• I. Efthymiopoulos, A. Fabich, A. Grudiev, F. Haug, J. Lettry, M. Palm, H. Pereira, H. Pernegger, R.R. Steerenberg
  CERN, Geneva
• J.R.J. Bennett
  STFC/RAL/ASTeC, Chilton, Didcot, Oxon
• O. Caretta, P. Loveridge
  STFC/RAL, Chilton, Didcot, Oxon
• A.J. Carroll, V.B. Graves, P.T. Spampinato
  ORNL, Oak Ridge, Tennessee
• H.G. Kirk, H. Park, T. Tsang
  BNL, Upton, Long Island, New York
• K.T. McDonald
  PU, Princeton, New Jersey
• N.V. Mokhov, S.I. Striganov
  Fermilab, Batavia

The MERIT experiment is a proof-of-principle test of a target system for high power proton beam to be used as front-end for a neutrino factory complex or a muon collider. The experiment took data in autumn 2007 with the fast extracted beam from the CERN Proton Synchrotron (PS) to a maximum intensity of about 30·10¹² protons per pulse. We report results from the portion of the MERIT experiment in which separated beam pulses were delivered to a free mercury jet target with time intervals between pulses varying from 2 to 700 microseconds. The analysis is based on the responses of particle detectors placed along side and downstream of the target.

• S.S. Gilardoni, F. Arnold Malandain, E. Benedetto, T. Bohl, S. Cettour Cave, K. Cornelis, H. Damerau, F. Follin, T. Fowler, F. Franchi, P. Freyermuth, H. Genoud, R. Giachino, M. Giovannozzi, S. Hancock, Y. Le Borgne, D. Manglunki, G. Metral, L. Pereira, J.P. Ridewood, Y. Riva, M. Schokker, L. Sermeus, R.R. Steerenberg, B. Vandorpe, J. Wenninger
  CERN, Geneva

The Multi-Turn Extraction, a new type of extraction based on beam trapping inside stable islands in the horizontal phase space, has been commissioned during the 2008 run of the CERN Proton Synchrotron. Both single- and multi-bunch beams with a total intensity up to 1.4×10¹³ protons have been extracted with efficiencies up to 98%. Furthermore, injection tests in the CERN Super Proton Synchrotron were performed, with the beam then accelerated and extracted to produce neutrinos for the CERN Neutrino to Gran Sasso experiments. The results of the extensive measurement campaign are presented and discussed in details.

• S.S. Gilardoni, D. Allard, M.J. Barnes, O.E. Berrig, A. Beuret, D. Bodart, P. Bourquin, R. Brown, M. Caccioppoli, F. Caspers, J.-M. Cravero, C.G.A. Dehavay, T. Dobers, M. Dupont, G. Favre, T. Fowler, F. Franchi, M. Giovannozzi, J. Hansen, M. Karppinen, C. Lacroix, E. Mahner, V. Mertens, J. Monteiro, R. Noulibos, E. Page, R. Principe, C. Rossi, L. Sermeus, R.R. Steerenberg, G. Vandoni, G. Villiger, Th. Zickler, C. de Almeida Martins
  CERN, Geneva

The implementation of new Multi-turn extraction at the CERN Proton Synchrotron required major hardware changes for the nearly 50-year old accelerator. The installation of new PFNs and refurbished kicker magnets for the extraction, new sextupole and octupole magnets, new power converters, together with an in-depth review of the machine aperture leading to the design of new vacuum chambers was required. As a result, a heavy programme of interventions had to be scheduled during the winter shut-down 2007-8. The newly installed hardware and its commissioning is presented and discussed in details.

• S. Aumon, W. Bartmann, S.S. Gilardoni, E. Métral, G. Rumolo, R.R. Steerenberg
  CERN, Geneva
• B. Salvant
  EPFL, Lausanne

The CERN PS crosses transition energy at about 6 GeV by using a second order gamma jump performed with special quadrupoles. However, for high-intensity beams, and in particular the single bunch beam for the neutron Time-of-Flight facility, a controlled longitudinal emittance blow-up is still needed to prevent a fast single-bunch vertical instability from developing near transition. A series of studies have been done in the PS in 2008 to measure the beam behaviour near transition energy for different settings of the gamma transition jump. The purpose of this paper is to compare those measurements with simulations results from the HEADTAIL code, which should allow to understand better the different mechanisms involved and maybe improve the transition crossing.