A fast and precise method to solve the Altarelli-Parisi equations in x space

A numerical method to solve linear integro-differential equations is presented. This method has been used to solve the QCD Altarelli-Parisi evolution equations within the H1 Collaboration at DESY-Hamburg. Mathematical aspects and numerical approximations are described. The precision of the method is discussed.Comment: 18 pages, 4 figure

A new global analysis of deep inelastic scattering data

A new QCD analysis of Deep Inelastic Scattering (DIS) data is presented. All available neutrino and anti-neutrino cross sections are reanalysed and included in the fit, along with charged-lepton DIS and Drell-Yan data. A massive factorisation scheme is used to describe the charm component of the structure functions. Next-to-leading order parton distribution functions are provided. In particular, the strange sea density is determined with a higher accuracy with respect to other global fits.Comment: 51 pages, 18 figure

Laser beam-electron Compton scattering: technology and applications

The goal of this presentation is to introduce the properties and scientific interests of the laser beam-electron beam Compton scattering. There are many possible applications for this process but the main technical difficulty is the requested very high laser beam average power. The various solutions that are presently worked out to provide the requested average power will be reviewed as well as the various electron accelerator technologies. Finally, the various Compton machine operating at present and the future projects will be described

On the non-paraxial modes of two-dimensional nearly concentric resonators

to be published in Applied OpticsA non-paraxial scalar diffraction integral is used to determine numerically the resonance modes of a two dimensional nearly concentric Fabry-Perot resonator. Numerical examples are provided and results are compared to those published by Laabs and Friberg [IEEE J. Quant. El., vol. 35, pp. 198-207, 1999]. Discrepancies are reported and further discussed on the basis of the difference between the solution space supported by the numerical method used in the present work and the one used by Laabs and Friberg

Determination of s(x) and \bar{s}(x) from a global QCD analysis

A new global QCD analysis of DIS data is presented. The \nu Fe and \bar{\nu}Fe differential cross-section data are included to constrain the strange component of the nucleon sea. As a result we found a hard strangeness at high-x and some evidence for an asymmetry between xs(x) and x\bar{s}(x).Comment: 5 pages, 4 figure

Effect of Beam Dynamics Processes in the Low Energy Ring ThomX

As part of the R\&D for the 50 MeV ThomX Compton source project, we have studied the effect of several beam dynamics processes on the evolution of the beam in the ring. The processes studied include among others Compton scattering, intrabeam scattering, coherent synchrotron radiation. We have performed extensive simulations of a full injection/extraction cycle (400000 turns). We show how each of these processes degrades the flux of photons produced and how a feedback system contributes to recovering most of the flux.Comment: Submitted to IPAC'14, WEPRO00

Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring

Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of $e^-$ -- $e^+$ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-P\'erot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and is used to produce an intense flux of polarized gamma rays by Compton scattering \cite{ipac-mightylaser}. For electrons at the ATF energy (1.28 GeV) Compton scattering may result in a shorter lifetime due to the limited bucket acceptance. We have implemented the effect of Compton scattering on a 2D tracking code with a Monte-Carlo method. This code has been used to study the longitudinal dynamics of the electron beam at the ATF damping ring, in particular the evolution of the energy spread and the bunch length under Compton scattering. The results obtained are presented and discussed. Possible methods to observe the effect of Compton scattering on the ATF beam are proposed

Transmission matrix of a uniaxial optically active crystal platelet

Expressions corresponding to the transmission of a uniaxial optically active crystal platelet are provided for an optical axis parallel and perpendicular to the plane of interface. The optical activity is taken into account by a consistent multipolar expansion of the crystal medium response due to the path of an electromagnetic wave. Numerical examples of the effect of the optical activity are given for quartz platelets of chosen thicknesses. The optical activity's effects on the variations of the transmission of quartz platelets as a function of the angle of incidence is also investigated.Comment: 18 pages, 12 figures. Accepted to Optics Communications Journa