Article discussing two different approaches, referred to as renewal and modulation, to generate time series with a nonexponential distribution of waiting times.

Article on chemistry surrounding monomeric copper(I) methyl, phenyl, anilido, ethoxide, and phenoxide complexes supported by N-heterocyclic carbene ligands.

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The galaxy cluster 1E0657-56 (z = 0.296) is remarkably well-suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multi-color, high-resolution HST ACS images allow detection of many more arc candidates than were previously known, especially around the subcluster. Using the known redshift of one of the multiply imaged systems, we determine the remaining source redshifts using the predictive power of the strong lens model. Combining this information with shape measurements of ''weakly'' lensed sources, we derive a high-resolution, absolutely-calibrated mass map, using no assumptions regarding the physical properties of the underlying cluster potential. This map provides the best available quantification of the total mass of the central part of the cluster. We also confirm the result from Clowe et al. (2004, 2006a) that the total mass does not trace the baryonic mass.

We present new weak lensing observations of 1E0657-558 (z = 0.296), a unique cluster merger, that enable a direct detection of dark matter, independent of assumptions regarding the nature of the gravitational force law. Due to the collision of two clusters, the dissipationless stellar component and the fluid-like X-ray emitting plasma are spatially segregated. By using both wide-field ground based images and HST/ACS images of the cluster cores, we create gravitational lensing maps which show that the gravitational potential does not trace the plasma distribution, the dominant baryonic mass component, but rather approximately traces the distribution of galaxies. An 8{sigma} significance spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law, and thus proves that the majority of the matter in the system is unseen.

With the BABAR detector at the PEP-II asymmetric B Factory at SLAC, they present the first search for the decays B{sup 0} {yields} {ell}{sup +}{ell}{sup -}{gamma} ({ell} = e, {mu}). Using a data set of 292 fb{sup -1} collected at the {Upsilon}(4S) resonance, they find no significant signal and set the following branching fraction upper limits at 90% confidence level: {Beta}(B{sup 0} {yields} e{sup +}e{sup -}{gamma}) < 0.7 x 10{sup -7} and {Beta}(B{sup 0} {yields} {mu}{sup +}{mu}{sup -}{gamma}) < 3.4 x 10{sup -7}.

Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

The paper presents the first attempt to estimates the ILC damping ring impedance and compare thresholds of the classical instabilities for several designs initially proposed for the DR. The work was carried out in the spring of 2006. Since then the choice of the DR is narrowed. Nevertheless, the analysis described may be useful for the next iterations of the beam stability. Overall, the conventional instabilities will have little impact on the ring performance provided the careful design of the ring minimizes the impedance below acceptable level indicated above. The only exception is the transverse CB instability. The longitudinal CB is less demanding. However, even the transverse CB instability would have threshold current above nominal provided the aperture in the wigglers is increased from 8 mm to 16 mm. The microwave instability needs more studies. Nevertheless, we should remember that the ILC DR is different from existing high-current machines at least in two respects: absence of the beam-beam tune spread stabilizing beams in colliders, and unusual strict requirements for low emittance. That may cause new problems such as bunch emittance dilution due to high-frequency wakes (BPMs, grooves), etc. Even if such a possibility exists, it probably universal for all machines …

We have studied the spin relaxation in diluted spin ice Ho{sub 2-x} Y{sub x} Ti{sub 2}O{sub 7} by means of neutron spin echo spectroscopy. Remarkably, the geometrical frustration is not relieved by doping with non-magnetic Y, and the dynamics of the freezing is unaltered in the spin echo time window up to x {approx_equal} 1.6. At higher doping with non-magnetic Y (x {ge} 1.6) a new relaxation process at relatively high temperature (up to at least T {approx_equal} 55 K) appears which is more than 10 times faster than the thermally activated main relaxation process. We find evidence that over the whole range of composition all Ho spins participate in the dynamics. These results are compared to a.c. susceptibility measurements of the diluted Ho and Dy spin ice systems. X-ray absorption fine structure (EXAFS) spectra and x-ray diffraction show that the samples are structurally well ordered.

A cement based waste form was evaluated to determine the rates at which various organics were released during heating caused by the cementitious heat-of-hydration reaction. Saltstone is a cement-based waste form for the disposal of low-level salt solution. Samples were prepared with either Isopar{reg_sign} L, a long straight chained hydrocarbon, or (Cs,K) tetraphenylborate, a solid that, upon heating, decomposes to benzene and other aromatic compounds. The saltstone samples were heated over a range of temperatures. Periodically, sample headspaces were purged and the organic constituents were captured on carbon beds and analyzed. Isopar{reg_sign} L was released from the saltstone in a direct relationship to temperature. An equation was developed to correlate the release rate of Isopar{reg_sign} L from the saltstone to the temperature at which the samples were cured. The release of benzene was more complex and relied on both the decomposition of the tetraphenylborate as well as the transport of the manufactured benzene through the curing saltstone. Additional testing with saltstone prepared with different surface area/volume also was performed.

Denitrification can effectively mitigate the problem of high nitrate concentrations in groundwater under dairy operations by reducing nitrate to N{sub 2} gas, at sites where biogeochemical conditions are favorable. We present results from field studies at central California dairies that document the occurrence of saturated-zone denitrification in shallow groundwater using biomolecular indicators, stable isotope compositions of nitrate, and measurements of dissolved excess N{sub 2} gas. Excess N{sub 2} concentrations provide a measure of the extent to which nitrate in groundwater has been partially or completely denitrified. Abundant excess N{sub 2} and young {sup 3}H/{sup 3}He apparent groundwater ages indicate high denitrification rates near manure lagoons where multiple lines of evidence indicate seepage of lagoon water into the groundwater system. Natural tracers of lagoon water include high chloride and dissolved organic carbon concentrations, distinctive trace organic compounds, and high groundwater {delta}{sup 18}O values (relative to other recharge sources). Proximal to the lagoons, NH{sub 4}{sup +} may be present in groundwater, but is strongly adsorbed on to sediment particles. Bubble formation in the lagoons causes the exsolution of other gases (N{sub 2}, Ar, Ne, He, etc.), which partition into the gas phase and strip the lagoon water of its dissolved gas load, …

We discuss optical effects of the wake fields: synchronous phase and bunch length variation along the train of bunches, effect of the wakes on the tune and on the Twiss parameters.

Characterization of the epistemic uncertainty and aleatory variability of ground motion, as part of the Yucca Mountain nuclear waste repository PSHA (Stepp et al., 2001), results in ground motion values that increase without bound as lower and lower annual probabilities of exceedance are considered. For probabilities of exceedance less than about 10{sup -6} (yr{sup -1}), use of these results as input to the site response model leads to ground motion values for the repository that most engineering seismologists feel are not credible. To provide a defensible technical basis to develop credible emplacement level motions for extreme events, the undeformed nature of the 12.8 million year old lithophysal tuff units at Yucca Mountain provide strong constraints on the level of strain (stress) not experienced by the site since deposition of the tuff. Uniaxial unconfined compressive tests (the only tests available to the project) of the lithophysal tuff indicate axial strains of about 0.3% at fracture, which converts to approximately 0.2% shear-strain. This shear-strain limit (fracture strain), which has not occurred, is used with standard equivalent-linear (and nonlinear) point-source site response analyses to develop corresponding response spectra assuming a controlling earthquake of M 6.5 at a distance of 5 km, based on …

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Niobium oxide was deposited reactively using a new type of high-density plasma sputter source. The plasma beam used for sputtering is generated remotely and its path to the target defined by the orthogonal locations of two electromagnets: one at the orifice of the plasma tube and the other just beneath the target plane. To accommodate very large batches of substrates, the trade-off between load capacity and deposition rates was evaluated. The effect on deposition rate was determined by moving the plasma source away from the target in one direction and by moving the target assembly away in an orthogonal direction. A simple methodology was used to reestablish the reactive deposition rate and oxide quality even when large changes were made to the chamber geometry. Deposition parameters were established to produce nonabsorbing niobium oxide films of about 100- and 350-nm thicknesses. The quality of the niobium oxide films was studied spectroscopically, ellipsometrically, and stoichiometrically.

Future high-energy accelerators such as the Next Linear Collider (NLC) will accelerate multi-bunch beams of high current and low emittance to obtain high luminosity, which put stringent requirements on the accelerating structures for efficiency and beam stability. While numerical modeling has been quite standard in accelerator R&D, designing the NLC accelerating structure required a new simulation capability because of the geometric complexity and level of accuracy involved. Under the US DOE Advanced Computing initiatives (first the Grand Challenge and now SciDAC), SLAC has developed a suite of electromagnetic codes based on unstructured grids and utilizing high performance computing to provide an advanced tool for modeling structures at accuracies and scales previously not possible. This paper will discuss the code development and computational science research (e.g. domain decomposition, scalable eigensolvers, adaptive mesh refinement) that have enabled the large-scale simulations needed for meeting the computational challenges posed by the NLC as well as projects such as the PEP-II and RIA. Numerical results will be presented to show how high performance computing has made a qualitative improvement in accelerator structure modeling for these accelerators, either at the component level (single cell optimization), or on the scale of an entire structure (beam heating and …

The aim of this paper is to demonstrate the integration of safety methodology, quality tools, leadership, and teamwork at Hanford and their significant positive impact on safe performance of work. Dashboards, Leading Indicators, Control charts, Pareto Charts, Dr. W. Edward Deming's Red Bead Experiment, and Dr. Deming's System of Profound Knowledge have been the principal tools and theory of an integrated management system. Coupled with involved leadership and teamwork, they have led to significant improvements in worker safety and protection, and environmental restoration at one of the nation's largest nuclear cleanup sites.

We provide a method for obtaining simple models of supersymmetry breaking, with all small mass scales generated dynamically, and illustrate it with explicit examples. We start from models of perturbative supersymmetry breaking, such as O'Raifeartaigh and Fayet models, that would respect an R symmetry if their small input parameters transformed as the superpotential does. By coupling the system to a pure supersymmetric Yang-Mills theory (or a more general supersymmetric gauge theory with dynamically small vacuum expectation values), these parameters are replaced by powers of its dynamical scale in a way that is naturally enforced by the symmetry. We show that supersymmetry breaking in these models may be straightforwardly mediated to the supersymmetric Standard Model, obtain complete models of direct gauge mediation, and comment on related model building strategies that arise in this simple framework.

Reflectivity measurements in the far infrared, performed on aluminum and copper samples, are presented and analyzed. Over a frequency range of interest for the LCLS bunch, the data is fit to the free-electron model, and to one including the anomalous skin effect. The models fit well, yielding parameters dc conductivity and relaxation times that are within 30-40% of expected values. We show that the induced energy in the LCLS undulator region is relatively insensitive to variations on this order, and thus we can have confidence that the wake effect will be close to what is expected.

A Super Flavor Factory, an asymmetric energy e{sup +}e{sup -} collider with a luminosity of order 10{sup 36} cm{sup -2} s{sup -1}, can provide a sensitive probe of new physics in the flavor sector of the Standard Model. The success of the PEP-II and KEKB asymmetric colliders in producing unprecedented luminosity above 10{sup 34} cm{sup -2} s{sup -1} has taught us about the accelerator physics of asymmetric e{sup +}e{sup -} collider in a new parameter regime. Furthermore, the success of the SLAC Linear Collider and the subsequent work on the International Linear Collider allow a new Super-Flavor collider to also incorporate linear collider techniques. This note describes the parameters of an asymmetric Flavor-Factory collider at a luminosity of order 10{sup 36} cm{sup -2} s{sup -1} at the Y(4S) resonance and about 10{sup 35} cm{sup -2} s{sup -1} at the {tau} production threshold. Such a collider would produce an integrated luminosity of about 10,000 fb{sup -1} (10 ab{sup -1}) in a running year (10{sup 7} sec) at the Y(4S) resonance. In the following note only the parameters relative to the Y(4S) resonance will be shown, the ones relative to the lower energy operations are still under study.

We present new measurements of time-dependent CP-violation parameters in hadronic penguin decays: B{sup 0} {yields} K{sup +}K{sup -}K{sub L}{sup 0}, K{sub S}{sup 0}{pi}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0}, {omega}K{sub L}{sup 0}, and a radiative penguin decay B{sup 0} {yields} K{sub S}{sup 0}{pi}{sup 0}{gamma} in a dataset of around 230 {center_dot} 10{sup 6} B{bar B} pairs collected by the BABAR detector at the asymmetric B Factory at SLAC. These CP asymmetry measurements probe for amplitudes beyond the Standard Model in loop-dominated decays of neutral B mesons. While we find a puzzling deviation of CP-asymmetry parameters from predicted values, a full confirmation still awaits more data.

The GaAsP/GaAs strained superlattice photocathode structure has proven to be a significant advance for polarized electron sources operating with high peak currents per microbunch and relatively low duty factor. This is the characteristic type of operation for SLAC and is also planned for the ILC. This superlattice structure was studied at SLAC [1], and an optimum variation was chosen for the final stage of E-158, a high-energy parity violating experiment at SLAC. Following E-158, the polarized source was maintained on standby with the cathode being re-cesiated about once a week while a thermionic gun, which is installed in parallel with the polarized gun, supplied the linac electron beams. However, in the summer of 2005, while the thermionic gun was disabled, the polarized electron source was again used to provide electron beams for the linac. The performance of the photocathode 24 months after its only activation is described and factors making this possible are discussed.

A unique electronics system has been built and tested for reading signals from the silicon-strip detectors of the Gamma-ray Large Area Space Telescope mission. The system amplifies and processes signals from 884,736 36-cm strips using only 160 W of power, and it achieves close to 100% detection efficiency with noise occupancy sufficiently low to allow it to self trigger. The design of the readout system is described, and results are presented from ground-based testing of the completed detector system.

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