Time-resolved photoluminescence spectroscopy has been used to investigate carrier decay dynamics in a In{sub x}Ga{sub 1{minus}x}As{sub 1{minus}y}N{sub y} (x {approximately} 0.03, y {approximately} 0.01) epilayer grown on GaAs by metal organic chemical vapor deposition. Time-resolved photoluminescence (PL) measurements, performed for various excitation intensities and sample temperatures, indicate that the broad PL emission at low temperature is dominated by localized exciton recombination. Lifetimes in the range of 0.07--0.34 ns are measured; these photoluminescence lifetimes are significantly shorter than corresponding values obtained for GaAs. In particular, the authors observe an emission energy dependence of the decay lifetime at 10 K, whereby the lifetime decreases with increasing emission energy across the PL spectrum. This behavior is characteristic of a distribution of localized states, which arises from alloy fluctuations.

A new algorithm compares the background corrected echelle emission image obtained from reference standards to images of unknowns for quantitative elemental analyses. Wavelength was not used in the calculations but instead pixel position and intensity. The data reduction solution was unique to the particular detector/spectrometer. The approach was found useful for several types of images including ICP, DCP and glow discharge images. The analysis scheme required that the emission pattern of standards and background be held in memory. A dual weighting scheme was used that decreased the importance of pixels in high background areas and enhanced the importance of signals from pixels where the standards had emissions. Threshold values were used to limit the calculations to signals in the linear range of the electronics. Logarithmic weighting, (by taking the square root), was found to work well for weighting pixels from the standards. This assured that minor emissions had some influence on the data fit. In the program the best-fit scalar was determined using simple iterative guess, change and test approaches. The test looked for the minimum least square residual value in the areas of the flagged pixels.

The Idaho National Engineering and Environmental Laboratory (INEEL) is aggressively managing waste with no identified path to disposal (WNPD), which was previously termed special case waste (SCW). As a result of several years of this aggressive management, the INEEL has reduced its WNPD volume from approximately 38,000 m{sup 3} in 1993 to approximately 6.33 m{sup 3} in 1999. This paper discusses how the INEEL reduced its WNPD volume. It specifically discusses the beryllium reflector waste produced from the Advanced Test Reactor (ATR) as an example of the INEEL's success in managing its WNPD. The INEEL's success in reducing its WNPD volume is the result of establishing long-range strategic objectives and consistently allocating an annual budget to implement specific work tasks that are consistent with these objectives. In addition, specific short- and long-range work tasks were developed and documented in work control documents. The work tasks are evaluated annually for consistency with the strategic objectives. Since the INEEL has successfully reduced its WNPD volume, it is now focusing on disposing of the remaining volume and preventing future generation of WNPD. As a result of this focused effort, a life-cycle disposal plan was developed for the Advanced Test Reactor (ATR) beryllium waste. …

Small quantities of transuranic (TRU) waste represent a significant challenge to the waste disposition and facility closure plans of several sites in the Department of Energy (DOE) complex. This paper presents the results of a series of evaluations, using a systems engineering approach, to identify the preferred alternative for dispositioning TRU waste from small quantity sites (SQSs). The TRU waste disposition alternatives evaluation used semi-quantitative data provided by the SQSs, potential receiving sites, and the Waste Isolation Pilot Plant (WIPP) to select and recommend candidate sites for waste receipt, interim storage, processing, and preparation for final disposition of contact-handled (CH) and remote-handled (RH) TRU waste. The evaluations of only four of these SQSs resulted in potential savings to the taxpayer of $33 million to $81 million, depending on whether mobile systems could be used to characterize, package, and certify the waste or whether each site would be required to perform this work. Small quantity shipping sites included in the evaluation included the Battelle Columbus Laboratory (BCL), University of Missouri Research Reactor (MURR), Energy Technology Engineering Center (ETEC), and Mound Laboratory. Candidate receiving sites included the Idaho National Engineering and Environmental Laboratory (INEEL), the Savannah River Site (SRS), Los Alamos National …

Between 1992 and 1996 CDF collected about 100 pb{sup {minus}1} of data at a {radical}s = 1.8 TeV at the Fermilab Tevatron collider. This data sample led to a large number of precision measurements of B hadrons properties including their masses, lifetimes and neutral B meson oscillation parameters and the discovery of the B{sub c} meson. Here the author reports on three recent results: the measurement of the B{sup +} production cross section, the search for radiative penguin B hadron decays and the measurement of the CP violating parameter sin 2{beta}. These results are significant examples of the breadth of the CDF program. In 2001 the main injector will allow the Tevatron initially to deliver 1 fb{sup {minus}1} per year at {radical}s = 2 TeV. The CDF detector will undergo major upgrades which will further increase the B physics reach.

One of the legacies of the nuclear weapon and nuclear power cycles has been the generation of large quantities of nuclear waste and fissile materials. As citizens of this planet, it is everyone's responsibility to provide for safe, secure, transparent, disposal of these waste nuclear materials. The Sandia Cooperative Monitoring Center sponsored a Transparency Monitoring Workshop where the use of the Waste Isolation Pilot Plant (WIPP) was identified as a possible transparency demonstration test bed. Three experiments were conceived as jumpstart activities to showcase the effective use of the WIPP infrastructure as a Transparency Demonstration Test Bed. The three experiments were successfully completed and demonstrated at the International Atomic Energy Association sponsored International Conference on Geological Repositories held in Denver Colorado November 1999. The design and coordination of these efforts is the subject of this paper.

Given the advanced state of operational plans for late Run II (132 nsec bunch spacing) the C0 IR insert should be designed to operate such that it does not impact nominal Tevatron parameters. This implies an entirely localized insert -- one which is completely transparent to the rest of the machine. This condition has several important design implications, some of which are pointed out below. An IR design similar to that employed at CDF and D0 is unacceptable as a C0 candidate. The addition of such a (single) low-{beta} region to the machine raises the tune by a half-integer in each plane, moving them far from the standard operating point and right onto the 21.0 integer resonance. The nominal (fractional) operating point is most elegantly maintained by adding 2 local low-{beta} in each plane, thereby boosting the tunes by a full integer. The B0 and D0 IR's are not optically-isolated entities. Progression through the low-{beta}squeeze involves adjusting, not only the main IR quadrupoles, but also the tune quad strings distributed around the ring. The result is that the nominal lattice functions at any point in the ring, and the phase advances across any section of the ring, are not fixed, …

Modest thermal annealing to 600 C of diamondlike amorphous-carbon (a-C) films grown at room temperature results in the formation of carbon nanocomposites with hardness similar to diamond. These nanocomposite films consist of nanometer-sized regions of high density a-C embedded in an a-C matrix with a reduced density of 5--10%. The authors report on the evolution of density and bonding topologies as a function of annealing temperature. Despite a decrease in density, film hardness actually increases {approximately} 15% due to the development of the nanocomposite structure.

As described in contribution AF99-0335, it is interesting that new security services and mechanisms are allowed to be negotiated during a connection in progress. To do that, new ''negotiation OAM cells'' dedicated to security should be defined, as well as some acknowledgment cells allowing negotiation OAM cells to be exchanged reliably. Remarks which were given at the New Orleans meeting regarding those cell formats are taken into account. This contribution presents some baseline text describing the format of the negotiation and acknowledgment cells, and the using of those cells. All the modifications brought to the specifications are reversible using the Word tools.

The nature and origin of lateral composition modulations in (AlAs){sub m}(InAs){sub n} SPSs grown by MBE on InP substrates have been investigated by XRD, AFM, and TEM. Strong modulations were observed for growth temperatures between {approx} 540 and 560 C. The maximum strength of modulations was found for SPS samples with InAs mole fraction x (=n/(n+m)) close to {approx} 0.50 and when n {approx} m {approx} 2. The modulations were suppressed at both high and low values of x. For x >0.52 (global compression) the modulations were along the <100> directions in the (001) growth plane. For x < 0.52 (global tension) the modulations were along the two <310> directions rotated {approx} {+-} 27{degree} from [110] in the growth plane. The remarkably constant wavelength of the modulations, between {approx} 20--30 nm, and the different modulation directions observed, suggest that the origin of the modulations is due to surface roughening associated with the high misfit between the individual SPS layers and the InP substrate. Highly uniform unidirectional modulations have been grown, by control of the InAs mole fraction and growth on suitably offcut substrates, which show great promise for application in device structures.

A gridless technique for the solution of the integral form of the radiative heat flux equation for emitting and absorbing media is presented. Treatment of non-uniform absorptivity and gray boundaries is included. As part of this work, the authors have developed fast multipole techniques for extracting radiative heat flux quantities from the temperature fields of one-dimensional and three-dimensional geometries. Example calculations include those for one-dimensional radiative heat transfer through multiple flame sheets, a three-dimensional enclosure with black walls, and an axisymmetric enclosure with black walls.

Secretary of Energy, Bill Richardson, has stated that one of the nuclear waste legacy issues is ``The challenge of managing the fuel cycle's back end and assuring the safe use of nuclear power.'' Waste management (i.e., the back end) is a domestic and international issue that must be addressed. A key tool in gaining acceptance of nuclear waste repository technologies is transparency. Transparency provides information to outside parties for independent assessment of safety, security, and legitimate use of materials. Transparency is a combination of technologies and processes that apply to all elements of the development, operation, and closure of a repository system. A test bed for nuclear repository transparency technologies has been proposed to develop a broad-based set of concepts and strategies for transparency monitoring of nuclear materials at the back end of the fuel/weapons cycle. WIPP is the world's first complete geologic repository system for nuclear materials at the back end of the cycle. While it is understood that WIPP does not currently require this type of transparency, this repository has been proposed as realistic demonstration site to generate and test ideas, methods, and technologies about what transparency may entail at the back end of the nuclear materials cycle, …

Recent data from the CDF and D0 experiments at the Tevatron are presented on b quark production cross sections, J/{psi}, {psi}{prime} and {Upsilon} production cross sections. An analysis from CDF of the production polarization of the J/{psi}, {psi}{prime} and {Upsilon}(1S) is reviewed and the results discussed in the context of the color octet model.

Groundwater monitoring has detected tritium ({sup 3}H) and {sup 22}Na contamination down gradient from the Brookhaven LINAC Isotope Producer (BLIP), located at Brookhaven National Laboratory (BNL). Site characterization studies indicate that the BLIP is the source of contamination. The highest measured values for {sup 3}H were 52,400 pCi/L recorded less than 100 feet south (down gradient) of the BLIP facility. The BLIP produces radioisotopes that are crucial in nuclear medicine for both research and clinical use. The BLIP also supports research on diagnostic and therapeutic radiopharmaceuticals. During operation a proton beam impinges a target (typically salts encapsulated in stainless steel) to produce the required radioisotopes. The proton beam is completely absorbed prior to reaching the soils surrounding the target shaft. However, secondary neutrons are produced that reach the soil causing activation products to form. Among the longer-lived isotopes of concern are tritium and {sup 22}Na. Both of these isotopes have the potential to negatively impact the groundwater below the BLIP. Several corrective actions have been implemented at the BLIP facility in response to tritium detection in the groundwater. The first actions were to improve surface water management (e.g. storm water down spouts) and the installation of a gunite cap around …

The authors study multi-photon-assisted transmission of electrons through single-step, single-barrier and double-barrier potential-energy structures as a function of the photon energy and the temperature. Sharp resonances in the spectra of the tunneling current through double-barrier structures are relevant to infra-red detectors.

The switching and memory retention time has been measured in 50 {micro}m gatelength pseudo-non-volatile memory MOSFETs containing, protonated 40 nm gate oxides. Times of the order of 3.3 seconds are observed for fields of 3 MV cm{sup {minus}1}. The retention time with protons placed either at the gate oxide/substrate or gate oxide/gate electrode interfaces is found to better than 96% after 5,000 seconds. Measurement of the time dependence of the source-drain current during switching provides clear evidence for the presence of dispersive proton transport through the gate oxide.

Polarized magneto-photoluminescence (MPL) measurements on a high mobility {delta}-doped GaAs/AlGaAs single quantum well from 0--60 T at temperatures between 0.37--2.1 K are reported. In addition to the neutral heavy hole magneto-exciton (X{sup 0}), the singlet (X {sub s}{sup {minus}}) and triplet (X {sub t}{sup {minus}}) states of the negatively charged magneto-exciton are observed in both polarizations. The energy dispersive and time-resolved MPL data suggest that their development is fundamentally related to the formation of the neutral magneto-exciton. At a magnetic field of 40 T the singlet and the triplet states cross as a result of the role played by the higher Landau levels and higher energy subbands in their energetic evolution, confirming theoretical predictions. The authors also observed the formation of two higher energy peaks. One of them is completely right circularly polarized and its appearance can be considered a result of the electron-hole exchange interaction enhancement with an associated electron g-factor of 3.7 times the bulk value. The other peak completely dominates the MPL spectrum at fields around 30 T. Its behavior with magnetic field and temperature indicates that it may be related to previous anomalies observed in the integer and fractional quantum Hall regimes.

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As Linux clusters have matured as platforms for low-cost, high-performance parallel computing, software packages to provide many key services have emerged, especially in areas such as message passing and net-working. One area devoid of support, however, has been parallel file systems, which are critical for high-performance I/O on such clusters. We have developed a parallel file system for Linux clusters, called the Parallel Virtual File System (PVFS). PVFS is intended both as a high-performance parallel file system that anyone can download and use and as a tool for pursuing further research in parallel I/O and parallel file systems for Linux clusters. In this paper, we describe the design and implementation of PVFS and present performance results on the Chiba City cluster at Argonne. We provide performance results for a workload of concurrent reads and writes for various numbers of compute nodes, I/O nodes, and I/O request sizes. We also present performance results for MPI-IO on PVFS, both for a concurrent read/write workload and for the BTIO benchmark. We compare the I/O performance when using a Myrinet network versus a fast-ethernet network for I/O-related communication in PVFS. We obtained read and write bandwidths as high as 700 Mbytes/sec with Myrinet and …

Engineers at the Idaho National Engineering and Environmental Laboratory (INEEL) are investigating the use of a proprietary silicon-polymer to encapsulate high-level calcine waste stored at the INEEL's Idaho Nuclear Technology and Engineering Center (INTEC). The silicon-polymer-encapsulated waste may be suitable for direct disposal at a radioactive waste disposal facility or for transport to an offsite melter for further processing. In connection with silicon-polymer encapsulation, the University of Akron, under special arrangement with Orbit Technologies, the originator of the Polymer Encapsulation Technology (PET), has studied a simulated waste material from INTEC called pilot-scale calcine that contains hazardous materials but no radioactive isotopes. In this study, Toxicity Characteristic Leaching Procedure (TCLP) and Materials Characterization Center Test 1P were performed to test the waste form for disposal. In addition, a maximum waste loading was established for transporting the calcine waste at INTEC to an offsite melter. For this maximum waste loading, compressive strength testing, 10-m drop testing, melt testing, and a Department of Transportation (DOT) oxidizer test were performed.

The Authenticated Tracking and Monitoring System (ATMS) is designed to answer the need for global monitoring of the status and location of proliferation-sensitive items on a worldwide basis, 24 hours a day. ATMS uses wireless sensor packs to monitor the status of the items within the shipment and surrounding environmental conditions. Receiver and processing units collect a variety of sensor event data that is integrated with GPS tracking data. The collected data are transmitted to the International Maritime Satellite (INMARSAT) communication system, which then sends the data to mobile ground stations. Authentication and encryption algorithms secure the data during communication activities. A typical ATMS application would be to track and monitor the stiety and security of a number of items in transit along a scheduled shipping route. The resulting tracking, timing, and status information could then be processed to ensure compliance with various agreements.

Nanostructural characterization of amorphous diamondlike carbon (a-C) films grown on silicon using pulsed-laser deposition (PLD) is correlated to both growth energetic and film thickness. Raman spectroscopy and x-ray reflectivity probe both the topological nature of 3- and 4-fold coordinated carbon atom bonding and the topographical clustering of their distributions within a given film. In general, increasing the energetic of PLD growth results in films becoming more ``diamondlike'', i.e. increasing mass density and decreasing optical absorbance. However, these same properties decrease appreciably with thickness. The topology of carbon atom bonding is different for material near the substrate interface compared to material within the bulk portion of an a-C film. A simple model balancing the energy of residual stress and the free energies of resulting carbon topologies is proposed to provide an explanation of the evolution of topographical bonding clusters in a growing a-C film.

This paper addresses the work that SRTC is performing in the design, fabrication, assembly, and testing of the TRU-Waste Repackaging Module.

Polycrystalline Sr{sub 3}Mn{sub 2}O{sub 6.54} and Sr{sub 3}Mn{sub 2}O{sub 7} layered manganites were studied at room temperature using Raman spectroscopy. While the phonon spectrum of the stoichiometric Sr{sub 3}Mn{sub 2}O{sub 7} sample is consistent with the group theoretical analysis for the 14/mm structure, three additional modes are observed in the phonon spectrum of the oxygen deficient Sr{sub 3}Mn{sub 2}O{sub 6.54} sample. Based on an analysis of the temperature dependence of the Raman spectrum of Sr{sub 3}Mn{sub 2}O{sub 6.54} and a comparison with the Raman spectrum of LaSr{sub 2}Mn{sub 2}O{sub 7}, the authors conclude that the extra modes should be viewed as disorder induced Raman scattering.