Laser-plasma accelerator group

Abstract:

The staged electron laser acceleration (STELLA) experiment demonstrated staging between two laser-driven devices, high trapping efficiency of microbunches within the accelerating field and narrow energy spread during laser acceleration. These are important for practical laser-driven accelerators. STELLA used inverse free electron lasers, which were chosen primarily for convenience. Nevertheless, the STELLA approach can be applied to other laser acceleration methods, in particular, laser-driven plasma accelerators. STELLA is now conducting experiments on laser wakefield acceleration (LWFA). Two novel LWFA approaches are being investigated. In the first one, called pseudo-resonant LWFA, a laser pulse enters a low-density plasma where nonlinear laser/plasma interactions cause the laser pulse shape to steepen, thereby creating strong wakefields. A witness e-beam pulse probes the wakefields. The second one, called seeded self-modulated LWFA, involves sending a seed e-beam pulse into the plasma to initiate wakefield formation. These wakefields are amplified by a laser pulse following shortly after the seed pulse. A second e-beam pulse (witness) follows the seed pulse to probe the wakefields. These LWFA experiments will also be the first ones driven by a CO2 laser beam. © 2006 The Royal Society.

Abstract:

Differential inclusive jet cross sections in neutral current deep inelastic ep scattering have been measured with the ZEUS detector using an integrated luminosity of 38.7 pb-1. The jets have been identified using the kT cluster algorithm in the longitudinally invariant inclusive mode in the laboratory frame; they have been selected with jet transverse energy, ETjet above 6 GeV and jet pseudorapidity, ηjet, between -1 and 3. Measurements of cross sections as functions of ETjet, Björken x and the photon virtuality, Q2, are presented. Three phase-space regions have been selected in order to study parton dynamics from the most global to the most restrictive region of forward-going (close to the proton-beam direction) jets at low x, where the effects of BFKL evolution might be present. The measurements have been compared to the predictions of leading-logarithm parton-shower Monte Carlo models and fixed-order perturbative QCD calculations. In the forward region, O (αs1) QCD calculations underestimate the data up to an order of magnitude at low x. An improved description of the data in this region is obtained by including O (αs2) QCD corrections, which account for the lowest-order t̂-channel gluon-exchange diagrams, highlighting the importance of such terms in the parton dynamics at low x. © 2005 Elsevier B.V. All rights reserved.

Abstract:

33 mm plasma channels produced in a gas-filled capillary discharge and 40 TW, 40 fs laser pulses were used to produce GeV electron beams in a multi-table-top setup. © 2006 Optical Society of America.

Abstract:

33 mm plasma channels produced in a gas-filled capillary discharge and 40 TW, 40 fs laser pulses were used to produce GeV electron beams in a multi-table-top setup. ©2006 Optical Society of America.