All-optical steering of laser-wakefield-accelerated electron beams
Physical Review Letters 105:21 (2010)
Abstract:
We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations. © 2010 The American Physical Society.Micron size laser-wire system at the ATF extraction line, recent results and ATF-II upgrade
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 623:1 (2010) 564-566
Abstract:
The KEK Accelerator test facility (ATF) extraction line laser-wire system has been upgraded last year allowing the measurement of micron scale transverse size electron beams. The last measurements using the upgraded system from recent operation at the ATF are presented, demonstrating raw measurements of order 3μm RMS. The main component contributions to this measurement are also discussed. © 2010 Elsevier B.V. All rights reserved.First milestone on the path toward a table-top free-electron laser (FEL)
AIP Conference Proceedings 1228 (2010) 295-300
Abstract:
Latest developments in the field of laser-wakefield accelerators (LWFAs) have led to relatively stable electron beams in terms of peak energy, charge, pointing and divergence from mmsized accelerators. Simulations and LWFA theory indicate that these beams have low transverse emittances and ultrashort bunch durations on the order of ∼ 10 fs. These features make LWFAs perfectly suitable for driving high-brightness X-ray undulator sources and free-electron lasers (FELs) on a university-laboratory scale.With the detection of soft-X-ray radiation from an undulator source driven by laser-wakefield accelerated electrons, we succeeded in achieving a first milestone on this path. The source delivers remarkably stable photon beams which is mainly due to the stable electron beam and our miniature magnetic quadrupole lenses, which significantly reduce its divergence and angular shot-to-shot variation. An increase in electron energy allows for compact, tunable, hard-Xray undulator sources. Improvements of the electron beams in terms of charge and energy spread will put table-top FELs within reach. © 2010 American Institute of Physids.Measurement of beauty production in DIS and F2 bb̄ extraction at ZEUS: The ZEUS Collaboration
European Physical Journal C 69:3 (2010) 347-360
Abstract:
Beauty production in deep inelastic scattering with events in which a muon and a jet are observed in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb-1. The fraction of events with beauty quarks in the data was determined using the distribution of the transverse momentum of the muon relative to the jet. The cross section for beauty production was measured in the kinematic range of photon virtuality, Q2>2 GeV2, and inelasticity, 0.05Combined measurement and QCD analysis of the inclusive e ±p scattering cross sections at HERA
Journal of High Energy Physics 2010:1 (2010)