Exclusive Rho Rho Production in Tagged Gamma-Gamma Interactions at LEP

Exclusive rho rho production in two-photon collisions between a quasi-real, gamma, and a virtual, gamma*, photons is studied at LEP at centre-of-mass energies 89 GeV < sqrt{s} < 209 GeV with a total integrated luminosity of 854.7 pb-1. The cross sections of the gamma gamma* -> rho rho processes are determined as a function of the photon virtuality, Q^2, and the two-photon centre-of-mass energy, Wgg, in the kinematic region: 0.2 GeV^2 < Q^2 < 30 GeV^2 and 1.1 GeV < Wgg < 3 GeV.Comment: 4 pages, 2 figures. Talk on XXXXth Rencontres de Moriond, "QCD and High Energy Hadronic Interactions", La Thuile, Italy, March 12 to 19, 200

Development of hollow electron beams for proton and ion collimation

Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.Comment: 3 pp. 1st International Particle Accelerator Conference: IPAC'10, 23-28 May 2010: Kyoto, Japa