This paper reports on experiments aimed at developing a new high-intensity H{sup -} ion source with long lifetime whose concept had recently been introduced. Starting from the motivation for this effort, several steps of the earlier development work are recapitulated, and the performance of the latest design variant is discussed in detail. The basic concept consists in coupling an ECR ion source to a standard SNS multi-cusp H{sup -} ion source that is driven by pulsed dc, rather than rf, power. As a key result, an electron beam of 1.5 A current has been extracted from the ECR discharge operating at 1.9 kW c. w. power, and a maximum discharge current of 17.5 A was achieved in the H{sup -} ion source. Production of H{sup -} ions, however could not yet been demonstrated in the one, preliminary, experiment conducted so far. The paper concludes by outlining further envisaged development steps for the plasma generator and an expansion towards a novel extraction system.

Collecting debris samples following a nuclear event requires that operations be conducted from a considerable stand-off distance. An ultra-wide range gamma detector system has been constructed to accomplish both long range radiation search and close range hot sample collection functions. Constructed and tested on a REMOTEC Andros platform, the system has demonstrated reliable operation over six orders of magnitude of gamma dose from 100's of uR/hr to over 100 R/hr. Functional elements include a remotely controlled variable collimator assembly, a NaI(Tl)/photomultiplier tube detector, a proprietary digital radiation instrument, a coaxially mounted video camera, a digital compass, and both local and remote control computers with a user interface designed for long range operations. Long range sensitivity and target location, as well as close range sample selection performance are presented.

We compare several different parallel implementation approaches for the clustering operations performed during adaptive gridding operations in patch-based structured adaptive mesh refinement (SAMR) applications. Specifically, we target the clustering algorithm of Berger and Rigoutsos (BR91), which is commonly used in many SAMR applications. The baseline for comparison is a simplistic parallel extension of the original algorithm that works well for up to O(10{sup 2}) processors. Our goal is a clustering algorithm for machines of up to O(10{sup 5}) processors, such as the 64K-processor IBM BlueGene/Light system. We first present an algorithm that avoids the unneeded communications of the simplistic approach to improve the clustering speed by up to an order of magnitude. We then present a new task-parallel implementation to further reduce communication wait time, adding another order of magnitude of improvement. The new algorithms also exhibit more favorable scaling behavior for our test problems. Performance is evaluated on a number of large scale parallel computer systems, including a 16K-processor BlueGene/Light system.

The authors report a search for the decays B{sup 0} {yields} D{sub s}{sup -}D{sub s}{sup +}, B{sup 0} {yields} D*{sub s}{sup -}D{sub s}{sup +} and B{sup 0} {yields} D*{sub s}{sup -}D*{sub s}{sup +} in a sample of 232 million {Upsilon}(4S) decays to B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring. They find no significant signal and set upper bounds for the branching fractions: {Beta}(B{sup 0} {yields} D{sub s}{sup -}D{sub s}{sup +}) < 1.0 x 10{sup -4}, {Beta}(B{sup 0} {yields} D*{sub s}{sup -} D{sub s}{sup +}) < 1.3 x 10{sup -4} and {Beta}(B{sup 0} {yields} D*{sub s}{sup -} D*{sub s}{sup +}) < 2.4 x 10{sup -4} at 90% confidence level.

We present preliminary results of maximum-likelihood Dalitz plot analyses performed by the BABAR Collaboration of the charmless hadronic decays B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0}, B{sup +} {yields} K{sup +}{pi}{sup -}{pi}{sup +}, and B{sup +} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup +}. We report inclusive decay rates, as well as fractions and phases for intermediate resonant decays.We also report CP-violating charge asymmetries for intermediate resonant decays of neutral B mesons.

The light-front quantization of gauge theories in light-cone gauge provides a frame-independent wavefunction representation of relativistic bound states, simple forms for current matrix elements, explicit unitarity, and a Fock space built on a trivial vacuum. The AdS/CFT correspondence has led to important insights into the properties of quantum chromodynamics even though QCD is a broken conformal theory. We have recently shown how a model based on a truncated AdS space can be used to obtain the hadronic spectrum of q{bar q}, qqq and gg bound states, as well as their respective light-front wavefunctions. Specific hadrons are identified by the correspondence of string modes with the dimension of the interpolating operator of the hadron's valence Fock state, including orbital angular momentum excitations. The predicted mass spectrum is linear M {proportional_to} L at high orbital angular momentum, in contrast to the quadratic dependence M{sup 2}/L found in the description of spinning strings. Since only one parameter, the QCD scale {Lambda}{sub QCD}, is introduced, the agreement with the pattern of physical states is remarkable. In particular, the ratio of {Delta} to nucleon trajectories is determined by the ratio of zeros of Bessel functions. As a specific application of QCD dynamics from AdS/CFT duality, …

We present the first results from a very deep Chandra X-ray observation of the core of the Perseus cluster of galaxies. A pressure map reveals a clear thick band of high pressure around the inner radio bubbles. The gas in the band must be expanding outward and the sharp front to it is identified as a shock front, yet we see no temperature jump across it; indeed there is more soft emission behind the shock than in front of it. We conclude that in this inner region either thermal conduction operates efficiently or the co-existing relativistic plasma seen as the radio mini-halo is mediating the shock. If common, isothermal shocks in cluster cores mean that we cannot diagnose the expansion speed of radio bubbles from temperature measurements alone. They can at times expand more rapidly than currently assumed without producing significant regions of hot gas. Bubbles may also be significantly more energetic. The pressure ripples found in earlier images are identified as isothermal sound waves. A simple estimate based on their amplitude confirms that they can be an effective distributed heat source able to balance radiative cooling.We see multiphase gas with about 10{sup 9}M{sub {circle_dot}} at a temperature of about …

A matrix formalism is developed to describe the spin dynamics in a synchrotron near a single depolarization resonance as the particle energy (and therefore its spin precession frequency) is varied in a prescribed pattern as a function of time such as during acceleration. This formalism is first applied to the case of crossing the resonance with a constant crossing speed and a finite total step size, and then applied also to other more involved cases when the single resonance is crossed repeatedly in a prescribed manner consisting of linear ramping segments or sudden jumps. How repeated crossings produce an interference behavior is discussed using the results obtained. For a polarized beam with finite energy spread, a spin echo experiment is suggested to explore this interference effect.

The BaBar experiment at SLAC is designed to measure CP violation in the B meson system, however the very high statistics combined with the different e{sup +} and e{sup -} beam energies, the detector design and the open trigger allow a wide variety of spectroscopic measurements. We are beginning to tap this potential via several production mechanisms. Here we present recent results from initial state radiation, hadronic jets, few body B and D hadron decays, and interactions in the detector material. We also summarize measurements relevant to D{sub s} meson spectroscopy, pentaquarks and charmonium spectroscopy from multiple production mechanisms.

The recent rise of ''computer-assisted'' and ''experimental'' mathematics raises intriguing questions as to the future role of computation in mathematics. These results also draw into question the traditional distinctions that have been drawn between formal proof and computationally-assisted proof. This article explores these questions in the context of the growing consensus among computer technologists that Moore's Law is likely to continue unabated for quite some time into the future, producing hardware and software much more powerful than what is available today.

UmuD{sub 2} cleaves and removes its N-terminal 24 amino acids to form UmuD'{sub 2}, which activates UmuC for its role in UV-induced mutagenesis in E. coli. Cells with a non-cleavable UmuD exhibit essentially no UV-induced mutagenesis and are hypersensitive to killing by UV light. UmuD has been shown to bind to the beta processivity clamp (''beta'') of the replicative DNA polymerase, pol III. A possible beta-binding motif has been predicted in the same region of UmuD shown to be important for its interaction with beta. We performed alanine-scanning mutagenesis of this motif (14-TFPLF-18) in UmuD and showed that it has a moderate influence on UV-induced mutagenesis but is required for the cold sensitive phenotype caused by elevated levels of wild-type UmuD and UmuC. Surprisingly, the wild-type and the beta-binding motif variant bind to beta with similar K{sub d} values as determined by changes in tryptophan fluorescence. However, this data also implies that the single tryptophan in beta is in strikingly different environments in the presence of the wild-type versus the variant UmuD proteins, suggesting a distinct change in some aspect of the interaction with little change in its strength. Despite the fact that this novel UmuD variant is noncleavable, we …