In this paper the physical packaging and the logical organization of the Liquid Argon Calorimeter (LAC) electronics system for the Stanford Linear Collider Large Detector (SLD) at SLAC are described. This system processes signals from approximately 44,000 calorimeter towers and is unusual in that most electronic functions are packaged within the detector itself as opposed to an external electronics support rack. The signal path from the towers in the liquid argon through the vacuum to the outside of the detector is explained. The organization of the control logic, analog electronics, power regulation, analog-to-digital conversion circuits, and fiber optic drivers mounted directly on the detector are described. Redundancy considerations for the electronics and cooling issues are discussed. 12 refs., 5 figs.

There has been considerable interest in the complexation of metals and other cations by natural humic and fulvic acids, as well as synthetic polyelectrolytes. In order to explain the binding observed for metals, and other species by organic polyelectrolytes, steric effects have been proposed. In this work, the effects of pH changes in aqueous solution on two synthetic polyelectrolytes, polymaleic acid (PMA) and polyacrylic acid (PAA), have been examined by laser Raman spectroscopy and turbidity measurements. These results are compared to Fourier-transform infrared (FTIR) and (/sup 13/C) nuclear magnetic resonance (NMR) spectra for solid samples of PMA, PAA, and fulvic and humic acids. Two types of carboxylic acid groups were detected for PMA in aqueous solution. Crystallization of PMA in a narrow pH range was observed. These data are consistent with strong intramolecular hydrogen bonding occurring in PMA at a pH of approximately 4. This implication of these results on the use of these compounds as models for fulvic and humic acids is discussed. 27 refs., 3 figs., 1 tab.

Models based on general equations for the excess Gibbs energy of the aqueous fluid provide thermodynamically consistent structures for evaluating and predicting aqueous electrolyte properties. These equations yield other quantities upon appropriate differentiation, including osmotic and activity coefficients, excess enthalpies, heat capacities, and volumes. For this reason a wide array of experimental data are available from which model parameters and their temperature or pressure dependence can be evaluated. For systems of moderate concentration, the most commonly used model at present is the ion-interaction approach and coworkers. For more concentrated solutions, including those extending to the fused salt, an alternate model based on a Margules-expansion and commonly used for nonelectrolytes was proposed. We discuss these two models and give examples of parameter evaluations for some geologically relevant systems to high temperatures and pressures; also we show applications of the models to calculations of solubility equilibria.

A new version of a Two-Beam Accelerator is proposed in which in each period of the drive structure a very small input microwave signal is amplified to a large power level and then completely removed and transferred to the accelerating structure. In this manner a number of difficulties with the original version are eliminated or greatly relieved; namely, rf phase and amplitude sensitivity, growth of sidebands, and rf manipulation (removal of the microwaves from the drive structure, and transmission of microwave power through the accelerating cavities). 11 refs., 6 figs., 2 tabs.

We report on the design of silicon PIN diode array hybrids for use as charged particle detectors. A brief summary of the need for vertex detectors is presented. Circuitry, block diagrams and device specifications are included. 8 refs., 7 figs., 1 tab.

Major differences between fusion drivers and traditional accelerators include the following. The final beam current needed (/approximately/20 kA in a short pulse) is very much larger for a driver; such beams are dominated by repulsive space-charge effects since, even at 10 GeV, the ions are non-relativistic (v/c = 0.3). Also, the optical quality of the beams (called emittance by accelerator people) must be extremely good to ensure a suitably small focal spot at the pellet. Two schemes, one with a rf linac and storage rings, the other with a single-pass current-amplifying induction linac, are under study, the latter exclusively in the US. The induction linac approach lends itself to an examination in a sequence of scaled-down laboratory experiments since the most difficulties are expected to occur at the low energy end. Experiments and simulation have centered on a study of the transverse and longitudinal control of space-charge-dominated beams which are best described in terms of a non-neutral plasma rather than the traditional single-particle dynamics picture. An understanding of the high-current instability limits is required for arriving at a safe driver design. The final on-target beam current is so high that it must be carried in 16 separate focusing channels leading …

The design of future Engineering Test Reactor (ETR) to demonstrate ignition is complicated by the uncertainties in the projected database for ignited plasmas. Application of uncertainty analysis to ETR design utilizing a figure-of-merit defined as the probability of ignition is presented. Performance evaluation from the uncertainty analysis in density-temperature space can locate an optimum operating window for ignition. 11 refs., 5 figs., 3 tabs.

Conceptual design of a bright electron injector for the 1 GeV high gradient test experiment. envisaged by the LLNL-SLAC-LBL collaboration on the Relativistic Klystron is presented. The design utilizes a high-brightness laser-driven RF photocathode electron gun, similar to the pioneering LANL early studies in concept (different parametrically however), together with achromatic magnetic bunching and transport systems and diagnostics. The design is performed with attention to possible use in an FEL as well. A simple but realistic analytic model including longitudinal and transverse space-charge and RF effects and extensive computer simulation form the basis of the parametric choice for the source. These parameters are used as guides for the design of the pico-second laser system and magnetic bunching section.

This paper gives an overview on high energy electron (positron) polarimeters by describing in more detail the plans for the LEP polarimeter and the CEBAF polarimeters. Both LEP and CEBAF will have laser polarimeters. In addition CEBAF will be equipped with a Moller polarimeter (for currents below 1 micro-amp).

The Modular High-Temperature Gas-Cooled Reactor (MHTGR) is an advanced reactor concept being developed under a cooperative program involving the US Government, the utilities and the nuclear industry. This plant design utilizes basic High Temperature Gas-Cooled Reactor (HTGR) features of ceramic fuel, helium coolant, and a graphite moderator. The MHTGR design approach leading to exceptional safety performance also leads to plant operation which is characterized by extremely low radiological emissions even for very low probability accidents. Coated fuel particles retain radionuclides within the fuel, thus minimizing material contamination and personnel exposure. The objective of this paper is to characterize radioactive effluents expected from the normal operation of an MHTGR. In addition, other nonradioactive effluents associated with a power generating facility are discussed. Nuclear power plants produce radioactive effluents during normal operation in gaseous, liquid and solid forms. Principal sources of radioactive waste within the MHTGR are identified. The manner in which it is planned to treat these wastes is described. Like other reactors, the MHTGR produces nonradioactive effluents associated with heat generation and chemical usage. However, due to the MHTGR's higher efficiency, water usage requirements and chemical discharges for the MHTGR are minimized relative to other types of nuclear power plants. …

Ultra-high gradient radio frequency linacs powered by relativistic klystrons appear to be able to provide compact sources of radiation at XUV and soft x-ray wavelengths with a duration of 1 picosecond or less. This paper provides a tutorial review of the physics applicable to scaling the present experience of the accelerator community to the regime applicable to compact linear light sources. 22 refs., 11 figs., 21 tabs.

The turnon experience and initial operating parameters of the SLAC Linear Collider positron source are described. 6 refs., 7 figs.

On April 26, 1986 the world's worst nuclear power plant accident occurred at the Unit 4 of the Chernobyl Nuclear Power Station in the USSR. This paper presents a discussion of the design of the Chernobyl Power Plant, the sequence of events that led to the accident and the damage caused by the resulting explosion. The structural design features that contributed to the accident and resulting damage will be highlighted. Photographs and sketches obtained from various worldwide news agencies will be shown to try and gain a perspective of the extent of the damage. The aftermath, clean-up, and current situation will be discussed and the important lessons learned for the structural engineer will be presented. 15 refs., 10 figs.

This paper describes the kind of computing resources it may be possible to make available for experiments in high energy physics in the mid and late 1990s. We outline some of the work going on today, particularly at Fermilab's Advanced Computer Program, that projects to the future. We attempt to define areas in which coordinated R and D efforts should prove fruitful to provide for on and off-line computing in the SSC era. Because of extraordinary components anticipated from industry, we can be optimistic even to the level of predicting million VAX equivalent on-line multiprocessor/data acquisition systems for SSC detectors. Managing this scale of computing will require a new approach to large hardware and software systems. 15 refs., 6 figs.

The statistical-mechanical treatment of turbulence is made questionable by strong nonlinearity and strong disequilibrium that result in the creation of ordered structures imbedded in disorder. Model systems are described which may provide some hope that a compact, yet faithful, statistical description of turbulence nevertheless is possible. Some essential dynamic features of the models are captured by low-order statistical approximations despite strongly non-Gaussian behavior. 31 refs., 5 figs.

Several genes involved in mammalian DNA repair pathways were identified by complementation analysis and chromosomal mapping based on hybrid cells. Eight complementation groups of rodent mutants defective in the repair of uv radiation damage are now identified. At least seven of these genes are probably essential for repair and at least six of them control the incision step. The many genes required for repair of DNA cross-linking damage show overlap with those involved in the repair of uv damage, but some of these genes appear to be unique for cross-link repair. Two genes residing on human chromosome 19 were cloned from genomic transformants using a cosmid vector, and near full-length cDNA clones of each gene were isolated and sequenced. Gene ERCC2 efficiently corrects the defect in CHO UV5, a nucleotide excision repair mutant. Gene XRCC1 normalizes repair of strand breaks and the excessive sister chromatid exchange in CHO mutant EM9. ERCC2 shows a remarkable /approximately/52% overall homology at both the amino acid and nucleotide levels with the yeast RAD3 gene. Evidence based on mutation induction frequencies suggests that ERCC2, like RAD3, might also be an essential gene for viability. 100 refs., 4 tabs.

The asymptotic properties of the low-degree solar gravity modes classified by Hill and Gu are studied in the framework of first- and second-order asymptotic theory predictions. The results of this analysis demonstrate the necessity of retaining the second-order term in asymptotic theory to describe the eigenfrequency spectrum. In this theory, there are two first-order parameters, T/sub 0/ and delta, and two second-order parameters, V/sub 1/ and V/sub 2/. Values of the parameters obtained in this analysis are: T/sub 0/ = 36.31 +- 0.12 min, delta = /minus/0.43 +- 0.13, V/sub 1/ = 0.35, and V/sub 2/ = 4.76. There remain differences of approx.0.3 ..mu..Hz between the asymptotic theory eigenfrequencies and observed eigenfrequencies which are quasi-periodic functions of the radial order n for a given value of the degree /ell/. 26 refs., 1 fig., 1 tab.

An array of 34 fast/slow plastic scintillators has been used to identify fragments from the breakup of /sup 16/O, /sup 14/N, and /sup 12/C projectiles at 32.5 MeV/nucleon, scattered by a Au target. The dissociation of /sup 16/O into as many as five charged particles has been observed. The yields of the different channels correlate approximately with the threshold energy for separation of the projectile into the observed fragments. The excitation spectrum of the primary projectile fragment was deduced from the measured positions and kinetic energies of the individual fragments. These spectra show that, although most of the decomposition proceeds through excitation energies within /approximately/20 MeV of the lower particle-decay thresholds, excitation energies extending up to /approximately/80 MeV can be produced in the primary stage of the reaction. This represents a significant acquisition of energy by the projectile. Calculations of the yields based on a sequence of binary decays have been presented. Reactions in which one or two units of charge are acquired by the projectile were also observed. 25 refs., 10 figs.

The experimental evidence regarding a light Higgs boson is reviewed. It is shown that a light Higgs boson with almost any mass between 14 MeV/c/sup 2/ and 1 GeV/c/sup 2/ is still allowed by existing data. The only limit in this range comes from B decay data which, for sufficiently large values of the top quark mass, excludes a Higgs boson with a mass between 2m/sub ..mu../ and /approximately/700 MeV/c/sup 2/. Discussions of light Higgs boson emission in the decays of K, ..pi.., ..mu.., /tau/, /eta/', and GAMMA are also given. 29 refs., 2 figs.

Lattice gauge theory, formulated in terms of invariant integrals over group elements on lattice bonds, benefits from many group theoretical notions. Gauge invariance provides an enormous symmetry and powerful constraints on expectation values. Strong coupling expansions require invariant integrals over polynomials in group elements, all of which can be evaluated by symmetry considerations. Numerical simulations involve random walks over the group. These walks automatically generate the invariant group measure, avoiding explicit parameterization. A recently proposed overrelaxation algorithm is particularly efficient at exploring the group manifold. These and other applications of group theory to lattice gauge fields are reviewed in this talk. 17 refs.

Large solid angle position-sensitive phoswich detectors have been constructed to replace smaller units in an array for detecting medium mass fragments (Z less than or equal to 15) in nuclear experiments. The position information was obtained from a time analysis method. 5 refs., 9 figs.

The search of I = 0 0/sup + +/ mesons is described. We highlight the crucial role played by the states in the 1 GeV region. An analysis program that with unimpeachable data would produce definitive results on these is outlined and shown with present data to provide prima facie evidence for dynamics beyond that of the quark model. We briefly speculate on the current status of the lowest mass scalar mesons and discuss how experiment can resolve the unanswered issues. 30 refs., 6 figs., 1 tab.

An FN tandem laboratory, cofounded by several Lawrence Livermore National Laboratory Divisions, Sandia Livermore, and the University of California Regents, is now operational at Livermore. The accelerator, formerly the University of Washington injector, has been upgraded with SF/sub 6/, Dowlish tubes, and a NEC pelletron charging system. A conventional duoplasmatron, a tritium source, and two Cs sputtering sources will be fielded on the accelerator. Pulsed beams will be available from two source positions. The laboratory has been designed to accommodate up to 19 experimental positions with excellent optics and working vacuum. The facility is unshielded with both accelerator and radiological systems under the control of a distributed microprocessor system. Research activities at the tandem include nuclear physics and astrophysics, materials science and characterization programs, and accelerator mass spectrometry for archaeology, biomedical, environmental and geoscience investigators. 3 refs., 1 fig.

A distributed control system has been designed and installed at the Lawrence Livermore National Laboratory Multi-user Tandem Facility using an extremely modular approach in hardware and software. The two tiered, geographically organized design allowed total system implementation with four months with a computer and instrumentation cost of approximately $100K. Since the system structure is modular, application to a variety of facilities is possible. Such a system allows rethinking and operational style of the facilities, making possible highly reproducible and unattended operation. The impact of industry standards, i.e., UNIX, CAMAC, and IEEE-802.3, and the use of a graphics-oriented controls software suite allowed the efficient implementation of the system. The definition, design, implementation, operation and total system performance will be discussed. 3 refs.