Métral, E.

Paper	Title	Page
MOPLT006	The New Layout of the LHC Cleaning Insertions	539
	R.W. Assmann, O. Aberle, O.S. Brüning, S. Chemli, D. Gasser, J.-B. Jeanneret, J.M. Jimenez, V. Kain, E. Métral, G. Peon, S. Ramberger, C. Rathjen, T. Risselada, F. Ruggiero, L. Vos CERN, Geneva D. Kaltchev TRIUMF, Vancouver
	The improved LHC collimation system required significant changes in the layout and design of the warm insertion IR7. Requirements for collimation, optics, impedance, vacuum, and additional infrastructure are described and the adopted layout is discussed. Various design principles have been explored during the re-design, ranging from a regular 90 degree lattice and special low impedance lattices to an option with additional warm quadrupole units that could have extended the usable space for collimator installations in the insertion. The various constraints for the optics and cleaning design in the LHC cleaning insertions are summarized. Magnet positions and collimators were moved significantly, such that a good cleaning efficiency was maintained while impedance was reduced by a factor of two. Metallic phase 2 collimators allow a better efficiency than originally achievable and additional scrapers were allocated. The required infrastructure was specified, including a powerful cooling system for the collimators.
MOPLT005	An Improved Collimation System for the LHC	536
	R.W. Assmann, O. Aberle, A. Bertarelli, H.-H. Braun, M. Brugger, L. Bruno, O.S. Brüning, S. Calatroni, E. Chiaveri, B. Dehning, A. Ferrari, B. Goddard, E.B. Holzer, J.-B. Jeanneret, J.M. Jimenez, V. Kain, M. Lamont, M. Mayer, E. Métral, R. Perret, S. Redaelli, T. Risselada, G. Robert-Demolaize, S. Roesler, F. Ruggiero, R. Schmidt, D. Schulte, P. Sievers, V. Vlachoudis, L. Vos, G. Vossenberg, J. Wenninger CERN, Geneva I.L. Ajguirei, I. Baishev, I.L. Kurochkin IHEP Protvino, Protvino, Moscow Region D. Kaltchev TRIUMF, Vancouver H. Tsutsui SHI, Tokyo
	The LHC design parameters extend the maximum stored beam energy 2-3 orders of magnitude beyond present experience. The handling of the high-intensity LHC beams in a super-conducting environment requires a high-robustness collimation system with unprecedented cleaning efficiency. For gap closures down to 2mm no beam instabilities may be induced from the collimator impedance. A difficult trade-off between collimator robustness, cleaning efficiency and collimator impedance is encountered. The conflicting LHC requirements are resolved with a phased approach, relying on low Z collimators for maximum robustness and hybrid metallic collimators for maximum performance. Efficiency is further enhanced with an additional cleaning close to the insertion triplets. The machine layouts have been adapted to the new requirements. The LHC collimation hardware is presently under design and has entered into the prototyping and early testing phase. Plans for collimator tests with beam are presented.
WEOALH02	Multiturn Extraction Based on Trapping in Stable Islands at CERN PS: Recent Measurement Advances	173
	M. Giovannozzi, R. Cappi, S.G. Gilardoni, M. Martini, E. Métral, A. Sakumi, R.R. Steerenberg CERN, Geneva A.-S. Müller FZK-ISS-ANKA, Karlsruhe
	Recently a novel approach to perform multi-turn extraction was proposed based on beam splitting in the transverse phase space by means of trapping inside stable islands. During the year 2002 run, preliminary measurements at the CERN Proton Synchrotron with a low-intensity, single-bunch, proton beam, confirmed the possibility of generating various beamlets starting from a single Gaussian beam. The experimental campaign continued also in the year 2003 run to assess a number of key issues, such as feasibility of trapping with high-intensity beam, capture efficiency, and multi-turn extraction proper. The experimental results are presented and discussed in detail in this paper.
	Video of talk
	Transparencies
WEPLT023	Transverse Resistive Wall Impedance and Wake Function with Inductive Bypass	1873
	A. Koschik, F. Caspers, E. Métral, L. Vos CERN, Geneva B. Zotter Honorary CERN Staff Member, Grand-Saconnex
	We analyze the resistive wall impedance with an "inductive bypass" due to alternate current paths in the outer vacuum chamber proper. Also the corresponding wake function has been obtained which is useful for the simulation of beam stability in the time domain. Results are presented for the LHC.
WEPLT029	Intensity Dependent Emittance Transfer Studies at the CERN Proton Synchrotron	1891
	E. Métral, C. Carli, M. Giovannozzi, M. Martini, R.R. Steerenberg CERN, Geneva G. Franchetti, I. Hofmann GSI, Darmstadt J. Qiang LBNL, Berkeley, California R.D. Ryne LBNL/CBP, Berkeley, California
	An intensive study has been undertaken since the year 2002 to understand better the various high-intensity bottlenecks of the CERN Proton Synchrotron machine. One of these limitations comes from the so-called Montague resonance. High-intensity proton synchrotrons, having larger horizontal than vertical emittance, may suffer from this fourth-order coupling resonance driven by space charge only. In particular, such resonance may lead to emittance sharing and, possibly, beam loss due to vertical acceptance limitation. Experimental observations made in the 2002 and 2003 runs on the Montague resonance are presented in this paper and compared with 3D particle-in-cell simulation results and theoretical predictions.
WEPLT030	Stability Diagrams for Landau Damping with Two-dimensional Betatron Tune Spread from Both Octupoles and Non-linear Space Charge applied to the LHC at Injection	1894
	E. Métral, F. Ruggiero CERN, Geneva
	The joint effect of space-charge non-linearities and octupole lenses is discussed for the case of a quasi-parabolic transverse distribution of a monochromatic beam. The self-consistent non-linear space-charge tune shift corresponding to the above distribution function is first derived analytically. The exact dispersion relation is also given but not solved. Instead, noting that a good approximation of the non-linear space-charge tune shift is obtained considering only linear terms in the action variables, the dispersion relation is solved analytically in this approximate case. As expected, in the absence of external (octupolar) non-linearities, the result of Möhl and Schönauer is recovered: there is no stability region. In the absence of space charge, the stability diagrams of Berg and Ruggiero are also recovered. Finally, the new result is applied to the LHC at injection.
WEPLT168	ORBIT Benchmark of Space-charge-induced Emittance Growth in the CERN PS	2218
	S.M. Cousineau, J.A. Holmes ORNL/SNS, Oak Ridge, Tennessee E. Métral CERN, Geneva
	Particle tracking codes provide an invaluable tool in the design and operation of high intensity machines. An important task in the development of these codes is the validation of the space charge models through benchmark with experimental data. Presented here are benchmarks of the ORBIT particle tracking code with recent measurements of space-charge-induced transverse emittance growth in the CERN PS machine. Benchmarks of two experimental data sets are performed: Integer resonance crossing, and Montague resonance crossing.