Gilardoni, S. S.

Paper	Title	Page
WEOAG02	Measurements of Heavy Ion Beam Losses from Collimation	1906
	R. Bruce, R. W. Assmann, G. Bellodi, C. Bracco, H.-H. Braun, S. S. Gilardoni, E. B. Holzer, J. M. Jowett, S. Redaelli, Th. Weiler, C. Zamantzas CERN, Geneva
	The collimation efficiency for Pb82+ ion beams in the LHC is predicted to be much lower than for protons. Nuclear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown sufficiently large. In this article we present measurements of loss patterns caused by a prototype LHC collimator in the CERN SPS. The loss maps show a qualitative difference between Pb82+ ions and protons, with the maximum loss rate observed at different places in the ring. This behaviour was predicted by simulations and provides a valuable benchmark of the simulations done for the LHC.
	Slides
WEPP006	Effects of Ultraperipheral Nuclear Collisions in the LHC and their Alleviation	2533
	R. Bruce, S. S. Gilardoni, J. M. Jowett CERN, Geneva
	Electromagnetic interactions between colliding heavy ions at the LHC are the sources of specific beam loss mechanisms that may quench superconducting magnets. We propose a simple yet efficient strategy to alleviate the effect of localized losses from bound-free pair production by spreading them out in several magnets by means of orbit bumps. We also consider the consequences of neutron emission by electromagnetic dissociation and show through simulations that ions modified by this process will be intercepted by the collimation system, without further modifications.
MOPC131	Ions for LHC: Towards Completion of the Injector Chain	376
	D. Manglunki, M. Albert, M.-E. Angoletta, G. Arduini, P. Baudrenghien, G. Bellodi, P. Belochitskii, E. Benedetto, T. Bohl, C. Carli, E. Carlier, M. Chanel, H. Damerau, S. S. Gilardoni, S. Hancock, D. Jacquet, J. M. Jowett, V. Kain, D. Kuchler, M. Martini, S. Maury, E. Métral, L. Normann, G. Papotti, S. Pasinelli, M. Schokker, R. Scrivens, G. Tranquille, J. L. Vallet, B. Vandorpe, U. Wehrle, J. Wenninger CERN, Geneva
	The CERN LHC experimental programme includes heavy ion physics with collisions between two counter-rotating Pb82+ ion beams at a momentum of 2.76 TeV/c/nucleon per beam and luminosities as high as 1·1027 cm-2 s-1. To achieve the beam parameters required for this operation the ion accelerator chain has undergone substantial modifications. Commissioning with beam of the various elements of this chain started in 2005 and in 2007 it was the turn of the final stage, the Super-Proton-Synchrotron (SPS) following extensive changes to the low-level RF hardware. The major limitations of this mode of operation of the SPS (space charge, intra-beam scattering) are presented, together with the performance reached so far. The status of the pre-injector performance will also be reviewed together with a description of the steps required to reach nominal performance.
THPC047	Studies of Losses During Continuous Transfer Extraction at the CERN proton Synchrotron	3083
	S. S. Gilardoni, J. Barranco CERN, Geneva
	Proton beams can be extracted from the CERN-PS at 14 GeV/c on five turns, using a technique called Continuous Transfer (CT). In this case, large losses due to particles scattered by an electrostatic septum used to slice the beam on five turns are observed in straight sections where the machine aperture is large enough to accommodate the circulating beam without any loss. These losses limit the maximum intensity deliverable to the SPS, like for the CERN to Gran Sasso (CNGS) neutrino program, because of the large irradiation of the site outside the PS tunnel and at the CERN fence. New simulation tools for a parametric study have been developed to improve the understanding of the observed loss pattern. A proposed solution to displace the losses in less critical section of the machine has been simulated and implemented in the CERN-PS. Simulations and experimental results of the loss study and reduction are presented.
THPC048	Study of Beam Losses at Transition Crossing at the CERN PS	3086
	S. S. Gilardoni, S. Aumon, M. Martini CERN, Geneva
	A series of studies has been carried out to understand and alleviate the beam losses in the CERN PS proton Synchrotron. In particular, losses appear at transition crossing during the pulsing of special quadrupoles used to create a gamma jump scheme and which causes a large optics and orbit distortion. After a brief summary of the gamma jump scheme at the PS, experimental and simulation results about the loss studies and reduction are presented.
THPC049	Progress in the Beam Preparation for the Multi-turn Extraction at the CERN Proton Synchrotron	3089
	S. S. Gilardoni, F. Franchi, M. Giovannozzi CERN, Geneva
	A new type of extraction based on beam trapping inside stable islands in the horizontal phase space will become operational during 2008 at the CERN Proton Synchrotron. A series of beam experiments was carried out to prove loss-less capture with high intensity and multi-bunched beams, up to 1500·1010 protons per pulse, in preparation of the extraction commissioning. These fundamental steps for the new Multi-turn Extraction are presented and discussed in details.
THPC050	Experimental Evidence of Beam Trapping with One-third and One-fifth Resonance Crossing	3092
	S. S. Gilardoni, F. Franchi, M. Giovannozzi CERN, Geneva
	Beam trapping in stable islands of the horizontal phase space generated by non-linear magnetic fields is realized by means of a given tune variation so to cross a resonance of order n. Whenever the resonance is stable, n+1 beamlets are created whereas if the resonance is unstable, the beam is split in n parts. Experiments at the CERN Proton Synchrotron showed protons trapped in stable islands while crossing the one-third and one-fifth resonance with the creation of 3 and 6 stable beamlets, respectively. The results are presented and discussed in details.
THPC051	Adiabaticity and Reversibility Studies for Beam Splitting Using Stable Resonances	3095
	S. S. Gilardoni, F. Franchi, M. Giovannozzi CERN, Geneva
	At the CERN Proton Synchrotron, a series of beam experiments proved beam splitting by crossing the one-fourth resonance. Depending on the speed at which the horizontal resonance is crossed, the splitting process is more or less adiabatic, and a different fraction of the initial beam is trapped in the islands. Experiments prove that when the trapping process is reversed and the islands merged together, the final distribution features thick tails. The beam population in such tails is correlated to the speed of the resonance crossing and to the fraction of the beam trapped in the stable islands. Experiments, simulations, and possible theoretical explanations are discussed.