[en] BTeV is an approved forward collider experiment at the Fermilab Tevatron dedicated to the precision studies of CP violation, mixing, and rare decays of beauty and charm hadrons. The BTeV detector has been designed to achieve these goals. One of the unique features of BTeV is a state-of-the-art pixel detector system, designed to provide accurate measurements of the decay vertices of heavy flavor hadrons that can be used in the first trigger level. The pixel vertex detector and the trigger design are described. Recent results on some of the achievements in the R and D effort are presented

[en] Precision neutron-induced reaction data are important for modeling the network of isotope production and destruction within a given diagnostic chain. This network modeling has many applications such as the design of advanced fuel cycle for reactors and the interpretation of radiochemical data related to the stockpile stewardship and nuclear forensics projects. Our current funded effort is to improve the neutron-induced reaction data on the short-lived actinides and the specific goal is to improve the neutron capture data on ²³⁸Pu with a half-life of 87.7 years. In this report, the fabrication of a ²³⁸Pu target for the proposed measurement using the DANCE array at LANL is described. The ²³⁸Pu target was fabricated from a sample enriched to 99.35%, acquired from ORNL. A total of 395 (micro)g was electroplated onto both sides of a 3 (micro)m thick Ti foil using a custom-made plating cell, shown in Fig 1. The target-material loaded Ti foil is sandwiched between two double-side aluminized mylar foils with a thickness of 1.4 (micro)m. The mylar foil is glued to a polyimide ring. This arrangement is shown partially in Fig. 2. The assembled target is then inserted into an aluminum container with a wall thickness of 0.76 mm, shown in Fig. 3. A derlin ring is used to keep the target assembly in place. The ends of this cylindrical container are vacuum-sealed by two covers with thin Kapton foils as windows for the beam entrance and exit. Shown in Fig. 4 is details of the arrangement. This target is used for phase I of the proposed measurement on ²³⁸Pu scheduled for Nov 2010 together with the DANCE array to address the safety issues raised by LANL. Shown in Fig. 5 is the preliminary results on the yield spectrum as a function of neutron incident energy with a gate on the total γ-ray energy of equivalent Q value. Since no fission PPAC is employed, the distinction between the capture and fission events cannot be made, which is important for the higher neutron incident energy. However, it indicates that a cross section of less than one barn can be measured. The second phase of this experiment will be carried out in 2011 by assembling a PPAC with the ²³⁸Pu target to extend the measurement to higher neutron incident energies by distinguishing the capture from fission events. The fission cross section becomes dominant for neutron incident energies above 30 keV. This PPAC was developed in FY2010 under the NA22 funding and performed very well for the ²³⁹Pu and ²⁴¹Pu measurements. A new ²³⁸Pu target will be fabricated for the phase II measurement using the same electroplating technique.

[en] We provide a complete solution of closed strings propagating in Nappi-Witten space. Based on the analysis of geodesics we construct the coherent wavefunctions which approximate as closely as possible the classical trajectories. We then present a new free field realization of the current algebra using the gamma, beta ghost system. Finally we construct the quantum vertex operators, for the tachyon, by representing the wavefunctions in terms of the free fields. This allows us to compute the three- and four-point amplitudes, and propose the general result for N-point tachyon scattering amplitude. (author)

[en] As the heating rate of the cold rolled sheets increases in the 0.4% Si electrical steel containing ultra-low carbon, the core loss decreases mainly due to the parabolic grain growth and the magnetic flux density also decreases because of the weakness of the <1 0 0> orientation

[en] Specific computed tomography (CT) findings in four patients with biochemically proven Krabbe disease included symmetric increased attenuation in the cerebellum, brainstem, thalami, caudate nuclei, and corona radiata before and in conjunction with decreased attenuation of white matter followed by atrophy at a later stage. Familiarity with the CT findings in the acute phase of Drabbe disease may assist clinicians in limiting the differential diagnosis and requesting appropriate laboratory tests

[en] Continuing improvements in intravenous DSA techniques have now shown it to be useful in the angiographic evaluation of STA-MCA bypass function. Both patent and non-patent bypasses were observed in this study. Diagnostically adequate spatial resolution and signal to noise ratio were achieved by electronic magnification and integration techniques. Patient positioning was important and the projection which gave optimal visualization of the STA-MCA bypass, free of vessel overlap, was a 40⁰ oblique, 20⁰ craniocaudal view on the side of interest. Intravenous DSA can complement, and in some cases may supplant, conventional arteriography in the radiologic evaluation of STA-MCA bypass surgery. (orig.)

[en] Purpose: To investigate the utility of dual-energy (DE) CT using virtual noncontrast (VNC) and iodine overlay (IO) images to assess therapeutic response to radiofrequency ablation (RFA) for renal cell carcinomas (RCCs). Materials and methods: In this institutional review board-approved study (with waiver of informed consent), 47 patients with RCCs that underwent DECT after RFA were enrolled in this study. DECT protocols included true noncontrast (TNC), linearly blended DE corticomedullary and late nephrographic phase imaging. Two types of VNC and IO images were derived from corticomedullary and late nephrographic phases, respectively. To predict local tumor progression at RFA site, linearly blended and IO images were analyzed both qualitatively and quantitatively. Contrast-to-noise ratios (CNR) of renal cortex-to-RFA zones were calculated. The overall imaging quality of VNC images was compared with TNC images. Results: The IO images from corticomedullary and late nephrographic phases showed excellent diagnostic performance (each sensitivity 100% and each specificity 91.5%) for predicting local tumor progression. The degree of enhancement of local tumor progression was not significantly different between linearly blended and IO images (P > 0.05). The mean CT numbers were not significantly different between TNC and VNC images (P > 0.05). In renal cortex-to-RFA site, CNR between linearly blended and IO images was not significantly different (P > 0.05). The VNC imaging quality from the two phases was given a good rating. Conclusion: VNC and IO images from DECT may allow acceptable diagnostic performance with less radiation exposure as a follow-up imaging tool after RFA for RCC, compared to the linearly blended CT images

[en] A bounce universe model, known as the coupled-scalar-tachyon bounce (CSTB) universe, has been shown to solve the Horizon, Flatness and Homogeneity problems as well as the Big Bang singularity problem. Furthermore a scale invariant spectrum of primordial density perturbations generated from the phase of pre-bounce contraction is shown to be stable against time evolution. In this work we study the detailed dynamics of the bounce and its imprints on the scale invariance of the spectrum. The dynamics of the gravitational interactions near the bounce point may be strongly coupled as the spatial curvature becomes big. There is no a prior reason to expect the spectral index of the primordial perturbations of matter density can be preserved. By encoding the bounce dynamics holographically onto the dynamics of dual Yang-Mills system while the latter is weakly coupled, via the AdS/CFT correspondence, we can safely evolve the spectrum of the cosmic perturbations with full control. In this way we can compare the post-bounce spectrum with the pre-bounce one: in the CSTB model we explicitly show that the spectrum of primordial density perturbations generated in the contraction phase preserves its stability as well as scale invariance throughout the bounce process. (orig.)

[en] Assuming locality, Lorentz invariance and parity conservation we obtain a set of differential equations governing the 3-point interactions of massless bosons, which in turn determines the polynomial ring of these amplitudes. We derive all possible 3-point interactions for tensor fields with polarisations that have total symmetry and mixed symmetry under permutations of Lorentz indices. Constraints on the existence of gauge-invariant cubic vertices for totally symmetric fields are obtained in general spacetime dimensions and are compared with existing results obtained in the covariant and light-cone approaches. Expressing our results in spinor helicity formalism we reproduce the perhaps mysterious mismatch between the covariant approach and the light cone approach in 4 dimensions. Our analysis also shows that there exists a mismatch, in the 3-point gauge invariant amplitudes corresponding to cubic self-interactions, between a scalar field ϕ and an antisymmetric rank-2 tensor field A_μν. Despite the well-known fact that in 4 dimensions rank-2 anti-symmetric fields are dual to scalar fields in free theories, such duality does not extend to interacting theories.

[en] Least squares problems occur frequently in nuclear science including the parameter identification of linear/nonlinear dynamic models, modeling the responses of the spatially distributed detectors, nuclear data treatment, response surface modeling of the thermal margin estimation, etc. Considering the inevitable measurement noise and transport kernel simplification, the ill-posedness of the least squares method can arise and limit the applicability of the assumed model structures. In this paper, a constructive method is proposed with the constrained quadratic programming approach to get the physically meaningful solution. The method is applied to the determination of the parameter vector used to estimate the axially 3-level average core power with ex-core detectors. The test results show the remarkable improvement in accuracy and robustness for the noisy measurement data