Article discussing research on the controllable enhanced dragging of light in ultradispersive media.

Article in the Federal Register, concerning Young Scholars projects, including project development, project environment, project design, activities, the selection of participants, participant costs, project staff, projects site, eligible organizations, budget, proposal preparation and submission, evaluation and selection of proposals, awards, grant administrations, inquiries, program assessment activities, and SST projects.

As Lawrence Livermore National Laboratory moves forward with the design of the National Ignition Facility (NIF) in the Inertial Confinement Fusion (ICF) program, issues relating to the detection and measurement of laser-induced damage on large optics must be addressed. Currently, microscopy is used to evaluate surface quality and measure damage thresholds on small witness samples. In order to evaluate large areas, an automated system was constructed which can scan optics with dimensions as large as 1 meter and weighing as much as 400 pounds. The use of microscopy as the main test diagnostic has been replaced with an optical scatter detection system. Now large areas can be rastered, and maps can be generated, reflecting inherent and laser-induced scatter in multilayer optical coatings and bulk materials. The integrated scattered light from a test piece is measured in transmission using a HeNe laser as the probe source. When the probe beam is overlapped on a pulsed, high power, ND:YAG laser beam, damage related scatter may be measured. This technique has been used for: (1) mapping of inherent scatter in an optic, (2) on-the-fly damage detection during a high fluence raster scan of an optic, and (3) single site damage evaluation for the …

Researchers at the Lawrence Livermore National Laboratory and EG&G Energy Measurements are developing a new solid-state power system for two proposed accelerators. One of the accelerators is a circular arrangement of induction cells called a recirculator. It is designed to accelerate heavy ions for an inertial fusion study that proposes to substitute heavy-ion beams for laser beams as the driver for fusion targets. The other accelerator is a linear induction accelerator for electron beams called the Advanced Radiographic Machine (ARM). Both accelerators require their induction cells to be pulsed at a very high repetition frequency (prf) for a short burst containing 5 to 15 pulses. The recirculator has a pulse schedule that varies in pulse width from 1 {mu}s to 400 ns and in prf from 50 to 150 kHz. The ARM accelerator has a pulse schedule that varies in pulse width from 1 {mu}s to 200 ns and in prf from 150 kHz to 1 MHz. The need for complex pulse agility in these accelerators led the authors to examine solid-state switching components that have an on/off capability. The intrinsic speed of solid-state switching satisfies the high prf requirements, while the on/off switching action of some semiconductor devices enables …

The Department of Energy must demonstrate the effectiveness of the Waste Isolation Pilot Plant (WIPP) as a permanent repository for the disposal of transuranic (TRU) waste. Performance assessments of the WIPP require that estimates of the transportability and outcome of the radionuclides (actinides) be determined from disposal rooms that may become either partially or completely filled with brine. Federal regulations limit the amount of radioactivity that may be unintentionally released to the accessible environment by any mechanism during the post closure phase up to 10,000 years. Thermodynamic models have been developed to predict the concentrations of actinides in the WIPP disposal rooms under various situations and chemical conditions. These models are based on empirical and theoretical projections of the chemistry that might be present in and around the disposal room zone for both near and long-term periods. The actinides that are known to be present in the TRU wastes (and are included in the model) are Th, U, Np, Pu, and Am. Knowledge of the chemistry that might occur in the disposal rooms when the waste comes in contact with brine is important in understanding the range of oxidation states that might be present under different conditions. There is a …

In this paper some of the results of a recent computer search [CoLy99] for optimal three- and four-dimensional lattice rules of specified trigonometric degree are discussed. The theory is presented in a general frame emphasizing the special nature of lattice rules among the rules of specified trigonometric degree.

The authors present the Sequential Access Model (SAM), which is the data handling system for D0, one of two primary High Energy Experiments at Fermilab. During the next several years, the D0 experiment will store a total of about 1 PByte of data, including raw detector data and data processed at various levels. The design of SAM is not specific to the D0 experiment and carries few assumptions about the underlying mass storage level; its ideas are applicable to any sequential data access. By definition, in the sequential access mode a user application needs to process a stream of data, by accessing each data unit exactly once, the order of data units in the stream being irrelevant. The units of data are laid out sequentially in files. The adopted model allows for significant optimizations of system performance, decrease of user file latency and increase of overall throughput. In particular, caching is done with the knowledge of all the files needed in the near future, defined as all the files of the already running or submitted jobs. The bulk of the data is stored in files on tape in the mass storage system (MSS) called Enstore[2] and also developed at Fermilab. …

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Single-shot spectrum measurements of the radiation emitted by an electron bunch provide a novel way to characterize the bunch shape. Shot noise fluctuations in the longitudinal beam density result in radiation with a spectrum that consists of spikes with width inversely proportional to the bunch length. The variance of the Fourier transform of the spectrum is proportional to the convolution function of the beam current averaged over many bunches. After the convolution function is found, the phase retrieval technique can be applied to recover the bunch shape. This technique has been used to analyze the shape of the 4-ps-long bunches at the Low-Energy Undulator Test Line at the Advanced Photon Source.

A new testing strategy is proposed to assess the durability and reliability of non- oxide continuous fiber-reinforced ceramic composites for high temperature structural applications. The strategy is based on determining the reliability (probability of failure) of these materials when subjected to random loading schedules consisting of load and temperature spikes that are superimposed on otherwise constant stress and temperature histories. The frequency and magnitude of the load and temperature spikes would be representative of the number and characteristics of the transients that are associated with a particular industrial application and that are expected to occur over the life of the component. The effect of overstressing on the stress- ruptttre behavior of a CG-NicalonTM fiber-reinforced SiC composite was investigated and results arc presented from tests conducted in ambient air at 950"C.

The superhistory method is incorporated, in different implementations, into two versions of MONK. In this paper the authors intercompare the efficiencies of these implementations via the Figure Of Merit (FOM), and compare the efficiencies of each with that of conventional Monte Carlo (MC). Finally, they suggest preferred versions of MC for eigenvalue calculations. Here, FOM {approx} 1/N{sigma}{sup 2}, where N is the number of histories, and {sigma} is the variance of a quantity of interest. In the criticality-safety version MONK, fission is simulated as suggested in Ref. 1 (Method-1). Every absorption site is a potential fission site, with weight W = {sigma}{sub f}/kx{sigma}{sub a}, where {sigma}{sub f} and {sigma}{sub a} are fission and absorption cross sections, and k is an estimate of the eigenvalue. If W < 1, W is taken as pf, the fission probability. A Method-1 fission produces, on average, {nu} offspring at each site. The reactor-physics MONK uses the standard MC fission treatment (Method-0), i.e. {nu}xW is the average number of neutrons born in a fission, and pf = 1. For consistency, they take absorption sites as potential fission sites in both methods. For v = 1 and a single generation per supergeneration, conventional and superhistory methods …

A single-pass, high-gain free-electron laser (FEL) x-ray amplifier was simulated using the 3D, polychromatic simulation code MEDUSA. The seed for the system is a table-top, soft x-ray laser. The simulated fundamental and nonlinear harmonic x-ray output wavelengths are discussed.

The specifications of presently proposed x-ray free electron lasers (FELs) are for machines that will provide x-ray pulses as short as 100 fs with a photon energy as high as 12.3 keV. Since the pulse will contain as much as 5 mJ of energy, these devices will present the experimenter with an opportunity to expose matter to an unprecedented x-ray energy density. This high concentration of energetic x-rays presents both a promising frontier in energy-matter interaction, as well as a technological crevasse to be crossed by the experimenter attempting to use the FEL beam. The authors shall look at three possible problems confronting the experimenter: (1) synchronization of a detector, laser pulse, etc., to the FEL pulse; (2) radiation damage to the target sample; and (3) the presence of an electromagnetic pulse that could damage sensitive electronics located in the experimental area.

Measurements of self-amplified spontaneous emission (SASE) at 530 nm were made at the Advanced Photon Source (APS) low-energy undulator test line facility (LEUTL). Exponential growth of the optical signal as a function of distance was measured and compared to theoretical estimates. SASE was first observed using a beam generated from a photocathode rf gun system. It was later repeated using beam from a thermonic rf gun system. Following a brief description of the LEUTL facility, they present their results and initial analysis.

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During inspections performed at US nuclear power plants several years ago, some of the prestressed concrete containment had experienced leakage of the tendon sheathing filler. A study was conducted to indicate the extent of the leakage into the concrete and its potential effects on concrete properties. Concrete core samples were obtained from the Trojan Nuclear Plant. Examination and testing of the core samples indicated that the appearance of tendon sheathing filler on the surface was due to leakage of the filler from the conduits and its subsequent migration to the concrete surface through cracks that were present. Migration of the tendon sheathing filler was confined to the cracks with no perceptible movement into the concrete. Results of compressive strength tests indicated that the concrete quality was consistent in the containment and that the strength had increased relative to the strength at 28 days age.

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The authors reviewed the current status of a proposed KAMI (Kaon at Main Injector) experiment at Fermilab to measure the direct CP-violating K{sub L} {r_arrow} {pi}{sup 0}{nu}anti-{nu} decay. Good progress and encouraging results have been made in the past two years for measuring the required photon veto inefficiencies for both CsI and lead-scintillator detectors in a test beam at INS-KEK Japan. New beam test with 150 GeV Main Injector protons has also been scheduled in January 2000 at Fermilab using the existing KTeV detector with two new beam calorimeters. Prospects of a feasible KAMI experiment in the future is discussed here.

The CDF detector at the Tevatron Collider (Fermilab) has collected data from 1992 to 1995. During these years they performed several measurements by using B hadronic decays. All the analysis exploited lepton triggers. The new measurements the authors present here are on radiative B decays B {r_arrow} K{sup 0*} {gamma}, B {r_arrow} {var_phi}{gamma} and {Lambda}{gamma}. They show also preliminary study for the determination of the branching ratios B {r_arrow} J/{psi}K{sup +}{pi}{sup +}{pi}{sup {minus}} and B {r_arrow} {chi}{sub c} (1P) K{sup +}. In view of Run II they discuss CDF reaches using fully reconstructed B hadronic decays. This is done by scaling the number of events and the efficiencies found in Run I without rely on Monte Carlo simulation whenever it is possible.

Demonstration of ultra-high acceleration gradients in the SM LWFA experiments put a next objective for the laser accelerator development to achieve a low-emittance monochromatic acceleration over extended interaction distances. The emerging picosecond terawatt (ps-TW) CO{sub 2} laser technology helps to meet this strategic goal. Among the considered examples are: the staged electron laser accelerator (STELLA) experiment, which is being conducted at the Brookhaven ATF, and the plasma-channeled LWFA. The long-wavelength and high average power capabilities of CO{sub 2} lasers maybe utilized also for generation of intense x-ray and gamma radiation through Compton back-scattering of the laser beams off relativistic electrons. We discuss applications of ps-TW CO{sub 2} lasers for a tentative {gamma}-{gamma} (or {gamma}-lepton) collider and generation of polarized positron beams.

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The STaged ELectron Laser Acceleration (STELLA) experiment will be one of the first to examine the critical issue of staging the laser acceleration process. The BNL inverse free electron laser (EEL) will serve as a prebuncher to generate {approx} 1 {micro}m long microbunches. These microbunches will be accelerated by an inverse Cerenkov acceleration (ICA) stage. A comprehensive model of the STELLA experiment is described. This model includes the EEL prebunching, drift and focusing of the microbunches into the ICA stage, and their subsequent acceleration. The model predictions will be presented including the results of a system error study to determine the sensitivity to uncertainties in various system parameters.

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The technical challenge for making two-beam accelerators into realizable power sources lies in the creation of the drive beam and in its propagation over long distances through multiple extraction sections. This year we have been constructing a 1.2-kA, l-MeV, electron induction prototype injector as a collaborative effort between LBL and LLNL. The electron source will be a 3.5"-diameter, thermionic, flat-surface cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 120-ns flat top (1% energy variation), and a normalized edge emittance of less than 200 {pi}-mm-mr. Planned diagnostics include an isolated cathode with resistive divider for direct measurement of current emission, resistive-wall and magnetic probe current monitors for measuring beam current and centroid position, capacitive probes for measuring A-K gap voltage, an energy spectrometer, and a pepper-pot emittance diagnostic. Details of the injector, beam line, and diagnostics are presented.