Damage nucleation in single crystals of silicon during ion irradiation is investigated. Experimental results and mechanisms for damage nucleation during both room and liquid nitrogen temperature irradiation with different mass ions are discussed. It is shown that the accumulation of damage during room temperature irradiation depends on the rate of implantation. These dose rate effects are found to decrease in magnitude as the mass of the ions is increased. The significance of dose rate effects and their mass dependence on nucleation mechanisms is discussed.

Microscopic and semi-classical descriptions of octupole deformation are compared. New semi-classical results, obtained with the use of a Woods-Saxon potential are presented. Comparisons with experiment are made. 21 references.

Results of three experiments will be described. We used 351-nm and 355-nm pulses with durations of 0.6, 1, 5 and 9 ns measure thresholds for a variety of anti-reflectance and high reflectance coatings. The functional form t/sup m/, with t the pulse duration, was used to scale fluence thresholds measured at 0.6 ns to those measured at 9.0 ns. Values of the coefficient m ranged from 0.10 to 0.51. The average value was 0.30. In the second experiment, we measured thresholds at 1064 nm, 527 nm and 355 nm for single-frequency high reflectance ZrO/sub 2//SiO/sub 2/ coatings. Coatings for all three frequencies were deposited simultaneously by use of masks in the coating chamber. Thresholds varied from 2 to 4 J/cm/sup 2/ at 355 nm to 7 to 10 J/cm/sup 2/ at 1064 nm. The third experiment measured thresholds at 355 nm for antireflection coatings made with layer thicknesses varying from greater than one wavelength to less than a quarterwavelength. A significant variation of threshold with coating thickness was not observed, but the median thresholds increased slightly as coating thickness increased.

The ATF experiment will test improvements to high-beta, steady-state toroidal confinement using external helical fields. The device design has been optimized to (1) provide direct access to the high-beta second-stability regime, (2) have sufficient flexibility to study a large range of toroidal configurations both with and without plasma current, (3) test the reduction of low-collisionality transport by EXB drifts induced by the self-consistent radial electric field, and (4) permit steady-state, high-beta operation without disruptions. Continued physics studied at ORNL and recent results from foreign stellarator experiments have increased confidence in ATF performance.

As part of the safety assessment in the design of the glass melter for large-scale immobilization of high-level radioactive wastes, structural considerations of the containment shell include its dynamic responses to abnormal loading conditions such as that caused by a steam explosion. The postulated steam explosion, conservatively given an energy content equivalent to 13 pounds of TNT, is capable of exerting sudden pressures greater than 300 psi but less than 410 psi on the melter wall. By use of thin-shell theory, the equations of motion satisfying the discontinuity conditions at junctions of shells with different curvatures are solved analytically. Results of stress analysis ensure elastic responses of the containment structure of the melter. 6 references, 3 figures, 1 table.

The most common asbestos materials used at the Savannah River site include: steam pipe insulation; powerhouse boiler insulation; wallboards; roofing materials; and cement products. Asbestos was also found in a number of other materials: aprons; gaskets; laboratory hot pads; and talcum powder used for gloves. Techniques for removal; personnel training; mechanical ventilation; and personnel isolation techniques are described for completing asbestos removal safely and without boiler downtime. (PSB)

This paper presents an overview of the EPICS control system at FERMILAB. EPICS is a distributed, multi-user, interactive system for the control and monitoring of particle beamlines at a high-energy experimental physics laboratory. The overview discusses the operating environment of the control system, the requirements which determined the design decisions, the hardware and software configurations, and plans for the future growth and enhancement of the present system. This paper is the first of three related papers on the EPICS system. The other two cover (1) the system structure and user interface and (2) RSX implementation issues.

A review is given on current neutron scattering experiments at Brookhaven National Laboratory on transition-metal ferromagnets Ni, Fe, Pd/sub 2/MnSn and MnSi. The scattering intensity in constant-energy scans, observed above T/sub c/ in all of these materials, exhibited a clear peak at finite momentum transfers. Using a simple scattering function with double-Lorentzian shape, we demonstrate that this peak is a manifestation of simple diffusive spin fluctuations. Experimental results of several parameters are compared in the context of localized-moment and itinerant-electron pictures. The ratio of spin wave stiffness constant D and transition temperature kT/sub c/ is shown to be a good yardstick for the degree of itinerancy of d-electrons. 36 references.

A computer code (MIGRAT) is used to quantify the migration of moisture and multiple retarded contaminants in the unsaturated zone and assess the impact of open mine disposal of uranium mill tailings. The model is applied to a generic uranium mill tailings. The model is applied to a generic uranium mill tailings pit constructed with a clay-lined bottom and steep unlined sidewalls. The migration of a two contaminant system is modeled assuming that neither contaminant decays and only one contaminant is retarded. This study shows the anticipated result that the major pathway from the pit to the underlying water table is through the sidewall and that the time scales for this pathway are much shorter than those associated with the clay liner. More importantly, this study reveals that due to the strong nonlinear character of the hydraulic properties of unsaturated soils, concentrations of the retarded contaminant may only slightly lag the nonretarded contaminant through this pathway and contamination of the uppermost aquifer by the retarded contaminant may occur shortly after contamination by the nonretarded contaminant. 2 references, 5 figures.

Recently, there has been considerable interest in the central rapidity region of highly relativistic heavy-ion collisions. Such an interest stems from the possibility of creating hadron matter of high energy density which may exceed the critical energy density for a phase transition between ordinary confined matter and the unconfined quark-gluon plasma. The experimental searches and identification of the quark-gluon plasma may provide a new insight into the question of quark confinement. The estimate of the initial energy density is quite uncertain. The initial energy density is nonetheless an important physical quantity. It is one of the factors which determines whether the produced matter can undergo phase transition or not. The energy density has been estimated previously by using the color neutralization model of Brodsky et al. However, the color neutralization model gives a central rapidity multiplicity in heavy-ion collision too low by a factor of two. For this reason, we wish to obtain a better estimate of the energy density (in the central rapidity region). As is well known, a simple Glauber-type multiple collision model can reproduce the total multiplicity and multiplicity plateau near the central rapidity region to within 30%. The simple multiple collision model has an approximate validity …

The exchange badge system which was used at the Plutonium Facility located in Technical Area 55 was replaced on a trial basis with an automated Entry Control System. As a result of the success of the trial system, a new system incorporating expanded features and increased reliability is being implemented. The new Entry Control System incorporates several features not previously available in relatively inexpensive entry systems. The reliability of the system is enhanced by redundant microprocessors incorporating bubble memory for nonvolatile storage of the system data base. The badge readers incorporate dual communication lines to two different controllers to further increase the total system reliability.

Stimulated Raman scattering of an XeCl laser at 308 nm in a high pressure H/sub 2/ cell shows anomalously high conversion into first Stokes (S1) when a pumping geometry with a Fresnel number near unity is used. Specifically a quantum efficiency of 88% is obtained into S1. Comparison with a plane-wave model indicates that a theory including diffraction and 4-wave mixing may be necessary to understand the anomalous holdoff of the second Stokes component. 10 references.

We consider a zero-..beta.. spheromak contained in a rectangular region having perfectly conducting boundaries in its minimum energy state, and we calculate its evolution. Our results may be summarized as follows. Since this state is a stable equilibrium, the initial evolution of the plasma is caused by diffusion. We simulate this using a transport code. We find that q at the magnetic axis drops and q(r) becomes flat. When q on axis drops below 0.5, the spheromak becomes unstable to an n = 2 kink. The plasma is then modeled dynamically; the kink displacement saturates and eventually reverses when a reconnection occurs. A new magnetic axis begins to form as the plasma relaxes toward a minimum energy state.

A computer-controlled multichannel analysis system has been developed by the Radiological Survey Activities Group at Oak Ridge National Laboratory (ORNL) for the Department of Energy (DOE) in support of the DOE's remedial action programs. The purpose of this system is to provide a rapid estimate of the /sup 226/Ra concentration in soil samples using a 6 x 9-in. NaI(Tl) crystal containing a 3.25-in. deep by 3.5-in. diameter well. This gamma detection system is controlled by a mini-computer with a dual floppy disk storage medium. A two-chip interface was also designed at ORNL which handles all control signals generated from the computer keyboard. These computer-generated control signals are processed in machine language for rapid data transfer and BASIC language is used for data processing.

The Mirror Fusion Test Facility is a major magnetic fusion energy project at the Lawrence Livermore National Laboratory. An important component of this facility is the vacuum vessel, which forms the vacuum chamber. The vessel is supported on twenty-two pairs of legs that rest on reinforced concrete piers. In performing static and dynamic analyses on the vacuum vessel, we separately investigated the load distribution under gravity loads, pressure loads, electromagnetic loads, and thermal loads. We also performed sophisticated dynamic analyses to predict the structural behavior under a postulated earthquake. The modeling assumptions and analytic procedures are highlighted in this paper.

The calibration factor for albedo neutron dosimeters varies greatly depending upon the energy of the neutrons in the exposure. Calibration results obtained over an eight-year period at each Lawrence Livermore National Laboratory facility where neutron exposure may occur were reviewed. A stronger relationship than expected was found between the ratio of the readings of the 9-in. to 3-in. spheres and the percent thermal. Readings from personnel and albedo badges were reviewed. The readings were consistent with the use of a calibration factor for the albedo dosimeter which varies with changes in the ratio of the personnel and albedo dosimeter TLD readings. 2 references, 6 figures. (ACR)

Some recent transport studies of field-reversed configurations (FRC) during their equilibrium phase are presented. The FRC confinement times of interest tau/sub N/, tau/sub E/, and tau/ sub phi/ are for particles, energy, and trapped-flux, respectively. An analytical expression for tau/sub N/ based on Lower-Hybrid-Drift (LHD) resistivity is presented. Some progress in assessing the respective contributions of radiation and thermal conduction to tau/sub E/ is given. Finally, the relation tau/sub E/ less than or equal to tau/sub phi/ is discussed.

The electromagnetics of one of several techniques for generating FRCs in a coaxial configuration has been presented. It has been shown that the discussed design satisfies all the electromagnetic requirements for a slow source. The next major issue is the investigation of the plasma physics which will ultimately determine the viability of this concept.

An expression to predict the onset of growth of a crack in a quasibrittle material is derived. An energy criterion essentially equivalent to the first two laws of thermodynamics is employed. The criterion is applied to the elastic-plastic crack of Olesiak and Wnuk (1968). 12 references, 3 figures. (ACR)

Charged particle exclusive data for high multiplicity U on U events are reported. Analyses are based on comparison with Cugnon's intranuclear cascade model, and the explosion-evaporation simulation of Fai and Randrup. The azimuthal structure of the observed events shows evidence of collective flow. The widely used flow angle methodology proves to be relatively insensitive to collective effects under the conditions of the present experiment. An isotropic pattern of ejectile emission is not reached at maximum multiplicity. 18 refs., 4 figs.

We study the possibility of extending the model used by Moeller and Nix in 1980 to calculate nuclear masses and fission barriers for nuclei throughout the periodic system, to describe compressibility effects and the existence of a neutron skin. 9 references. (WHK)

Liquid metal corrosion can be an important consideration in developing alloys for fusion and fast breeder reactors and other applications. Because of the many different forms of liquid metal corrosion (dissolution, alloying, carbon transfer, etc.), alloy optimization based on corrosion resistance depends on a number of factors such as the application temperatures, the particular liquid metal, and the level and nature of impurities in the liquid and solid metals. The present paper reviews the various forms of corrosion by lithium, lead, and sodium and indicates how such corrosion reactions can influence the alloy development process.

A radial transport code for Field-Reversed Configurations (FRCs) is described. Assuming quasi-neutrality and neglecting inertia and viscous force, the evolution of particle densities, temperatures, and magnetic field through a series of equilibrium states is simulated. To solve the equations, transformations of all dependent variables and the one independent variable are carried out. The processes of interest can be decoupled into two distinctive sets of equations that describe adiabatic and nonadiabatic processes. These sets of equations are then solved by two alternating steps adiabatic and nonadiabatic.

The CONCEPT code generates capital cost estimates based on the following premise: any central station power plant involves approximately the same major cost components regardless of the location or date of initial operation.