Professor Brian Foster OBE, FRS

Abstract:

FLASHForward (FFV∗-) is the Future-ORiented Wakefield Accelerator Research and Development project at the DESY free-electron laser (FEL) facility FLASH. It aims to produce high-quality, GeV-energy electron beams over a plasma cell of a few centimeters. The plasma is created by means of a 25 TW Ti: Sapphire laser system. The plasma wakefield will be driven by high-current-density electron beams extracted from the FLASH accelerator. The project focuses on the advancement of plasma-based particle acceleration technology through the exploration of both external and internal witness-beam injection schemes. Multiple conventional and cutting-edge diagnostic tools, suitable for diagnosis of short electron beams, are under development. The design of the post-plasma beamline sections will be finalized based on the result of these aforementioned diagnostics. In this paper, the status of the project, as well as the progress towards achieving its overarching goal of demonstrating FEL gain via plasma wakefield acceleration, is discussed.

Abstract:

A simultaneous electroweak and QCD fit of electroweak parameters and parton distribution functions to HERA data on deep inelastic scattering is presented. The input data are neutral current and charged current inclusive cross sections measured by the H1 and ZEUS collaborations at the $ep$ collider HERA. The polarization of the electron beam was taken into account for the ZEUS and H1 data recorded between 2004 and 2007. Results are presented on the vector and axial-vector couplings of the $Z$ boson to $u-$ and $d-$type quarks. The values are in agreement with Standard Model predictions. The results on $au$ and $vu$ represent the most precise measurements from a single process.

Abstract:

A search for a narrow baryonic state in the pKS0 and pKS0 system has been performed in ep collisions at HERA with the ZEUS detector using an integrated luminosity of 358pb-1 taken in 2003-2007. The search was performed with deep inelastic scattering events at an ep centre-of-mass energy of 318GeV for exchanged photon virtuality, Q2, between 20 and 100GeV2. Contrary to evidence presented for such a state around 1.52 GeV in a previous ZEUS analysis using a sample of 121 pb-1 taken in 1996-2000, no resonance peak was found in the p(p)KS0 invariant-mass distribution in the range 1.45-1.7 GeV. Upper limits on the production cross section are set.