The effects of the angular range of data taking in reconstructions in planar positron cameras using the deconvolution method and the matrix method, respectively, are investigated. It is found that in the absence of any a priori information there are undetermined components in the reconstruction if the field of view of the positron camera is limited. However, most of the undetermined components are recovered in the case in which the transverse spacing of the object is discrete, and all of them are recovered if the fact that the object extent is finite is utilized. It is concluded that the two reconstruction methods are mathematically equivalent. The results obtained can be applied to other transmission and emission imaging devices.

The ..gamma.. rays from neutron capture in the 0- resonance of /sup 107/Ag at 16.3 eV were studied. Thirteen primary transitions populate spin 1 levels in /sup 108/Ag below an energy of 1.5 MeV. Transitions from low lying levels change in intensity by as much as a factor of 2 between thermal neutron capture (largely spin 1) and the 0- resonance, indicating a strong correlation of the population with level spin. 7 references.

Electric power systems that have major loads and generation centers separated by large distances may experience low-frequency power oscillations. This type of oscillation has occurred on the Pacific ac intertie that connects southern California and the Pacific Northwest. A separate, almost parallel, dc-transmission line also connects these areas. The Bonneville Power Administration, which operates this transmission system, has overcome the instability by controlling the power transmitted on the dc-transmission line. A 30-MJ (8.4-kWh) superconducting magnetic energy storage unit with a 10-MW converter could also provide damping for this instability. The conceptual design of the 30-MJ coil and the cryogenic and electrical components of the system are described. The system is to operate at a maximum current of 5 kA and will modulate the ac Intertie at 0.35 Hz. Discharge will be controlled to retain a minimum stored energy of 20 MJ to limit cyclic strains in the coil and ac losses in the conductor. The conductor will be made of multistrand-copper and copper-matrix, multifilament NbTi superconducting wires on a stainless steel mandrel.

The Antares laser will require that about 100 high-precision NaCl windows of 18-in. diameter be produced, maintained, and repaired. To aid the industry in achieving the required production rates, a polishing development program was undertaken by LASL's Laser Division in collaboration with the Air Force and International Laser Systems. The design and initial shakedown of the polishing machine is described. Preliminary results indicate the machine's design is sound, its operation is generally simple, and it should be capable of finishing 18-in. NaCl to better than lambda/2 visible and 20-10 surface. Shakedown work with glass has demonstrated 0-0 surface, complete absence of edge roll, and lambda/16 over 12 in., and lambda/6 over 19 in.

A 150-kV, 80-A power supply and neutral beam test facility is now operational at the Lawrence Berkeley Laboratory, Berkeley, California. This supply uses banks of 450-V electrolytic capacitors for over 10/sup 6/ joules of energy storage. SCR switches control the power flow to the neutral beam accelerator. Turn on and off times of a few microseconds are possible. An auxiliary capacitor bank also uses SCR switches to provide regulation (''flat-topping'') of the main bank output by switching in additional capacitors as the main bank discharges. Air-operated switches are used to connect the main-bank sections in parallel for charging and series or parallel for discharge, depending on the operating voltage desired. A single digital switch sets the desired operating voltage. Filament and arc power supplies are also solid state. With the exception of the suppressor supply which has one vacuum tube the complete neutral beam system uses all solid state components.

This paper discusses results of plasma-confinement experiments in the 2XIIB magnetic mirror device. We report experiments attempting to achieve field-reversal using neutral-beam injection in which the central magnetic field is reduced by 90% but field lines are not closed. Experiments with different neutral-beam aiming show that at constant beta both electron temperature and the energy-confinement parameter (n tau) increase at larger radius. Finally, we discuss recent improvements in electron temperature and microinstability measurements.

The use of ab initio molecular orbital calculations to aid in the characterization, i.e., structures and energies, of metal halide complexes present in high temperature salt vapors has been investigated. Standard LCAO-SCF methods were used and calculations were carried out using the minimal STO-3G basis set. The complexes included in this study were Al/sub 2/F/sub 6/, Al/sub 2/Cl/sub 6/, AlF/sub 3/ NH/sub 3/, AlCl/sub 3/ NH/sub 3/, and AlF/sub 3/ N/sub 2/. The Al/sub 2/X/sub 6/ complexes are found to have D/sub 2h/ symmetry in agreement with most experimental results. A planar form was found to be considerably higher in energy. The AlX/sub 3/ NH/sub 3/ complexes are found to have C/sub 3v/ symmetry with a small barrier to rotation about the Al-N axis. The AlF/sub 3/ N/sub 2/ complex is found to be weakly bound together with a binding energy of -8.2 kcal/mole at the STO-3G level.

The absolute radiative widths for E-1 and M-1 transitions in /sup 46/Sc were determined by neutron time-of-flight spectrometry. The level structure of /sup 46/Sc to 3 MeV has been studied by combining (n,..gamma..) data with previous charged particle data. As in /sup 36/Cl, scandium shows enhanced M-1's. 5 references.

LASNEX calculations for focused laser beams on spherical targets have been performed for laser wavelengths of 0.25, 0.5, 1.0 and 2.0 microns. One-dimensional calculations, including the ponderomotive force, show a profile steepening that determines the fractional absorption by anomalous mechanism. However, increased absorption occurs at the shorter wavelengths because of more efficient inverse bremsstrahlung absorption at the higher critical densities. In general, the absorption efficiency increases with shorter laser wavelength and decreases with increasing f-number of the illuminating optics for sufficiently long plasma scale lengths. The effect of the absorption and laser wavelength on the thermal and superthermal electron physics will be discussed along with the combined effects on the implosion performance. Certain aspects of two-dimensional LASNEX calculations are presented.

We report measurements of the absolute and relative abundances, differential energy spectra, and spectral indices for cosmic-ray nuclei from Li to Fe for 2 to 150 GeV/nucleon. These measurements were made using a balloon-borne superconducting magnetic spectrometer with scintillators and optical spark chambers. The abundances of Li, Be, and B for rigidities below 10 GV/c are consistent with an energy-independent mean interstellar pathlength of 4 1/2 {+-} 1/2 g cm{sup -2} for all propagation models. The abundances of all elements above 10 GV/c are consistent with an interstellar pathlength decreasing with rigidity as R{sup -n} with an index n = 0.6{sub -0.3}{sup +0.4}. All differential source spectra can be fitted by power laws in total energy per nucleon with the same spectral index, which is between 2.5 and 2.6 depending on n. If n is near 0.5 (as for simple diffusion), the source index is 2.54 {+-} 0.03. Relative abundances at the sources are thus energy-independent, and have ratios to solar abundances as a function of first ionization potential which indicate a source temperature between 10{sup 4} and 5 x 10{sup 4} K depending on the equilibrium nature of the injection environment.

The accelerator-driven breeder can extend an essential energy resource, fissile fuel for nuclear reactors, by a very large factor. Symbiotic breeders could be brought on line in a shorter period of time with favorable performance predictability. The economics of using accelerator breeding of fertile-to-fissile elements will become favorable as natural fissile material becomes scarce.

This paper describes a computer-control system for a superconducting linear accelerator currently under development at Argonne National Laboratory. RSX-11M V3.1 running on a PDP 11/34 is used with CAMAC hardware to fully control 22 active beam-line elements and monitor critical accelerator conditions such as temperature, vacuum, and beam characteristics. This paper contrasts the use of an RSX compatible CAMAC driver for most CAMAC I/O operations and the use of the Connect-to-Interrupt Vector directive for fast ADC operation. The usage of table-driven software to achieve hardware configuration independence is discussed, along with the design considerations of the software interface between a human operator and a computer-control system featuring multi-function computer-readable control knobs and computer-writable displays which make up the operator's control console.

The purpose of the program is to develop an experimental/analytical evaluation of the feasibility of detecting and analyzing flaw growth in reactor pressure boundaries by means of continuously monitoring acoustic emission (AE). The investigation is devoted exclusively to ASTM Type A533, Grade B, Class 1 material. The basic approach to interpretive model development is through laboratory testing of 1 to 1/sup 1///sub 2/ inch (25.4 to 38 mm) thick fracture mechanics specimens in both fatigue and fracture at both room temperature and 550/sup 0/F (288/sup 0/C). Seven parameters are measured for each AE signal and related to fracture mechanics functions. AE data from fracture testing of 6 inch (152 mm) wall pressure vessels are also incorporated in analysis.

The simulation of geothermal reservoirs involves the solution of the equations describing multiphase, non-isothermal flow in porous media. These equations are highly nonlinear, particularly as the solution encounters the boundary of the two-phase region. There are essentially as many ways of accommodating this nonlinearity as there are numerical models of geothermal reservoirs. However, there is no universally accepted method for establishing the relative accuracy of these techniques. Well-established methodologies such as Fourier analysis and comparison against analytical solutions are simply not applicable to nonlinear systems. A necessary but not sufficient condition for convergence is the conservation of mass energy and momentum. This information is generally provided as an integral part of the numerical solution.

Acoustic emission is attributed to energy release within a material body by localized plastic deformation or failure processes. The elastic stress waves may come from slip band formation, mechanical twinning, martensite transformation, or crack propagation. Each of these processes has slightly different acoustic characteristics allowing for easy identification. Acoustic emission was monitored during tensile tests of Type 304L austenitic stainless steel to explore the applicability of the technique to hydrogen-assisted fracture.

Acoustic emission is a transient elastic wave generated by the rapid release of energy within a material. A wide variety of mechanisms have been proposed as possible sources of acoustic emission. Proposed mechanisms have included crack propagation, precipitate fracture, twin formation, martensite formation, dislocation motion and/or multiplication. This paper is concerned with acoustic emission generated by dislocation mechanisms operating during plastic deformation. Twinning and martensitic phase transformations are excluded even though dislocation motion is involved in the nucleation and growth of twins and the growth of martensite.

The sources of acoustic emission that are prevalent in brittle solids are examined, especially microcrack sources and sources that accompany macrocrack extension. The emission amplitude distributions are derived using crack opening displacement solutions pertinent to each source type, and assuming an extreme value size distribution of precursors consistent both with the functional form of typical emission amplitude distributions and with defect size observations. Acoustic emission event rates are derived from the stress and time dependence of crack growth. Stress history effects are afforded particular emphasis. Finally, some applications of acoustic emission that emerge from the analysis of the source characteristics are briefly evaluated.

The Los Alamos Scientific Laboratory Hot Dry Rock Geothermal Energy Development Project, under the Department of Energy and in cooperation with Dresser Atlas, has conducted single- and dual-well acoustic measurements to detect fractures in the artificial geothermal reservoir at the Fenton Hill New Mexico experimental site. The measurements were made using modified Dresser Atlas logging tools. Signals traversed distances of from 48 to 150 feet between two wells. Signals intersecting hydraulic fractures in the reservoir under both hydrostatic and pressurized conditions were simultaneously detected in both wells. Upon reservoir pressurization, signals along many ray paths were severely attenuated throughout their entire coda. In addition obvious shear wave arrivals were notably absent. The signals were processed to obtain Full-Wave Acoustic, Power, and Normalized Equi-Power Logs. Analysis of these logs identified the effective ''top'' of a region of hydraulically activated fractures and fractures intersecting the injection well behind casing.

Present techniques for measuring sound velocity in liquid metals have been limited by the use of transducers which cannot survive in extreme temperature conditions. These methods also require relatively long measurement times. An optical noncontacting method has been developed which may be used for extremely short experimental times and very high temperatures and pressures. This technique is being incorporated into an isobaric expansion apparatus in which a 1 mm diam wire sample in a high pressure argon gas environment is resistively heated to melt within a time period of only a few microseconds. Before instability of the liquid column occurs, thermal expansion, enthalpy, and temperature are measured. The addition of the sound velocity measurement permits a more complete determination of the thermophysical properties of the liquid metal.

The SLSF is the largest U.S. in-reactor test vehicle for steady-state and transient experiments in an environment typical of a LMFBR core. The SLSF experiment program, sponsored by the Department of Energy, contributes to the LMFBR safety assurance program by providing data on key phenomena that occur during postulated reactor accidents. This paper describes completed SLSF experiments, in-core instrumentation used, and methods of data interpretation to determine sodium boiling and voiding dynamics. Boiling inception is shown to be identifiable from several types of in-core instruments. Location of the boiling front and void growth derived from experimental data are compared with analytical predictions. These and other data form the basis to improve understanding of accidents and to validate or guide the development of accident analysis methods.

The use of adaptive control techniques is investigated in heating, ventilating, and air cnditioning (HVAC) systems in solar heated and cooled buildings to minimize the consumption of auxiliary energy. Optimal control theory is used in conjunction with the adaptive control techniques to accomplish the minimization of auxiliary energy. The resulting technique is referred to as adaptive optimal control (AOC). This study has been made by computer simulation and is centered on the National Security and Resources Study Center (NSRSC), a large solar heated and cooled building at the Los Alamos Scientific Laboratory (LASL). Simplified models of the building and HVAC system have been developed for both the heating and cooling modes. The control strategies actually used in the NSRSC were simulated in the models and an adaptive optimal controller was developed and also simulated. Simulation runs were made with both the conventional controller and the adaptive controller and performance results of the two simulations were compared. In the first results (obtained using a partial derivative system identification method), the adaptive optimal controller model demonstrated a savings in auxiliary energy of 28.8% for the heating simulation and 18.3% for the cooling simulation when compared to the conventional controller simulation models.

Projections indicate that MJ/MW laser systems, operating with efficiencies in escess of 1 percent, are required to drive laser fusion power reactors. Moreover, a premium in pellet performance is anticipated as the wavelength of the driver laser system is decreased. Short wavelength laser systems based on atomic selenium (lambda = 0.49..mu..), terbium molcular vapors (0.55..mu..), thulium doped dielectric solids (0.46..mu..), and on pulse compressions of KrF excimer laser radiaton (0.27..mu..) have been proposed and studied for this purpose. The technological scalability and efficiency of each of these systems is examined in this paper. All of these systems are projected to meet minimum systems requirements. Amont them, the pulse-compressed KrF system is projected to have the highest potential efficiency (6%) and the widest range of systems design options.

A survey is presented of the advanced research and development projects underway in the U.S. in all of the known media and methods for storing and transferring thermal energy in solar applications. The technologies reviewed include innovative heat exchange and heat transport methods, advanced sensible heat storage in water, rocks, earth and combinations of these for both short term and annual storage, phase change materials, and reversible chemical reactions. This survey is presented in a structure of categories and subcategories of thermal energy storage and heat transfer technology. Within a given subcategory the project descriptions are listed under the name of the organizations conducting the work, arranged in alphabetical order.

The development of a new high-temperature, 350/sup 0/C advanced turbodrill for use in drilling geothermal wells is underway. Existing downhole drilling motors are temperature limited because of elastomeric degradation at elevated temperature. The new turbodrill contains high-torque turbine blades and improved seals which allow higher bit pressure drops. This new geothermal turbodrill which is designed for improved directional drilling offers economic alternatives for completing geothermal wells. The advanced turbodrill will be tested in the Los Alamos Scientific Laboratory's hot dry rock geothermal wells.