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Diffractive photoproduction of dijets in ep collisions at HERA

European Physical Journal C 55:2 (2008) 177-191

Authors:

S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, M Jechow, N Pavel, AGY 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, G Sartorelli, A Zichichi, D Bartsch, I Brock, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, AE Nuncio-Quiroz, E Paul, R Renner, U Samson, V Schönberg, R Shehzadi, M Wlasenko, NH Brook, GP Heath, JD Morris, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, 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, C Blohm, A Bonato, K Borras, R Ciesielski, N Coppola, V Drugakov, S Fang, J Fourletova, A Geiser, D Gladkov, P Göttlicher, J Grebenyuk, I Gregor, T Haas, W Hain, A Hüttmann, B Kahle, II Katkov, U Klein, U Kötz

Abstract:

Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb-1. The measurements were made in the kinematic range Q2 < 1 GeV 2, 0.207.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5<ηjet<1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton. © 2008 Springer-Verlag / Società Italiana di Fisica.
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Three- and four-jet final states in photoproduction at HERA

Nuclear Physics B 792:1-2 (2008) 1-47

Authors:

S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, M Jechow, 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, G Sartorelli, A Zichichi, D Bartsch, I Brock, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, AE Nuncio-Quiroz, E Paul, R Renner, U Samson, V Schönberg, R Shehzadi, M Wlasenko, NH Brook, GP Heath, JD Morris, 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, C Blohm, A Bonato, K Borras, R Ciesielski, N Coppola, A Dossanov, V Drugakov, J Fourletova, A Geiser, D Gladkov, P Göttlicher, J Grebenyuk, I Gregor, T Haas, W Hain, C Horn, A Hüttmann, B Kahle

Abstract:

Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121   pb -1. The results are presented for jets with transverse energy E Tjet > 6   GeV and pseudorapidity | η jet | < 2.4, in the kinematic region given by the virtuality of the photon Q 2 < 1   GeV 2 and the inelasticity 0.2 ≤ y ≤ 0.85 and in two mass regions defined as 25 ≤ M n j < 50   GeV and M n j ≥ 50   GeV, where M n j is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O (α α s2) perturbative QCD calculation. © 2007 Elsevier B.V. All rights reserved.
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Laser-driven acceleration of electrons in a partially ionized plasma channel.

Phys Rev Lett 100:10 (2008) 105005

Authors:

TP Rowlands-Rees, C Kamperidis, S Kneip, AJ Gonsalves, SPD Mangles, JG Gallacher, E Brunetti, T Ibbotson, CD Murphy, PS Foster, MJV Streeter, F Budde, PA Norreys, DA Jaroszynski, K Krushelnick, Z Najmudin, SM Hooker

Abstract:

The generation of quasimonoenergetic electron beams, with energies up to 200 MeV, by a laser-plasma accelerator driven in a hydrogen-filled capillary discharge waveguide is investigated. Injection and acceleration of electrons is found to depend sensitively on the delay between the onset of the discharge current and the arrival of the laser pulse. A comparison of spectroscopic and interferometric measurements suggests that injection is assisted by laser ionization of atoms or ions within the channel.
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ATF extraction line laser-wire system

Particle Accelerator Conference 2007: Particle Accelerator Conference, 2007. PAC. IEEE (2008)

Authors:

L Deacon, ST Boogert, GA Blair, G Boorman, A Bosco, P Karataev, Laura Corner, N Delerue, B Foster, F Gannaway, D Howell, M Newman, Armin Reichold, R Senanayake, R Walczak, A Aryshev, H Hayano, K Kubo, N Terunuma, U Urakawa

Abstract:

The ATF extraction line laser-wire (LW) aims to achieve a micron-scale laser spot size and to verify that micron scale beam profile measurements can be performed at the International Linear Collider beam delivery system. Recent upgrades to the LW system are presented together with recent results including the first use of the LW as a beam diagnostic tool.
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Development of a high power fibre laser for laser based electron beam diagnostics

EPAC 2008 - Contributions to the Proceedings (2008) 1359-1361

Authors:

L Corner, LJ Nevay, N Delerue, DF Howell, M Newman, R Walczak, GA Blair, ST Boogert

Abstract:

We present the latest results on the development of a high power fibre laser system for use in a linear collider laser-wire experiment. The laser consists of a solid state oscillator which can be synchronised to an external frequency reference, and two amplification stages in double clad doped fibre, giving 1μJ pulses in a burst mode suitable for a linear collider laser-wire system. This output is amplified in large mode area photonic crystal fibre to generate the high pulse energy necessary for Compton scattering without any deleterious nonlinear effects, whilst maintaining the high spatial mode quality and beam pointing stability of a fibre laser. These properties are essential for producing the sub-micron spot sizes required for the measurement of small particle beam sizes.