Article on the strain effects on the interface properties of nitride semiconductors.

Article on the theory of surface morphology of wurtzite GaN (0001) surfaces.

None

None

None

We have measured the flavor ratio of ratios (R) in atmospheric neutrino interactions using a 1.52 kton-year exposure of Soudan 2. We find R = 0.67 {+-} 0.15{sub {minus}0.06}{sup +0.04}. This value is about 2{sigma} from the expected value of 1.0 and is consistent with the anomalous ratios measured by the Kamiokande and IMB experiments. We note that since our acceptance matrix is different from those of the water Cherenkov experiments we would not expect to measure the same value of R, unless R=1.

Several authors have presented models for neutrino production from Active Galactic Nuclei (AGN) that allow for the possibility of AGN neutrinos outnumbering the atmospheric neutrino flux for energies in excess of 30 TeV. The authors present preliminary results from a search for high energy neutrinos from AGN using the underground Soudan 2 Detector.

Article commenting on an article titled, "Retention of Ionizable Compounds on HPLC. pH Scale in Methanol-Water and the pK and pH Values of Buffers."

The evolution of the Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities in the nonlinear regime of growth was investigated in indirect-drive experiments on the Nova laser. The RT experiments investigated the evolution of both single- and multimode perturbations at an embedded interface, isolated from the effects of ablation. This ``classical`` geometry allows short wavelength ({lambda} {approximately} 10-20 {micro}m) perturbations to grow strongly, in marked contrast to prior results at an ablation front. The RM experiments studied singly- and doubly-shocked perturbed interfaces in both face-on and side-on geometries. (U)

Inelastic neutron scattering measurements across the TSDW satellites of chromium were performed at {Delta}E=5,20meV, both under zero field and 5T magnetic field. Analysis concerning the transverse magnetic excitations (T{sub 1},T{sub 2}) and the longitudinal magnetic excitations (L) indicates that T{sub 1} and L are equally intense while T{sub 2} dominates and becomes more so at higher energies.

A measurement of the two-particle correlation of identified pions was performed in the E802/E859 magnetic spectrometer on the interval 1.5 {le} y {le} 2.0, {delta}{phi} = 0.4 rad, for central {sup 28}Si + Au collisions. It is demonstrated that the two-pion correlation in rapidity is entirely due to Bose-Einstein interference. The directly measured exponential correlation length is {zeta}{sub y} = 0.20 {+-} 0.03 for two {pi}{sup {minus}}, with strength R(0,0) {approximately} 1%, in agreement with previous E802 indirect measurements derived from an analysis of intermittency using Negative Binomial Distributions.

The unusual metal SrRuO{sub 3} is perhaps the only known 4d transition metal based ferromagnet (Tc = 162K) with a sizable moment. To complement low T polarized neutron diffraction measurements of the magnetization density, high T neutron diffraction measurements are reported here. Two structural phase transitions are observed. Between 10K and 800K SrRuO{sub 3} is orthorhombic and at 800K it appears to be tetragonal until 975K, where it becomes cubic. The temperature variation of the lattice parameters are reported along with a structural description of the tetragonal phase.

MCNP4B was released in early 1997. In this new version, several major changes were made to the underlying theory used to estimate the non-adjoint-weighted removal, fission, capture, and escape prompt-neutron lifetimes. These four lifetimes are now being calculated in accordance to the neutron-balance theory described by Spriggs et al. in which the non-adjoint-weighted lifetime for a particular type of reaction (i.e., fission, capture, escape, removal, etc.) is defined as the total neutron population in the system divided by that reaction rate.

The Wide-Angle Neutron Diffractometer (WAND) is a flat-cone geometry diffractometer located at the High Flux Reactor (HFIR). This instrument is currently being upgraded. The central part of this upgrade is the development of a new curved one-dimensional position sensitive detector which covers a 125 degree angular range with an effective radius of 71 cm. This detector will be a multi-anode (624 anodes on a 0.2 degree pitch) {sup 3}He gas-filled proportional counter. This totally new system will give high resolution, good uniformity and high counting range - a maximum capability of 10{sup 5} cps/pixel and a 10{sup 7} cps overall. A prototype of this detector has shown that these design targets can be met. The new WAND will greatly broaden its capabilities for single-crystal diffraction experiments and for time-resolved measurements.

This paper describes three key processes used in deactivating the Plutonium Uranium Extraction (PUREX) Facility, a large, complex nuclear reprocessing facility, 15 months ahead of schedule and $77 million under budget. The organization was reengineered to refine its business processes and more effectively organize around the deactivation work scope. Multi-disciplined work teams were formed to be self-sufficient and empowered to make decisions and perform work. A number of benefits were realized by reengineering. A comprehensive process to develop end points which clearly identified specific results and the post-project facility configuration was developed so all areas of a facility were addressed. Clear and specific end points allowed teams to focus on completing deactivation activities and helped ensure there were no unfulfilled end-of-project expectations. The RCRA regulations require closure of permitted facilities within 180 days after cessation of operations which may essentially necessitate decommissioning. A more cost effective approach was adopted which significantly reduced risk to human health and the environment by taking the facility to a passive, safe, inexpensive-to-maintain surveillance and maintenance condition (deactivation) prior to disposition. PUREX thus became the first large reprocessing facility with active TSD [treatment, storage, and disposal] units to be deactivated under the RCRA regulations.

Development of a worldwide network to monitor seismic activity requires deployment of seismic sensors in areas which have not been well studied or may have from available recordings. Development and testing of detection and discrimination algorithms requires a robust representative set of calibrated seismic events for a given region. Utilizing events with poor signal-to-noise (SNR) can add significant numbers to usable data sets, but these events must first be adequately filtered. Source and path effects can make this a difficult task as filtering demands are highly varied as a function of distance, event magnitude, bearing, depth etc. For a given region, conventional methods of filter selection can be quite subjective and may require intensive analysis of many events. In addition, filter parameters are often overly generalized or contain complicated switching. We have developed a method to provide an optimized filter for any regional or teleseismically recorded event. Recorded seismic signals contain arrival energy which is localized in frequency and time. Localized temporal signals whose frequency content is different from the frequency content of the pre-arrival record are identified using rms power measurements. The method is based on the decomposition of a time series into a set of time series signals …

An automated leak test system for tritium shipping containers has been developed at Westinghouse Savannah River Co. (WSRC). The leak detection system employs a computer controlled helium detector which allows an operator to enter key information when prompted. The software for controlling the tests and the equipment apparatus were both designed and manufactured at the Savannah River Technology Center within WSRC. Recertification Test: Every twelve months, the pressure vessel portion of the shipping container itself must undergo a rigorous recertification leak test. After an empty pressure vessel (shipping container) is assembled, it is placed into one of six stainless steel belljars for helium leak testing. The belljars are fashioned in row much the same as assembly line arrangement. Post-load Test: A post-load leak test is performed upon reservoirs that have been filled with tritium and placed inside the shipping containers mentioned above. These leak tests are performed by a rate-of-rise method where the area around the shipping container seals is evacuated, valved off from the vacuum pump, and then the vacuum pressure is monitored over a two-minute period. The Post Load Leak Test is a quality verification test to ensure that the shipping container has been correctly assembled. 2 figs.

Nuclear fission power reactors represent a solution-in-principle to all aspects of global change possibly induced by inputting of either particulate or carbon or sulfur oxides into the Earth`s atmosphere. Of proven technological feasibility, they presently produce high- grade heat for electricity generation, space heating and industrial process-driving around the world, without emitting greenhouse gases or atmospheric particulates. However, a substantial number of major issues currently stand between nuclear power implemented with light- water reactors and widespread substitution for large stationary fossil fuel-fired systems, including long-term fuel supply, adverse public perceptions regarding both long-term and acute operational safety, plant decommissioning, fuel reprocessing, radwaste disposal, fissile materials diversion to military purposes and - perhaps more seriously - cost. We describe a GW-scale, high-temperature nuclear reactor heat source that can operate with no human intervention for a few decades and that may be widely acceptable, since its safety features are simple, inexpensive and easily understood. We provide first-level details of a reactor system designed to satisfy these requirements. Such a back-solving approach to realizing large-scale nuclear fission power systems potentially leads to an energy source capable of meeting all large-scale stationary demands for high- temperature heat. If widely employed to support such demands, …

Traditionally, pollution prevention (P2) assessments have been performed on existing facilities and ongoing operations, well after the completion of design and construction. It has been theorized that more success can be achieved by moving P2 upstream into the design process, where an estimated 70% of a project`s total life cycle costs are initially fixed. Decisions made during design to prevent or minimize the amount of waste generated can reap benefits for many years to come. This is especially true when designing systems for handling hazardous and radioactive wastes for treatment, storage, and disposal. P2 assessments performed during design of such projects can uncover significant savings to be reaped during project construction, operations, and/or decommissioning. However, many project managers are still reluctant to include some type of P2 review or assessment as part of the design effort, because the immediate payback to the design entity is difficult to quantify. This paper presents the results of a P2 assessment performed on a design project at Hanford which identified close to $500,000 in construction savings while minimizing low-level and mixed radioactive waste generation. This paper describes the process used to per-form the assessment, discusses its results, and provides lessons-learned for future P2 design …

Some issues of control in complex dynamical systems are considered. The authors discuss two control mechanisms, namely: a short range, reactive control based on the chaos control idea and a long-term strategic control based on an optimal control algorithm. They apply these control ideas to simple examples in a discrete nonlinear model of a multi-nation arms race.

Approximately 15% of the Low Level Waste (LLW) produced at Los Alamos consists of scrap metal equipment and materials. The majority of this material is produced by decommissioning and modification of existing facilities. To address this waste stream, Los Alamos has developed a scrap metal recycling program that is operated by the Environmental Stewardship Office to minimize the amount of LLW metal sent for LLW landfill disposal. Past practice has supported treating all waste metals generated within RCA`s as contaminated. Through the metal recycling project, ESO is encouraging the use of alternatives to LLW disposal. Diverting RSM from waste landfill, disposal protects the environment, reduces the cost of operation, and reduces the cost of maintenance and operation at landfill sites. Waste minimization efforts also results in a twofold economic reward: The RSM has a market value and decontamination reduces the volume and therefore the amount of the radioactive waste to be buried within landfills.

We show that the conventionally defined partonic cross section for the production of isolated prompt photons is not an infrared safe quantity. We work out the case of e{sup +}e{sup -} {yields} {gamma} + X in detail, and we discuss implications for hadron reactions such as p{bar p} {yields} {gamma} + X.

The authors investigate the flow patterns in a cylindrical rotating Rayleigh-Benard convection cell with radius-to-height ratio {Gamma} = 0.5. The Rayleigh number R is 2 x 10{sup 8}, the dimensionless rotation rate {Omega} varies from 10{sup 4} to 5 x 10{sup 4}, and the convective Rossby number Ro is between 2 and 0.4. Measurements of the velocity field in the volume adjacent to the top of the cell are acquired with a scanning particle image velocimetry (PIV) system. The authors present quantitative results for velocity and vorticity of the cyclonic and anticyclonic vortices characterizing the convection, as well as for the dependence of the vortex size on the rotation rate and variation of vorticity with depth.

THis report presents preliminary results from a large scale study of surface wave group velocity dispersion throughout Northern Africa, the Mediterranean, Southern Europe and the Middle East. Our goal is to better define the 3D lithospheric shear-wave velocity structure within this region by improving the resolution of global surface wave tomographic studies. We hope to accomplish this goal by incorporating regional data at relatively short periods (less than 40 sec), into the regionalization of lateral velocity variation. Due to the sparse distributions of stations and earthquakes throughout the region (Figure 1) we have relied on data recorded at both teleseismic and regions; distances. Also, to date we have concentrated on Rayleigh wave group velocity measurements since valuable measurements can be made without knowledge of the source. In order to obtain Rayleigh wave group velocity throughout the region, vertical component teleseismic and regional seismograms were gathered from broadband, 3-component, digital MEDNET, GEOSCOPE and IRIS stations plus the portable PASSCAL deployment in Saudi Arabia. Figure 1 shows the distribution of earthquakes (black circles) and broadband digital seismic stations (white triangles) throughout southern Europe, the middle east and northern Africa used in this study. The most seismicly active regions of northern Africa are …