Three- and four-jet final states in photoproduction at HERA
Nuclear Physics B 792:1-2 (2008) 1-47
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.ATF extraction line laser-wire system
Particle Accelerator Conference 2007: Particle Accelerator Conference, 2007. PAC. IEEE (2008)
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.Development of a high power fibre laser for laser based electron beam diagnostics
EPAC 2008 - Contributions to the Proceedings (2008) 1359-1361
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.Hadronic final states and QCD: Summary
DIS 2008 - Proceedings of the 16th International Workshop on Deep-Inelastic Scattering and Related Topics (2008)
Abstract:
A summary of new experimental results and recent theoretical developments discussed in the "Hadronic Final States and QCD" working group is presented.Measurement of isolated photon production in deep-inelastic scattering at HERA
European Physical Journal C 54:3 (2008) 371-387