorbing compounds found in the residue, only three or four were mutagenic. When a sample large enough to weigh was collected, it was found that No environmentally identified complex mixture has ever been reported with as much Ames/Salmonella activity per gram as the gun residues.'' Since then, Ames tests of hundreds of samples have verified that the residues from our gun tanks may be hazardous to health. The actual degree of the hazard and the identity of the offending chemicals are still unknown. 2 refs.

A modular, multichannel current regulator system has been developed to power the low current correction and focusing magnets used for beam transport. The basic module consists of a relay rack housing four card crates with eight regulators per crate. The rack also contains a utility chassis and common power supplies. Each regulator card includes a communications microprocessor and a temperature controlled analog circuit block containing precision reference, serial DAC, shunt resistor and error amplifier. The regulators are linear, bipolar units capable of furnishing up to 10 amps at 20 volts with less than 0.01% ripple and drift.

As described in a previous article, the preinjector linac for SSRL's 3 GeV synchrotron is fed by a 2 MeV, 1.5 A, low-emittance microwave gun, consisting of a thermionic cathode mounted in the first cell of a 1-1/2-cell S-band cavity. In this article, we report on the successful operation of the low-emittance gun, the longitudinally-bunching alpha-magnet, and the three-microbunch FET-pulsed beam-chopper. Simulations predict a normalized rms emittance at the gun exit of less than 10 {pi}{center dot}m{sub e}c{center dot}{mu}m; chromatic effects in transport optics increase this to approximately 30 {pi}{center dot}m{sub e}c{center dot}{mu}m. The gun was specifically designed to have a longitudinal phase-space suited to magnetic compression, as a result of which we predict that peak currents in excess of 300 A in a 1 ps bunch are feasible with the existing alpha-magnet. Results of simulations and experiments will be presented and compared. 13 refs., 9 figs.

The biological effects of ionizing radiation exposure are the result of a complex sequence of physical, chemical, biochemical, and physiological interactions. One way to begin a search for an understanding of health effects of radiation is through the development of phenomenological models of the response. Many models have been presented and tested in the slowly evolving process of characterizing cellular response. A range of models covering different endpoints and phenomena has developed in parallel. Many of these models employ similar assumptions about some underlying processes while differing about the nature of others. An attempt is made to organize many of the models into groups with similar features and to compare the consequences of those features with the actual experimental observations. It is assumed that by showing that some assumptions are inconsistent with experimental observations, the job of devising and testing mechanistic models can be simplified. 43 refs., 13 figs.

Computer technology provides many opportunities to improve the energy performance of commercial buildings throughout the entire building life cycle. We are faced with developing those technologies to put the results of many years of buildings research into the hands of building owners, designers, and operators. This report discusses both the philosophical and technological aspect associated with this topic.

Anti-proton annihilation in a nuclear target can test many novel aspects of quantum chromodynamics. In this talk I discuss a number of interesting features of such processes, including the formation of nuclear-bound quarkonium, tests of color transparency in hard, quasi-elastic nuclear reactions, higher-twist, coherent, and formation zone effects in hard inclusive nuclear reactions, reduced amplitude predictions for exclusive nuclear amplitudes, and color filter effects inclusive open and hidden charm production in nuclei. 43 refs., 6 figs., 2 tabs.

The expected buildup of co-deposited tritium on the CIT carbon divertor and first wall surfaces and operational methods of minimizing the inventory have been examined. The analysis uses impurity transport computer codes, and associated plasma and tritium retention models, to compute the thickness of redeposited sputtered carbon and the resulting co-deposited tritium inventory on the divertor plates and first wall. Predicted erosion/growth rates are dominated by the effect of gaps between carbon tiles. The overall results appear favorable, showing stable operation (finite self-sputtering) and acceptably low ({approximately}25 Ci/pulse) co-deposited tritium rates, at high surface temperature (1700{degree}C) design conditions. These results, however, are highly speculative due to serious model inadequacies at the high sputtering rates predicted. If stable operation is obtainable, the prospects appear good for adequate tritium inventory control via helium-oxygen glow discharge cleaning. 25 refs.

Major trends of the physics program related to the study of hadron structure and hadron spectroscopy at the new high current, high duty cycle electron machines are discussed. It is concluded that planned experiments at these machines may have important impact on our understanding of the strong interaction by studying the internal structure and spectroscopy of the nucleon and lower mass hyperon states.

The status of hadronic and electromagnetic excitation of light quark (u, d) baryon states is reviewed and confronted with results of calculations within the framework of microscopic model of the baryon structure and the photon - baryon coupling. Prospects for a qualitative improvement of our knowledge in this sector using photon and electron beams at the new, intermediate energy cw electron machines are discussed.

Double-resonance, Resonance Ionization Mass Spectroscopy (RIMS) using two single-frequency dye lasers and a CO{sub 2} laser for photoionization has been shown to be both extremely sensitive and highly selective. Measurements on the radioisotope {sup 210}Pb have demonstrated optical selectivity in excess of 10{sup 9} and detection limits of less than 1 femtogram.

The completion of additional radiation shielding in the spring of 1989 has allowed the DIII-D tokamak to enter a new phase of experimental operation, in which the potential of injecting deuterium beam injection into deuterium plasmas has been exploited. The benefit of the isotope effect in increased energy confinement time, and increased power delivery by the neutral beam injectors, has been used to extend the machine performance. Plasma beta values ({beta}{sub T} {le} 10.7%) near expected theoretical limits (3.5 I/aB) have been obtained and high energy content discharges with {beta}{sub T} = 5.2% have been achieved at full magnetic field (2.1 T). The stored energy has reached 3.6 MJ and diverted plasmas with 3 MA have been produced. Enhanced (H-mode) energy confinement plasmas have been maintained for over 10 seconds with no indication of impurity accumulation. This paper presents a brief description of the shielding design; a discussion of the performance improvements of the neutral beam ion sources with deuterium; an overall review of plasma parameters achieved recently in the DIII-D tokamak; and a presentation of new hardware systems being brought on line (e.g. Advanced Divertor, Fast Wave Current Drive, and 110 GHz ECH). 9 refs., 4 figs., 1 tab.