• M. Petrarca, H.-H. Braun, N. Champault, E. Chevallay, R. Corsini, A.E. Dabrowski, M. Divall Csatari, S. Döbert, K. Elsener, V. Fedosseev, G. Geschonke, R. Losito, A. Masi, O. Mete, L. Rinolfi
  CERN, Geneva
• G. Bienvenu, M. Joré, B.M. Mercier, C. Prevost, R. Roux
  LAL, Orsay
• C. Vicario
  INFN/LNF, Frascati (Roma)

Installation of the new photo-injector for the CTF3 drive beam (PHIN) has been completed on a stand-alone test bench. The photo-injector operates with a 2.5 cell RF gun at 3 GHz, using a Cs2Te photocathode illuminated by a UV laser beam. The test bench is equipped with different beam monitoring devices as well as a 90-degree spectrometer. A grid of 200 micrometer wide slits can be inserted for emittance measurements. The laser used to trigger the photo-emission process is a Nd:YLF system consisting of an oscillator and a preamplifier operating at 1.5 GHz and two powerful amplifier stages. The infrared radiation produced is frequency quadrupled in two stages to obtain the UV. A Pockels cell allows adjusting the length of the pulse train between 50 nanoseconds and 50 microseconds. The nominal train length for CTF3 is 1.272 microseconds (1908 bunches). The first electron beam in PHIN was produced in November 2008. In this paper, results concerning the operation of the laser system and measurements performed to characterize the electron beam are presented.

• M.D. Salt
  UMAN, Manchester
• R. Appleby, K. Elsener
  CERN, Geneva
• A. Ferrari
  Uppsala University, Uppsala

The CLIC beam delivery system focuses 1.5 TeV electron and positron beams to a nanometre-sized cross section when colliding them at the interaction point (IP). The intense focusing leads to large beam-beam effects, causing the production of beamstrahlung photons, coherent and incoherent electron-positron pairs, as well as a significant disruption of the main beam. The transport of the post-collision beams requires a minimal loss extraction line, with high acceptance for energy deviation and divergence. The current design includes vertical bends close to the IP in order to separate the charged particles with a sign opposite to the main beam into a diagnostic-equipped intermediate dump, whilst transporting the photons and the main beam to the main dump. Photon and charged particle losses on the collimators and dumps result in a complex radiation field and IP background particle fluxes. In this paper, the electromagnetic backgrounds at the IP, which arise from these losses, are calculated, and the potential impact on the detector is discussed.