Measurement of /sup 129/I at low levels is required for effluent control, environmental assessment and tracer studies in the natural environment. Low level /sup 129/I analysis has also been used for measurement of natural-fission-produced /sup 129/I in minerals and ores as well as meteorites. The most sensitive method for /sup 129/I measurements is neutron activation analysis of iodine separated from a suitable sample. Minimum sample processing prior to neutron activation is desirable in order to reduce chances of sample contamination with uranium or /sup 129/I. A potential interference in the activation analysis method is the production of /sup 129/I (/sup 130/I) from Te impurities in the irradiated ampoule. Procedures have been developed and applied to measurement of the magnitude of the potential Te interference. One-tenth of a microgram of Te in the irradiated ampoule is sufficient to produce interference in the analysis. This is detectable by either radiochemical Te measurements or by /sup 131/I detection in the iodine fraction from the irradiated ampoule. This paper discusses the procedures and results of Te interference studies in /sup 129/I activation analysis. The interference was found to be insignificant for most analyses. 5 tables.

We are investigating the interactive process between turbulent flow and dispersed phase particles. We are focusing on the mechanisms that appear to result in a reduction of local turbulent intensity and a corresponding reduction in wall heat transfer and subsequent wall erosion in turbulent solid propellant combustion flow. We apply computational simulations and physical experiments specialized to a developing free shear layer over a rearward facing step and over a parallel splitter plate. The flow configuration evolves in a two-dimensional, steady, combustion and non-combustion turbulent free shear mixing region, with and without particle additives. The computational simulations combine three basic components: gas phase Navier-Stokes solutions, Lagrange particle field solutions and a Monte Carlo technique for the random encounters, forces and accelerations between the two fields. We concentrate here on relatively large sized additive particles (of the order of tens of microns to 100 microns mean diameter). We examine their apparent influence in breaking up the larger, energy bearing eddy structures into smaller structures which are more readily dissipated.

An equation of state previously used by the author is developed further and applied to geologic media. The equation is of the same form as the Murnaghan equation of state, but with the elastic constant terms replaced by the cohesive energy density (internal pressure), and the exponential term given as a sum of the Gruneisen parameter and the gaseous adiabatic exponent. Data for shock compression of silica, basalt, and dolomite are analyzed according to the equation.

The fusion breeder is a fusion reactor designed with special blankets to maximize the transmutation by 14 MeV neutrons of uranium-238 to plutonium or thorium to uranium-233 for use as a fuel for fission reactors. Breeding fissile fuels has not been a goal of the US fusion energy program. This paper suggests it is time for a policy change to make the fusion breeder a goal of the US fusion program and the US nuclear energy program. The purpose of this paper is to suggest this policy change be made and tell why it should be made, and to outline specific research and development goals so that the fusion breeder will be developed in time to meet fissile fuel needs.

This paper describes the results of a program conducted at Sandia National Laboratories (SNL) for the US Department of Energy to provide an experimental data base for more accurately assessing the radiological consequences from a hypothetical sabotage attack on a spent fuel shipping cask. The primary objectives of the program were limited to: (1) evaluating the effectiveness of selected high explosive devices (HED) in breaching full-size spent fuel casks, (2) quantifying and characterizing relevant aerosol properties of the released fuel, and (3) using the resulting experimental data to evaluate the radiological health consequences resulting from a hypothetical sabotage attack on a spent fuel shipping cask in a densely populated area. Subscale and full-scale experiments in conjunction with an analytical modeling study were performed to meet the programmatic objectives. The data from this program indicate that the Urban Studies greatly overestimated the impact of malevolent acts directed at spent fuel casks in urban environs. From that standpoint this work could be the basis of additional regulatory revisions of the NRC physical protection requirements. In a larger sense this work can also be the basis of more credible worst case analyses since it defines the actual result of an event which is …

In laser driven inertial confinement fusion research, at Livermore, we are diagnosing many phenomena that occur in a time frame that exceeds the capabilities of even the most advanced, present day oscillographic recording instruments. Many of the by-products of the interaction between the laser beam and fuel pellet are monitored to determine the specifics of the fusion process. By the use of appropriate detectors, we convert the information contained in the radiated by-products to electrical signals which are recorded on high bandwidth oscillographic recorders. Our present range of recording capabilities for one x-ray diagnostic measurement in use at Livermore is shown. A commonly used configuration consists of an XRD-31 x-ray detector connected to a direct access Tektronix R7912 transient digitizer using 1/2 in. diameter air dielectric coaxial cable. This configuration gives a system fwhm of approximately 335 ps. Our premier configuration, on the other hand, consists of an improved response detector and a French Thomson-CSF TSN-660 oscilloscope with a shorter length of coaxial cable (typically 20 feet). The system fwhm in this case is less than 120 ps which is our fastest oscillographic recording system at the present time.

Several general approaches to remote servicing are briefly described for the LLL Field Reversed Mirror and Tandem Mirror Fusion reactors. Remote servicing system design considerations for the blanket module are briefly discussed. (RME)

This article explores light-trapping enhancement in newly discovered graded photonic super-crystals (GPSCs) with dual periodicity and dual basis.

The diagnostic data from the MTX experiment is acquired and processed by an expandable, distributed, multivendor computer network. The system blends a variety of software into a coordinated, unified, and highly flexible design. Using modular software design techniques, we created a system stressing distributed processing, portability, and transparent data access. In our approach to modularity, we standardized communication interfaces between modules and separated generic tasks from machine and application-specific implementations. For flexible distributed processing, we used modular, portable software and LLNL facility that provides an interprocess communication system (IPCS) in the multivendor network. With transparent data access, any program can access data stored anywhere in the network without knowing the specific location. The computer hardware includes a DEC VAX cluster, HP workstations and HP desktop computers. We are using commercial software in addition to packages from MIT, ORNL, and LLNL. 4 refs., 4 figs.

A convenient method for determining the elastic constants of materials has been devised using the energy from a Q-switched neodymium-glass laser. Stress waves are induced in materials having circular rod or rectangular bar geometries by the absorption of energy from the laser. The wave transit times through the material are recorded with a piezoelectric transducer. Both dilatation and shear wave velocities are determined in a single test using an ultrasonic technique and these velocities are used to calculate the elastic constants of the material. A comparison of the constants determined for ten common engineering materials using this method is made with constants derived using the conventional ultrasonic pulse technique and agreement is shown to be about one percent in most cases. Effects of material geometry are discussed and surface damage to the material caused by laser energy absorption is shown.

A neutrino detector at the Brookhaven AGS has been used to investigate the feasibility of using an already constructed apparatus for GUT monopole searches. A flux limit (90%CL) of 5.2 x 10/sup -12/ cm/sup -2/ sec/sup -1/ str/sup -1/ was found. The limitations of such an approach are discussed.

The ECRH diagnostics system monitors the net power delivered to the plasma by four 200-kW gyrotron oscillators, the frequency of each gyrotron, and some operating parameters of the gyrotron power supply system. The combination CAMAC- and GPIB-based data acquisition system is under desktop computer control that provides the capability for data conversion and display. The data acquisition system is also interfaced to the main computer system that acquires and archives the data.

There are new requirements emerging in the field of tomography: the need for spatial resolution in the micrometre range, atomic species specificity, and quantitative density discrimination.

The spacial profile of a bunched or unbunched proton beam may be found by using a highly collimated molecular beam of N/sub 2/. A certain fraction of the molecular N/sub 2/ will be ionized as it crosses the proton beam. By measuring the N/sub 2//sup +/ current as a function of theta the cross section of the beam is directly obtained. As an example, a 10 A proton beam of diameter 1 mm is considered.

Searching for neutrinoless double beta decay is the only known practical method for trying to determine whether neutrinos are their own antiparticles. The theoretical motivation for supposing that they may indeed be their own antiparticles is described. The reason that it is so difficult to ascertain experimentally whether they are or are not is explained, as is the special sensitivity of neutrinoless double beta decay. The potential implications of the observation of this reaction for neutrino mass and for the physics of neutrinos is discussed.

The efficiency of soft x-ray production from laser-irradiated plasmas is simulated for two different spectral regions. These two regions, 14{Angstrom} {plus minus} 15% and 130{Angstrom} {plus minus} 1%, were chosen for proximity mask or point-projection technological applications. Relatively large conversion efficiencies were obtained from irradiation of a stainless steel target using the conditions suggested by recent Hampshire Instruments' experiments for proximity masking. Pulse-width and laser frequency parameter studies were performed for point-projection applications which suggest that the conversion applications which suggest that the conversion efficiency is sensitive to pulse-width but not to laser frequency. One of the critical components of any x-ray lithographic scheme is of course the x-ray laser source. There are two primary contenders for a reliable, efficient source currently: synchrotron radiation and spectral emission from laser produced plasma. The dominant issue for laser-plasma emission is the conversion efficiency -- output in the intended operating spectral region relative the required incident laser energy. Simulations are described in the following for both high and low energy spectral regions which have been suggested by either the proximity masking or point-projection technology.

The Mirror Fusion Test Facility (MFTF) may be upgraded by extending the time of plasma sustenance in an approach to steady-state operation and/or by increasing the neutral-beam injection energy. Some parameter bounds for these upgrades are discussed as they relate to a definition of the required neutral-beam development.

The major objective of this program is to measure thermal rate coefficients and branching ratios of elementary reactions. To perform these measurements, we have constructed an ultrahigh-purity shock tube to generate temperatures between 1000 and 5500 K. The tunable-laser flash-absorption technique is used to measure the rate of change of the concentration of species which absorb below 50,000 cm{sup {minus}1} e.g.: OH, CH, and CH{sub 3}. This technique is being extended into the vacuum-ultraviolet spectral region where we can measure atomic species e.g.: H, D, C, O, and N; and diatomic species e.g.: O{sub 2}, CO, and OH.

Recent measurements of nonsolar isotopic patterns for the elements neon and (perhaps) magnesium in cosmic rays are interpreted within current models of stellar nucleosynthesis. One possible explanation is that the stars currently responsible for cosmic-ray synthesis in the Galaxy are typically super-metal-rich by a factor of two to three. Other possibilities include the selective acceleration of certain zones or masses of supernovas or the enhancement of /sup 22/Ne in the interstellar medium by mass loss from red giant stars and planetary nebulas. Measurements of critical isotopic ratios are suggested to aid in distinguishing among the various possibilities. Some of these explanations place significant constraints on the fraction of cosmic ray nuclei that must be fresh supernova debris and the masses of the supernovas involved. 1 figure, 3 tables.

Article on a preliminary assessment of microbiome changes following blood-feeding and survivorship in the Amblyomma americanum nymph-to-adult transition using semiconductor sequencing.

The group considered physics, accelerator, and polarized source issues. Most of the physics study was concerned with what significant and unique experiments could be done if polarized protons could be accelerated in the main injector and eventually in the Tevatron. 12 refs., 4 figs.

Refined nuclear analysis, including the treatment of resonance and spatial self-shielding, coupled with an optimization procedure, has resulted in improved performance estimates for two conceptual fission-suppressed blankets. Net specific breeding in these two blankets maximized at 0.024 and 0.023 U-233 atoms/MeV, which is about an order of magnitude higher than in fission breeders.

Advanced wave models used to evaluate ICRH in tokamaks typically use warm plasma theory and allow inhomogeneity in one dimension. The majority of these calculations neglect the fact that gyrocenters experience the inhomogeneity via their motion parallel to the magnetic field. The non-local effects of rotational transform and toroidicity can play a significant role in both the propagation and the absorption physics. In strongly driven systems, wave damping can distort the particle distribution function supporting the wave and this produces changes in the absorption. The most common approach is to use Maxwellian absorption rates. We have developed a bounce-averaged Fokker-Planck quasilinear computational model which evolves the population of particles on more realistic orbits. Each wave-particle resonance has its own specific interaction amplitude within any given volume element; these data need only be generated once, and appropriately stored for efficient retrieval. The wave-particle resonant interaction then serves as a mechanism by which the diffusion of particle populations can proceed among neighboring orbits. The local specific spectral energy absorption rate is directly calculable once the orbit geometry and populations are determined. The code is constructed in such fashion as to accommodate wave propagation models which provide the wave spectral energy density on …

Photocathodes of quantum efficiency above 1% at the doubled YAG frequency of 532 nM are very sensitive to the local vacuum environment. These cathodes must have a band gap of less than 2.3 eV, and a work function that is also on the order of {approximately}2 volts or less. As such, these surfaces are very reactive as they provide many surface states for the residual gases that have positive electron affinities such as oxygen and omnipotent water. Attendant to this problem is that the optimal operating point for some of these cesium based cathodes is unstable. Three of the cesium series were tried, the Cs-Ag-Bi-O, the Cs{sub 3}Sb and the K{sub 2}CsSb. The most stable material found is the K{sub 2}CsSb. The vacuum conditions can be met by a variety of pumping schemes. The vacuum is achieved by using sputter ion diode pumps, and baking at 250{degrees}C or less for whatever time is required to reduce the pump currents to below 1 uA at room temperature. To obtain the required partial pressure of cesium, a simple very sensitive diagnostic gauge has been developed that can discriminate between free alkali and other gases present. This Pressure Alkali Monitor (PAM) can be …