Near-Threshold Neutral Pion Electroproduction at High Momentum Transfers and Generalized Form Factors

We report the measurement of near-threshold neutral pion electroproduction cross sections and the extraction of the associated structure functions on the proton in the kinematic range Q2 from 2 to 4.5 GeV2 and W from 1.08 to 1.16 GeV. These measurements allow us to access the dominant pion-nucleon s-wave multipoles E0+ and S0+ in the near-threshold region. In the light-cone sum-rule framework (LCSR), these multipoles are related to the generalized form factors Gπ0p1(Q2) and Gπ0p2(Q2). The data are compared to these generalized form factors and the results for Gπ0p1(Q2) are found to be in good agreement with the LCSR predictions, but the level of agreement with Gπ0p2(Q2) is poor

Separated structure functions for the exclusive electroproduction of K+Λ and K+Σ0 final states

We report measurements of the exclusive electroproduction of K+Λ and K+Σ0 final states from a proton target using the Continuous Electron Beam Accelerator Facility (CEBAF) large-acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions σT,σL,σTT, and σLT were extracted from the Φ- and ε-dependent differential cross sections taken with electron beam energies of 2.567, 4.056, and 4.247 GeV. This analysis represents the first σL/σT separation with the CLAS detector, and the first measurement of the kaon electroproduction structure functions away from parallel kinematics. The data span a broad range of momentum transfers from 0.

Onset of asymptotic scaling in deuteron photodisintegration

We investigate the transition from the nucleon-meson to the quark-gluon description of the strong interaction using the photon energy dependence of the d(γ,p)n differential cross section for photon energies above 0.5 GeV and center-of-mass proton angles between 30° and 150°. A possible signature for this transition is the onset of cross-section s-11 scaling with the total energy squared, s, at some proton transverse momentum PT. The results show that the scaling has been reached for proton transverse momentum above about 1.1  GeV/c. This may indicate that the quark-gluon regime is reached above this momentum

Electroproduction of the Λ(1520) hyperon

The reaction ep⃗ e′K+Λ(1520) with Λ(1520)→p′K- was studied at electron beam energies of 4.05, 4.25, and 4.46 GeV, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cosθK+, φK+, Q2, and W dependencies of Λ(1520) electroproduction are presented for the kinematic region 0.

Electroproduction of phi(1020) mesons at 1.4 \u3c= Q(2) \u3c= 3.8 GeV2 measured with the CLAS spectrometer

Electroproduction of exclusive ϕ vector mesons has been studied with the CLAS detector in the kinematic range 1.

Ratios of 15N/12C and 4He/12C inclusive electroproduction cross sections in the nucleon resonance region

The (W,Q2) dependence of the ratio of inclusive electron scattering cross sections for 15N/12C was determined in the kinematic ranges 0.

The inverse stationary heat conduction problem for a cuboid

The heat conductivity coefficient is important characteristic which is used in various spheres. The original methodic for conductivity coefficient determination was proposed for samples in form of rectangular parallelepiped. The results of numerical solution of nonlinear heat conduction problem in heat conduction coefficient value range 0.04-5 W/(m K) with different sample relative size were presented

G0^0 Electronics and Data Acquisition (Forward-Angle Measurements)

The G$^0$ parity-violation experiment at Jefferson Lab (Newport News, VA) is designed to determine the contribution of strange/anti-strange quark pairs to the intrinsic properties of the proton. In the forward-angle part of the experiment, the asymmetry in the cross section was measured for $\vec{e}p$ elastic scattering by counting the recoil protons corresponding to the two beam-helicity states. Due to the high accuracy required on the asymmetry, the G$^0$ experiment was based on a custom experimental setup with its own associated electronics and data acquisition (DAQ) system. Highly specialized time-encoding electronics provided time-of-flight spectra for each detector for each helicity state. More conventional electronics was used for monitoring (mainly FastBus). The time-encoding electronics and the DAQ system have been designed to handle events at a mean rate of 2 MHz per detector with low deadtime and to minimize helicity-correlated systematic errors. In this paper, we outline the general architecture and the main features of the electronics and the DAQ system dedicated to G$^0$ forward-angle measurements.Comment: 35 pages. 17 figures. This article is to be submitted to NIM section A. It has been written with Latex using \documentclass{elsart}. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment In Press (2007

Anti-HBs re-seroconversion after liver transplantation in a patient with past HBV infection receiving a HBsAg positive graft

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