The process of longitudinal compression of a drifting heavy ion pulse to be used as an ICF driver is examined with the aid of particle simulation. Space charge forces play a vital role in halting compression before the final focus lens system is reached. This must take place with minimal growth of transverse emittance and momentum spread. Of particular concern is the distortion of longitudinal phase space by the rounded transverse profile of the longitudinal self-electric field.

Antiferromagnetic (AFM) NiO thin films are grown epitaxially on vicinal Ag(118) substrate and investigated by x-ray linear dichroism (XLD). We find that the NiO AFM spin exhibits an in-plane spin reorientation transition from parallel to perpendicular to the step edges with increasing the NiO film thickness. In addition to the conventional L{sub 2} adsorption edge, x-ray linear dichroism (XLD) effect at the Ni L{sub 3} adsorption edge is also measured and analyzed. The result identifies a small energy shift of the L{sub 3} peak. Temperature-dependent measurement confirms that the observed XLD effect in this system at the normal incidence of the x-rays originates entirely from the NiO magnetic ordering.

We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at the top of the valence and the bottom of the conduction band. For large CdSe quantum dots, the number of iteration steps until convergence decreases by about a factor of 4 compared to previous calculations.

This paper reports the results in the effort to destabilize lithium borohydride for reversible hydrogen storage. A number of metals, metal hydrides, metal chlorides and complex hydrides were selected and evaluated as the destabilization agents for reducing dehydriding temperature and generating dehydriding-rehydriding reversibility. It is found that some additives are effective. The Raman spectroscopic analysis shows the change of B-H binding nature.

Seasonally managed wetlands in the Grasslands Basin ofCalifornia's San Joaquin Valley provide food and shelter for migratorywildfowl during winter months and sport for waterfowl hunters during theannual duck season. Surface water supply to these wetland contain saltwhich, when drained to the San Joaquin River during the annual drawdownperiod, negatively impacts downstream agricultural riparian waterdiverters. Recent environmental regulation, limiting discharges salinityto the San Joaquin River and primarily targeting agricultural non-pointsources, now addresses return flows from seasonally managed wetlands.Real-time water quality management has been advocated as a means ofmatching wetland return flows to the assimilative capacity of the SanJoaquin River. Past attempts to build environmental monitoring anddecision support systems to implement this concept have failed forreasons that are discussed in this paper. These reasons are discussed inthe context of more general challenges facing the successfulimplementation of environmental monitoring, modelling and decisionsupport systems. The paper then provides details of a current researchand development project which will ultimately provide wetland managerswith the means of matching salt exports with the available assimilativecapacity of the San Joaquin River, when fully implemented. Manipulationof the traditional wetland drawdown comes at a potential cost to thesustainability of optimal wetland moist soil plant habitat in thesewetlands - hence the project …

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The objective of this paper is to assess proposed transuranic waste accident analysis guidance and recent software improvements in a Windows-OS version of MACCS2 that allows the inputting of parameter uncertainty. With this guidance and code capability, there is the potential to perform a quantitative uncertainty assessment of unmitigated accident releases with respect to the 25 rem Evaluation Guideline (EG) of DOE-STD-3009-94 CN3 (STD-3009). Historically, the classification of safety systems in a U.S. Department of Energy (DOE) nuclear facility's safety basis has involved how subject matter experts qualitatively view uncertainty in the STD-3009 Appendix A accident analysis methodology. Specifically, whether consequence uncertainty could be larger than previously evaluated so the site-specific accident consequences may challenge the EG. This paper assesses whether a potential uncertainty capability for MACCS2 could provide a stronger technical basis as to when the consequences from a design basis accident (DBA) truly challenges the 25 rem EG.

An international, multiple-code benchmark test (BMT) studyis being conducted within the international DECOVALEX project to analysecoupled thermal, hydrological, mechanical and chemical (THMC) processesin the excavation disturbed zone (EDZ) around emplacement drifts of anuclear waste repository. This BMT focuses on mechanical responses andlong-term chemo-mechanical effects that may lead to changes in mechanicaland hydrological properties in the EDZ. This includes time-de-pendentprocesses such as creep, and subcritical crack, or healing of fracturesthat might cause "weakening" or "hardening" of the rock over the longterm. Five research teams are studying this BMT using a wide range ofmodel approaches, including boundary element, finite element, and finitedifference, particle mechanics, and elasto-plastic cellular automatamethods. This paper describes the definition of the problem andpreliminary simulation results for the initial model inception part, inwhich time dependent effects are not yet included.

This paper presents preliminary results from an ongoing post-irradiation analysis of materials that have been irradiated at the Brookhaven National Laboratory (BNL) Isotope facility. The effort is part of an experimental study that focuses on how prone to irradiation damage these materials are and thus what is their potential in playing the role of high power targets in the neutrino superbeam and the muon collider initiatives.

The spatial distribution of copper ions and atoms in high power impulse magnetron sputtering (HIPIMS) discharges was determined by (i) measuring the ion current to electrostatic probes and (ii) measuring the film thickness by profilometry. A set of electrostatic and collection probes were placed at different angular positions and distances from the target surface. The angular distribution of the deposition rate and the average charge state of the copper species (including ions and neutrals) were deduced.The discharge showed a distinct transition to a high current mode dominated by copper self-sputtering when the applied voltage exceeded the threshold of 535 V. For a lower voltage, the deposition rate was very low and the average charge state was found to be less than 0.4. For higher voltage (and average power), the absolute deposition rates were much higher, but they were smaller than the corresponding direct current (DC) rates if normalized to the same average power. At the high voltage level, the spatial distribution of the average charge state showed some similarities with the distribution of the magnetic field, suggesting that the generation and motion of copper ions is affected by magnetized electrons. At higher voltage, the average charge state increases with the …

As part of the ongoing international DECOVALEX project, fourresearch teams used five different models to simulate coupled thermal,hydrological, and mechanical (THM) processes near underground wasteemplacement drifts. The simulations were conducted for two genericrepository types, one with open and the other with back-filled repositorydrifts, under higher and lower post-closure temperature, respectively. Inthe completed first model inception phase of the project, a goodagreement was achieved between the research teams in calculating THMresponses for both repository types, although some disagreement inhydrological responses are currently being resolved. Good agreement inthe basic thermal-mechanical responses was also achieved for bothrepository types, even though some teams used relatively simplifiedthermal-elastic heat-conduction models that neglect complex near-fieldthermal-hydrological processes. The good agreement between the complexand simplified process models indicates that the basic thermal-mechanicalresponses can be predicted with a relatively high confidencelevel.

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A major goal for commercial applications of fusion reactors is to minimize radioactive wastes and to dispose of them by near-surface burial. There currently are no regulations specifically applicable to fusion wastes but those in force for fission wastes furnish a framework for expected fusion regulations. This paper recommends that all nuclides with half-lives greater than five years be assigned concentration limits as done in 10CFR61 for fission wastes. The paper gives approximate limits for all the significant long half-life sources of gamma radiation in the currently known periodic table. In the absence of working fusion reactors, computer models must be used to estimate the expected actual concentrations of radioactive nuclides. These estimates are needed to guide design parameters to achieve minimum radioactivity in fusion reactors. It is believed that the computer models and nuclear reaction libraries must be much more comprehensive than ordinarily used today to do activation calculations.

This paper explores the impact of an HOL on the development of the distributed computer control system for Nova laser fusion facility. As the world's most powerful glass laser, Nova will generate 150 trillion watt pulses of infrared light focused onto fusion targets a few millimeters in diameter. It will perform experiments designed to explore the feasibility of fusion as an energy source of the future. Nova will utilize fifty microcomputers and four VAX-11/780's in a distributed process control computer system architecture.

The effect of powdered activated carbon on stressed anaerobic digesters utilizing a sewage sludge substrate was evaluated. The addition of carbon resulted in increased methanee production and greater process stability. The degree of enhancement appeared to be proportional to carbon concentration over the dose range studied (500-10,000 mg/l). A maximum increase in methane production of about 150% was observed at the highest carbon dose. The effect of 1500 mg/l carbon, 4000 mg/l coal, and 4000 mg/l flyash on relatively unstressed digesters was also examined. Units using a sewage sludge substrate were operated at 10 and 20 day SRT's. A 12% increase in methane production was observed in a carbon dosed digester functioning at a 10 day detention time. Enhancement was not evident with carbon at a 20 day SRT. No significant improvement in methane production was obtained in any of the digesters using coal or flyash as additives. Using the experimental data, a technique was developed for estimating the efficiencies of the methane forming and acid forming steps in the anaerobic digestion process. The results indicated that in stressed systems both stages of the digestion process were enhanced by the addition of powdered carbon. In the relatively unstressed systems, when …

This article uses 41 Landsat images between 1988 and 2016 to calculate the normalized difference vegetation indices (NVDIs) of the wetland vegetation at Xitugou (XTG) and Wowachi (WWC) inside the Dunhuang Yangguan National Nature Reserve in northwest China in order to assess the impacts of climate change on wetland vegetation.

Enclosed are proceedings of the workshop on Internal Dosimetry held on Atlanta, Georgia in April 1992. The recommendations from the Workshop were considered by the CIRRPC Subpanel on Occupational Radiation Protection Research in identifying those areas to be undertaken by individual Federal Agencies or in cooperative efforts. This document presents summaries of the following sessions: A.1 Applications and limitations of ICRP and other metabolic models, A.2 Applications and implementation of proposed ICRP lung model, A.3 Estimates of intake from repetitive bioassay data, A.4 Chelation models for plutonium urinalysis data, B.1 Transuranium/uranium registry data, B.2 Autopsy tissue analysis, B.3 Bioassay / Whole body counting, B.4 Data base formatting and availability, C.1 An overview of calculational techniques in use today, C.2 The perfect code, C.3 Dose calculations based on individuals instead of averages, C.4 From macro dosimetry to micro dosimetry.

Many workstation based emergency response dispersion modeling systems provide simple Gaussian models driven by single meteorological tower inputs to estimate the downwind consequences from accidental spills or stack releases. Complex meteorological or terrain settings demand more sophisticated resolution of the three-dimensional structure of the atmosphere to reliably calculate plume dispersion. Mountain valleys and sea breeze flows are two common examples of such settings. To address these complexities, we have implemented the three-dimensional-diagnostic MATHEW mass-adjusted wind field and ADPIC particle-in-cell dispersion models on a workstation for use in real-time emergency response modeling. Both MATHEW and ADPIC have shown their utility in a variety of complex settings over the last 15 years within the Department of Energy`s Atmospheric Release Advisory Capability project.

Several pumping mechanisms have been suggested for x-ray lasers including collisional excitation, recombination, photo-ionization and photo-pumping. The success of photo-pumping as an x-ray laser scheme hinges on sufficient overlap of the emission and adsorption lines. For such a scheme to exhibit gain, the difference of the energies of the two lines must be within the line widths determined by the plasma dynamics, such as Doppler and opacity broadening. Typically, an overlap of a few parts in 10{sup 4} is required. Due to correlation effects, high-n levels of multi-electron ions are difficult to calculate and are reliable to roughly a part in 10{sup 3}. These differences are large enough to preclude accurate predictions of successful overlaps. As a result, precise measurements of the overlaps are needed. The continued interest in photo-pumping schemes lies in its potential to improve the laser output. It also allows the excitation of lasing transitions not accessible to other mechanisms and thus to the test laser kinetics from a different perspective. We have studied several such photo-pumping schemes at the LLNL electron beam ion trap. The N-like isoelectronic sequence 3d-5f and 3d-6f transitions were studied for photo-pumping by He-like ions, the Ne-like 2p-4d transitions were studied for …

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Using the dielectric wall accelerator technology, they are developing a compact induction accelerator system primarily intended for pulsed radiography. Unlike the typical induction accelerator cell that is long compared with its accelerating gap width, the proposed dielectric wall induction accelerator cell is short and its accelerating gap width is comparable with the cell length. In this geometry, the RF modes may be coupled from one cell to the next. They will present recent results of RF modeling of the cells and a prediction of the transverse beam instability on a 2-kA, 8-MeV beam.

The principle of sufficient reason asserts that anything that happens does so for a reason: no definite state of affairs can come into being unless there is a sufficient reason why that particular thing should happen. This principle is usually attributed to Leibniz, although the first recorded Western philosopher to use it was Anaximander of Miletus. The demand that nature be rational, in the sense that it be compatible with the principle of sufficient reason, conflicts with a basic feature of contemporary orthodox physical theory, namely the notion that nature's response to the probing action of an observer is determined by pure chance, and hence on the basis of absolutely no reason at all. This appeal to pure chance can be deemed to have no rational fundamental place in reason-based Western science. It is argued here, on the basis of the other basic principles of quantum physics, that in a world that conforms to the principle of sufficient reason, the usual quantum statistical rules will naturally emerge at the pragmatic level, in cases where the reason behind nature's choice of response is unknown, but that the usual statistics can become biased in an empirically manifest way when the reason for …

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The High-Resolution Mid-Atlantic Forecasting Ensemble (HME) is a federated effort to improve operational forecasts related to precipitation, convection and boundary layer evolution, and fire weather utilizing data and computing resources from a diverse group of cooperating institutions in order to create a mesoscale ensemble from independent members. Collaborating organizations involved in the project include universities, National Weather Service offices, and national laboratories, including the Savannah River National Laboratory (SRNL). The ensemble system is produced from an overlapping numerical weather prediction model domain and parameter subsets provided by each contributing member. The coordination, synthesis, and dissemination of the ensemble information are performed by the Renaissance Computing Institute (RENCI) at the University of North Carolina-Chapel Hill. This paper discusses background related to the HME effort, SRNL participation, and example results available from the RENCI website.