Parity violating pion electroproduction off the nucleon

Parity violating (PV) contributions due to interference between $\gamma$ and $Z^0$ exchange are calculated for pion electroproduction off the nucleon. A phenomenological model with effective Lagrangians is used to determine the resulting asymmetry for the energy region between threshold and $\Delta(1232)$ resonance. The $\Delta$ resonance is treated as a Rarita-Schwinger field with phenomenological $N \Delta$ transition currents. The background contributions are given by the usual Born terms using the pseudovector $\pi N$ Lagrangian. Numerical results for the asymmetry are presented.Comment: 17 pages, RevTeX, 6 figures (in separate file figs.uu), uses epsf, accepted for publication in Z. Phys.

Structural And Magnetic Study Of Labacocu O5+δ

The structure and magnetic properties of the compound LaBaCuCo O5+δ have been studied for the non-stoichiometric oxygen concentration δ≈0.6. The structure is pseudo-cubic with a tripled perovskite unit cell. The crystal structure was determined by a combined Rietveld fit to neutron and synchrotron x-ray powder diffraction data in the orthorhombic Pmmm space group, with cell parameters a=3.9223 (3) Å, b=3.9360 (3) Å, c=11.7073 (8) Å, and V=180.74 (2) Å3 (room temperature). Antiferromagnetic ordering of Cu and Co magnetic moments is observed below 205 (4) K. The magnetic structure with cell aM =2a, bM =2b, and cM =2c, could be described with the Shubnikov space group Fmm m′. The magnetic moments of both equivalent Cu/Co sites were determined at 50 and 170 K to be 0.83 (3) μB and 0.58 (3) μB, respectively, consistent with one unpaired electron per atom. The fit of the intensities to a simple mean field magnetic model appeared to be insufficient to account for the variation of moments at temperatures close to TN while a three dimensional Heisenberg model could improve the fit. Susceptibility measurements between 4 and 350 K also show irreversibility below 150 K. The local environments of Cu and Co were studied by extended x-ray absorption fine structure spectroscopy at both absorption edges. Cu atoms adopt an elongated octahedral or square-based pyramidal oxygen environment which suggests mainly the presence of Cu(II) in the structure. Co adopts different local environments, depending on the electronic and spin states. © 2005 The American Physical Society.7114Er-Rakho, L., Michel, C., Lacorre, P., Raveau, B., (1988) J. 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Neutral weak currents in pion electroproduction on the nucleon

Parity violating asymmetry in inclusive scattering of longitudinally polarized electrons by unpolarized protons with $\pi^0$ or $\pi^+$ meson production, is calculated as a function of the momentum transfer squared $Q^2$ and the total energy $W$ of the $\pi N$-system. This asymmetry, which is induced by the interference of the one-photon exchange amplitude with the parity-odd part of the $Z^0$-exchange amplitude, is calculated for the $\gamma^*(Z^*)+p\to N+\pi$ processes ($\gamma^*$ is a virtual photon and $Z^*$ a virtual Z-boson) considering the $\Delta$-contribution in the $s-$channel, the standard Born contributions and vector meson ($\rho$ and $\omega$) exchanges in the $t-$channel. Taking into account the known isotopic properties of the hadron electromagnetic and neutral currents, we show that the P-odd term is the sum of two contributions. The main term is model independent and it can be calculated exactly in terms of fundamental constants. It is found to be linear in $Q^2$. The second term is a relatively small correction which is determined by the isoscalar component of the electromagnetic current. Near threshold and in the $\Delta$-region, this isoscalar part is much smaller (in absolute value) than the isovector one: its contribution to the asymmetry depend on the polarization state (longitudinal or transverse) of the virtual photon.Comment: 30 pages 9 figure

Beam instrumentation for the Tevatron Collider

The Tevatron in Collider Run II (2001-present) is operating with six times more bunches and many times higher beam intensities and luminosities than in Run I (1992-1995). Beam diagnostics were crucial for the machine start-up and the never-ending luminosity upgrade campaign. We present the overall picture of the Tevatron diagnostics development for Run II, outline machine needs for new instrumentation, present several notable examples that led to Tevatron performance improvements, and discuss the lessons for future colliders

Solidification of Al alloys under electromagnetic pulses and characterization of the 3D microstructures under synchrotron x-ray tomography

A novel programmable electromagnetic pulse device was developed and used to study the solidification of Al-15 pct Cu and Al-35 pct Cu alloys. The pulsed magnetic fluxes and Lorentz forces generated inside the solidifying melts were simulated using finite element methods, and their effects on the solidification microstructures were characterized using electron microscopy and synchrotron X-ray tomography. Using a discharging voltage of 120 V, a pulsed magnetic field with the peak Lorentz force of ~1.6 N was generated inside the solidifying Al-Cu melts which were showed sufficiently enough to disrupt the growth of the primary Al dendrites and the Al2Cu intermetallic phases. The microstructures exhibit a strong correlation to the characteristics of the applied pulse, forming a periodical pattern that resonates the frequency of the applied electromagnetic field

Differences in symptoms and cardiopulmonary responses to Treadmill versus Cycle cardiopulmonary exercise testing and comparison with the 6MWT in ILD

Aims: Cardiopulmonary exercise testing (CPET) is used for diagnostic and prognostic reasons in Interstitial Lung Disease (ILD). Our aims were to compare symptoms and cardiopulmonary responses between a) cycle and treadmill walking and b) between CPET and the 6MWT. Methods: 18 ILD patients (6 IPF; 12M), mean (SD) age 65.4 (12.6), FVC% pred. 72.7 (20.7), DLCO% pred. 42.2 (13.4) underwent CPET by cycle ergometry (C-CPET) and treadmill walking (T-CPET) in random order, with 30-45 min rest between tests, on a single session. On a second session 3-7 days apart, patients performed the 6MWT. Oxygen saturation (SpO2), heart rate (HR), breathlessness (BORG score) and leg fatigue/exertion (RPE scale) were recorded at rest, peak and at each minute of the 3-min recovery. We used the sign rank test with the null hypothesis of no difference between responses to the 3 tests of multiple CPET and symptom parameters. Results: Data were consistent with no differences between C-CPET and T-CPET in cardiopulmonary parameters (PeakVO2 p value=0.4, AT_VO2 p= 0.5, Peak VE/VCO2 p= 0.5, Peak VE/VO2 = 0.8). Desaturation (∆SpO2) was similar between T- CPET and C-CPET (p= 0.4) or 6MWT (0.7) but differed between C-CPET and 6MWT (p=0.03). The 3-minute SpO2 recovery was slower in T-CPET than the other tests. Change in HR (∆HR) and 3-min recovery was similar between CPET modes (p=0.1) but statistically lower in the 6MWT (p= 0.001). Breathlessness was greater in T-CPET than C-CPET (∆BORG p= 0.04) and recovery slower than the other two tests. Patients with CTD-ILD reported a preference for T-CPET. Summary/Conclusions: Cardiopulmonary parameters can be derived accurately from both types of CPET. The drop in oxygen saturation at the 6MWT was similar to that of the maximal T-CPET so, it can be used in ILD patients to estimate level of desaturation, even though the 6MWT underestimates the delay in SpO2 recovery. Funding source: This abstract presents independent research funded by the National Institute for Health Research (NIHR) under its Research for Patient Benefit (RfPB) Programme (Grant Reference Number PB-PG-1112-29067). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health, UK

Simultaneous Tune and Coupling Feedback in RHIC, and Possible Implications for LHC Commissioning

N/

On the Effect of Nb on the Microstructure and Properties of Next Generation Polycrystalline Powder Metallurgy Ni-Based Superalloys

Abstract The effect of Nb on the properties and microstructure of two novel powder metallurgy (P/M) Ni-based superalloys was evaluated, and the results critically compared with the Rolls-Royce alloy RR1000. The Nb-containing alloy was found to exhibit improved tensile and creep properties as well as superior oxidation resistance compared with both RR1000 and the Nb-free variant tested. The beneficial effect of Nb on the tensile and creep properties was due to the microstructures obtained following the post-solution heat treatments, which led to a higher γ′ volume fraction and a finer tertiary γ′ distribution. In addition, an increase in the anti-phase-boundary energy of the γ′ phase is also expected with the addition of Nb, further contributing to the strength of the material. However, these modifications in the γ′ distribution detrimentally affect the dwell fatigue crack-growth behavior of the material, although this behavior can be improved through modified heat treatments. The oxidation resistance of the Nb-containing alloy was also enhanced as Nb is believed to accelerate the formation of a defect-free Cr2O3 scale. Overall, both developmental alloys, with and without the addition of Nb, were found to exhibit superior properties than RR1000.This work was supported by the Rolls-Royce/EPSRC Strategic Partnership under EP/H022309/1, EP/H500375/1 and EP/ M005607/1

Inflating in a Better Racetrack

We present a new version of our racetrack inflation scenario which, unlike our original proposal, is based on an explicit compactification of type IIB string theory: the Calabi-Yau manifold P^4_[1,1,1,6,9]. The axion-dilaton and all complex structure moduli are stabilized by fluxes. The remaining 2 Kahler moduli are stabilized by a nonperturbative superpotential, which has been explicitly computed. For this model we identify situations for which a linear combination of the axionic parts of the two Kahler moduli acts as an inflaton. As in our previous scenario, inflation begins at a saddle point of the scalar potential and proceeds as an eternal topological inflation. For a certain range of inflationary parameters, we obtain the COBE-normalized spectrum of metric perturbations and an inflationary scale of M = 3 x 10^{14} GeV. We discuss possible changes of parameters of our model and argue that anthropic considerations favor those parameters that lead to a nearly flat spectrum of inflationary perturbations, which in our case is characterized by the spectral index n_s = 0.95.Comment: 20 pages, 7 figures. Brief discussion on the non-gaussianity of this model, one more figure of the field trajectories added as well as other minor changes to the tex