Inclusive-jet and dijet cross sections in deep inelastic scattering at HERA

Nuclear Physics B 765:1-2 (2007) 1-30

Authors:

S Chekanov, M Derrick, S Magill, S Miglioranzi, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, N Pavel, AG Yagües Molina, S Antonelli, P Antonioli, G Bari, M Basile, L Bellagamba, M Bindi, D Boscherini, A Bruni, G Bruni, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, G Iacobucci, A Margotti, R Nania, A Polini, L Rinaldi, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, E Paul, J Rautenberg, R Renner, U Samson, V Schönberg, M Wang, M Wlasenko, NH Brook, GP Heath, JD Morris, T Namsoo, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, KJ Ma, ZA Ibrahim, B Kamaluddin, WAT Wan Abdullah, Y Ning, Z Ren, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, M Gil, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bołd, I Grabowska-Bołd, D Kisielewska, J Łukasik, M Przybycień, L Suszycki, A Kotański, W Słomiński, V Adler, U Behrens, I Bloch, A Bonato, K Borras, N Coppola, J Fourletova, A Geiser, D Gladkov, P Göttlicher, I Gregor, O Gutsche, T Haas, W Hain, C Horn, B Kahle, U Kötz

Abstract:

Inclusive-jet and dijet differential cross sections have been measured in neutral current deep inelastic ep scattering for exchanged boson virtualities Q2 > 125   GeV2 with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. Jets were identified in the Breit frame using the kT cluster algorithm. Jet cross sections are presented as functions of several kinematic and jet variables. The results are also presented in different regions of Q2. Next-to-leading-order QCD calculations describe the measurements well. Regions of phase space where the theoretical uncertainties are small have been identified. Measurements in these regions have the potential to constrain the gluon density in the proton when used as inputs to global fits of the proton parton distribution functions. © 2006.

Bright quasi-phasematched soft x-ray harmonic radiation from Argon ions

(2007)

Authors:

M Zepf, B Dromey, M Landreman, P Foster, SM Hooker

Quasi-phasematching of harmonic generation via multimode beating in waveguides

(2007)

Authors:

B Dromey, M Zepf, M Landreman, SM Hooker

Transverse interferometry of a hydrogen-filled capillary discharge waveguide.

Phys Rev Lett 98:2 (2007) 025002

Authors:

AJ Gonsalves, TP Rowlands-Rees, BHP Broks, JJAM van der Mullen, SM Hooker

Abstract:

Transverse interferometric measurements are presented of the plasma channel formed in a hydrogen-filled capillary discharge waveguide recently used to generate 1 GeV electrons in a laser-driven plasma accelerator for the first time. The measurements were found to be in good agreement with nonlocal thermal equilibrium simulations, but showed significant differences with the results of a quasistatic model developed by Bobrova et al. [Phys. Rev. E. 65, 016407 (2001)]. The measurements are used to determine scaling laws for the axial electron density and matched spot size of the plasma channel, enabling optimization of the channel to specific applications.

Comparison of parallel and perpendicular polarized counterpropagating light for suppressing high harmonic generation

Journal of the Optical Society of America B: Optical Physics 24:9 (2007) 2421-2427

Authors:

M Landreman, K O'Keeffe, T Robinson, M Zepf, B Dromey, SM Hooker

Abstract:

The use of counterpropagating laser pulses to suppress high harmonic generation (HHG) is investigated experimentally for pulses polarized parallel or perpendicular to the driving laser pulse. It is shown for the first time that perpendicularly polarized pulses can suppress HHG. The intensity of the counterpropagating pulse required for harmonic suppression is found to be much larger for perpendicular polarization than for parallel polarization, in good agreement with simple models of the harmonic suppression. These results have applications to quasi-phase-matching of HHG with trains of counterpropagating pulses. © 2007 Optical Society of America.