01 Circular Colliders

A01 Hadron Colliders

Paper	Title	Page
MOXAGM01	Status of the Large Hadron Collider (LHC)	1
	F. Bordry CERN, Geneva
	The status of the LHC commissioning is presented. Preparation for smooth beam commissioning is going on since several years: very thorough commissioning of the highly complex hardware systems started already in 2005 preparation of the LHC beam commissioning, resulting in detailed procedures for various commissioning phases with increasing beam intensity and performance preparation of the injector complex, with beam up to the end of the transfer lines between SPS and LHC.
	Slides
WEPP001	Energy Loss of Coasting Gold Ions and Deutrons in RHIC	2518
	N. P. Abreu, M. Blaskiewicz, K. A. Brown, J. J. Butler, W. Fischer, M. Harvey, S. Tepikian BNL, Upton, Long Island, New York H. Burkhardt CERN, Geneva
	The total energy loss of coasting gold ion beams was measured at RHIC at two energies, corresponding to a gamma of 75.2 and 107.4. We describe the experiment and observations and compare the measured total energy loss with expectations from ionization losses at the residual gas, the energy loss due to impedance and synchrotron radiation. We find that the measured energy losses are below what is expected from free space synchrotron radiation. We believe that this shows evidence for suppression of synchrotron radiation which is cut off at long wavelength by the presence of the conducting beam pipe.
WEPP002	The Effect of Head-on Beam-beam Compensation on the Stochastic Boundaries and Particle Diffusion in RHIC	2521
	N. P. Abreu, W. Fischer, Y. Luo, G. Robert-Demolaize BNL, Upton, Long Island, New York
	To compensate the effects from the head-on beam-beam interactions in the polarized proton operation in the Relativistic Heavy Ion Collider (RHIC), an electron lens (e-lens) is proposed to collide head-on with the proton beam. We used an extended version of SixTrack for multiparticle beam-beam simulation in order to study the effect of the e-lens on the stochastic boundary and also on diffusion. The stochastic boundary was analyzed using Lypunov exponents and the diffusion was characterized as the average rms spread of the action after 104 turns. For both studies the simulations were performed with and without the e-lens and with full and partial compensation.
WEPP003	Optics Flexibility in the LHC at Top Energy	2524
	M. Aiba, H. Burkhardt, S. D. Fartoukh, M. Giovannozzi, S. M. White CERN, Geneva
	We report on studies of optics flexibility which allow for tune changes of the order of half a unit at top energy in the LHC. We describe how this could be done using one or several of the insertions IR2, IR4, IR8 or the main quadrupoles and discuss and compare the implications. This flexibility could be used to compensate for the loss in tune for high beta optics and may make it feasible to use the standard injection and ramp for these configurations. Potential further applications are also highlighted.
WEPP004	Overall Optics Solutions for Very High Beta in Atlas	2527
	S. M. White, H. Burkhardt, P. M. Puzo CERN, Geneva S. Cavalier, M. Heller LAL, Orsay
	An insertion optics with a beta-star of at least 2600 m has been requested by the ATLAS experiment at the LHC. This is very far from the standard LHC physics optics and implies a significant reduction in the phase advance from this insertion corresponding to about half a unit in tune. We describe several alternatives how this could be integrated in overall LHC optics solutions with the possibility to inject, ramp and un-squeeze to the required very high beta.
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.
WEPP007	Crab Compensation for LHC Beams	2536
	R. Calaga BNL, Upton, Long Island, New York Y. Sun, R. Tomas, F. Zimmermann CERN, Geneva
	An R&D program to establish a road map for the installation of crab cavities in the LHC is rapidly advancing. Both local and global crab schemes are under investigation to develop cavities that will be compatible with LHC optics and meet aperture requirements. The design of a prototype TM110 cavity and pertinent RF requirements including impedance estimates and damping are discussed. Some alternate cavity designs are also explored. The required optics modifications to accommodate the crab cavities and some particle stability studies are presented.
WEPP008	Localizing Sources of Horizontal Orbit Oscillations at RHIC	2539
	R. Calaga, R. J. Michnoff, T. Satogata BNL, Upton, Long Island, New York
	Horizontal oscillations of the closed orbit at frequencies around 10Hz are observed at RHIC. These oscillations lead to beam beam offsets at the collision point, resulting in emittance growth and reduced luminosity. An approach to localize the sources of these vibrations using a special mode of RHIC turn-by-turn BPM data is presented. Data from the 2005-06 are analyzed to spatially resolve the location of the dominant sources.
WEPP009	Collimator Integration and Installation Example of One Object to be Installed in the LHC	2542
	K. Foraz, O. Aberle, R. W. Assmann, C. Bertone, R. Chamizo, S. Chemli, J.-P. Corso, F. Delsaux, J. L. Grenard, J. M. Jimenez, Y. Kadi, K. Kershaw, M. Lazzaroni, R. Perret, Th. Weiler CERN, Geneva J. Coupard IN2P3-CNRS, Orsay
	The collimation system is a vital part of the LHC project, protecting the accelerator against unavoidable regular and irregular beam loss. About 80 collimators will be installed in the machine before the first run. Two insertion regions are dedicated to collimation and these regions will be among the most radioactive in the LHC. The space available in the collimation regions is very restricted. It was therefore important to ensure that the 3-D integration of these areas of the LHC tunnel would allow straightforward installation of collimators and also exchange of collimators under the remote handling constraints imposed by high radiation levels. The paper describes the 3-D integration studies and verifications of the collimation regions combining the restricted space available, the dimensions of the different types of collimators and the space needed for transport and handling. The paper explains how installation has been planned and carried out taking into account the handling system and component availability.
WEPP010	Scheduling the Powering Tests	2545
	K. Foraz, E. Barbero-Soto, B. Bellesia, M. P. Casas Lino, C. Fernandez-Robles, M. Pojer, R. I. Saban, R. Schmidt, M. Solfaroli Camillocci, A. Vergara-Fernández CERN, Geneva
	The Large Hadron Collider is now entering in its final phase before receiving beam, and the activities at CERN between 2007 and 2008 have shifted from installation work to the commissioning of the technical systems (“hardware commissioning”). Due to the unprecedented complexity of this machine, all the systems are or will be tested as far as possible before the cool-down starts. Systems are firstly tested individually before being globally tested together. The architecture of LHC, which is partitioned into eight cryogenically and electrically independent sectors, allows the commissioning on a sector by sector basis. When a sector reaches nominal cryogenic conditions, commissioning of the magnet powering system to nominal current for all magnets can be performed. This paper briefly describes the different activities to be performed during the powering tests of the superconducting magnet system and presents the scheduling issues raised by co-activities as well as the management of resources.
WEPP011	Setup and Performance of RHIC for the 2008 Run with Deuteron and Gold Collisions	2548
	C. J. Gardner, N. P. Abreu, L. Ahrens, J. G. Alessi, M. Bai, D. S. Barton, J. Beebe-Wang, M. Blaskiewicz, J. M. Brennan, K. A. Brown, D. Bruno, J. J. Butler, P. Cameron, C. Carlson, R. Connolly, T. D'Ottavio, A. J. Della Penna, K. A. Drees, W. Fischer, W. Fu, G. Ganetis, J. W. Glenn, M. Harvey, T. Hayes, H. Huang, P. F. Ingrassia, J. Kewisch, R. C. Lee, V. Litvinenko, Y. Luo, W. W. MacKay, M. Mapes, G. J. Marr, A. Marusic, R. J. Michnoff, C. Montag, J. Morris, B. Oerter, F. C. Pilat, E. Pozdeyev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, T. Russo, P. Sampson, J. Sandberg, T. Satogata, C. Schultheiss, F. Severino, K. Smith, D. Steski, S. Tepikian, R. Than, P. Thieberger, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, K. Zeno, S. Y. Zhang BNL, Upton, Long Island, New York
	This year deuterons and gold ions were collided in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) for the first time since 2003. The setup and performance of the collider for this run is reviewed with a focus on improvements that have led to an order of magnitude increase in luminosity since the 2003 run.
WEPP012	Analysis of Optical Layouts for the Phase 1 Upgrade of the CERN Large Hadron Collider Insertion Regions	2551
	M. Giovannozzi, F. Borgnolutti, O. S. Brüning, U. Dorda, S. D. Fartoukh, W. Herr, M. Meddahi, E. Todesco, R. Tomas, F. Zimmermann CERN, Geneva R. de Maria EPFL, Lausanne
	In the framework of the studies for the upgrade of the insertions of the CERN Large Hadron Collider, four optical layouts were proposed with the aim of reducing the beta-function at the collision point down to 25 cm. The different candidate layouts are presented. Results from the studies performed on mechanical and dynamic aperture are summarized, together with the evaluation of beam-beam effects. Particular emphasis is given to the comparison of the optics performance, which led to retain two promising layouts for further investigation and development.
WEPP013	Increasing the Integrated Luminosity of SLHC by Levelling via the Crossing Angle	2554
	J.-P. Koutchouk, G. Sterbini CERN, Geneva K. Ohmi KEK, Ibaraki
	With an increase of luminosity by a factor of 10, the luminosity lifetime in an upgraded LHC would be limited to a few hours. Furthermore, schemes relying on stronger focusing and reduced beam current increase (which are intrisically less dangerous for machine protection) are penalized by a very short lifetime of around 2 hours. We show in this paper that the "early separation" scheme and/or crab cavities scheme lend themselves to a very efficient luminosity leveling scheme. It allows constant luminosity over many hours as well as a significant increase of integrated luminosity above the performance announced so far. This is achieved by adjusting the crossing angle rather than the beam size by means of a bump closed inside the experimental straight section, i.e. operationally simple. The initially large crossing angle reduces the beam-beam tune shift, allowing an increased beam current and higher performance for lower pile-up in the detector and lower energy deposition in the triplet. The impact of the required large Piwinski angle is investigated.
WEPP015	Experience with IBS-suppression Lattice in RHIC	2557
	V. Litvinenko, M. Bai, D. Bruno, P. Cameron, R. Connolly, A. J. Della Penna, K. A. Drees, A. V. Fedotov, G. Ganetis, L. T. Hoff, W. Louie, Y. Luo, N. Malitsky, G. J. Marr, A. Marusic, C. Montag, F. C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, S. Tepikian, D. Trbojevic, N. Tsoupas BNL, Upton, Long Island, New York
	An intra-beam scattering (IBS) is the limiting factor of the luminosity lifetime for RHIC operating with heavy ions. In order to suppress the IBS we designed and implemented new lattice with higher betatron tunes. This lattice had been developed during last three years and had been used for gold ions in yellow ring of the RHIC during d-Au part of the RHIC Run-8. The use of this lattice allowed both significant increases in the luminosity lifetime and the luminosity levels via reduction of beta-stars in the IPs. In this paper we report on the development, the tests and the performance of IBS-suppression lattice in RHIC, including the resulting increases in the peak and the average luminosity. We also report on our plans for future steps with the IBS suppression.
WEPP018	Operational Experience with a Near-integer Working Point at RHIC	2563
	C. Montag, M. Bai, J. Beebe-Wang, W. Fischer, Y. Luo, N. Malitsky, T. Roser, T. Satogata, S. Tepikian BNL, Upton, Long Island, New York
	During the RHIC polarized proton run in FY 2006 it became evident that the luminosity performance is limited by the beam-beam effect. With a working point between 2/3 and 7/10, and the necessity to mirror the tunes of the two RHIC rings at the diagonal, the beam with a horizontal tune closest to 2/3 showed poor lifetime. To overcome this limitation, a near-integer working point has been proposed. Tracking studies performed at both working points showed a larger dynamic aperture near the integer tune than above 2/3. In Run-8, this new working point was commissioned in one ring of RHIC, while the other ring was operated at the same working point as in Run-6. In this paper we report the commissioning process and operational experience with this new working point.
WEPP019	RHIC Polarized Proton Performance in Run-8	2566
	C. Montag, N. P. Abreu, L. Ahrens, M. Bai, D. S. Barton, A. Bazilevsky, J. Beebe-Wang, M. Blaskiewicz, J. M. Brennan, K. A. Brown, D. Bruno, G. Bunce, R. Calaga, P. Cameron, R. Connolly, T. D'Ottavio, K. A. Drees, A. V. Fedotov, W. Fischer, G. Ganetis, C. J. Gardner, J. W. Glenn, T. Hayes, H. Huang, P. F. Ingrassia, A. Kayran, J. Kewisch, R. C. Lee, V. Litvinenko, A. U. Luccio, Y. Luo, W. W. MacKay, Y. Makdisi, N. Malitsky, G. J. Marr, A. Marusic, R. J. Michnoff, J. Morris, B. Oerter, H. Okada, F. C. Pilat, P. H. Pile, G. Robert-Demolaize, T. Roser, T. Russo, T. Satogata, C. Schultheiss, M. Sivertz, K. Smith, S. Tepikian, D. Trbojevic, N. Tsoupas, J. E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S. Y. Zhang BNL, Upton, Long Island, New York
	During Run-8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin-polarized proton beams at two interaction regions. Helical spin rotators at these two interaction regions were used to control the spin orientation of both beams at the collision points. Physics data were taken with different orientations of the beam polarization. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run-8.
WEPP024	Non-linear Correction Schemes for the Phase 1 LHC Insertion Region Upgrade and Dynamic Aperture Studies	2569
	R. Tomas, M. Giovannozzi, R. de Maria CERN, Geneva
	The Phase 1 LHC Interaction Region (IR) upgrade aims at increasing the machine luminosity essentially by reducing the beam size at the Interaction Point (IP). This requires a total redesign of the full IR. A large set of options have been proposed with conceptually different designs. This paper reports on a general approach for the compensation of the multipolar errors of the IR magnets in the design phase. The goal is to use the same correction approach for the different designs. The correction algorithm is based on the computation of the IR transfer map. Its performance is tested using the dynamic aperture as figure of merit.
WEPP025	Optics Correction in the LHC	2572
	R. Tomas, M. Aiba, G. Vanbavinckhove CERN, Geneva R. Calaga BNL, Upton, Long Island, New York A. Morita KEK, Ibaraki
	Optics correction in the LHC is challenged by the tight aperture constrains and the demand of a highly performing BPM system. To guarantee that the LHC optics remains within a maximum allowable beta-beating of 20% several methods are being investigated through computer simulations and experiments at existing hadron machines. A software package to consolidate the implementation of the various techniques during LHC operation is underway (or nearing completion)
WEPP026	Reliable Operation of the AC Dipole in the LHC	2575
	R. Tomas, S. D. Fartoukh, J. Serrano CERN, Geneva
	The AC dipole in the LHC will not only provide transverse oscillations without emittance growth but also with a safety guarantee. These two features are due to the adiabaticity of the excitation. However chromaticity and non-linear fields spoil this adiabaticity. This paper assesses the margins of the relevant parameters for a reliable and safe operation of AC dipoles in the LHC.
WEPP029	Project of the Nuclotron-based Ion Collider Facility (NICA) at JINR	2581
	G. V. Trubnikov, N. N. Agapov, V. Alexandrov, A. V. Butenko, E. E. Donets, A. V. Eliseev, A. Govorov, V. Kekelidze, H. G. Khodzhibagiyan, V. Kobets, A. D. Kovalenko, O. S. Kozlov, A. Kuznetsov, I. N. Meshkov, V. A. Mikhaylov, V. Monchinsky, V. Shevtsov, A. O. Sidorin, A. N. Sissakian, A. V. Smirnov, A. Sorin, V. Toneev, V. Volkov, V. Zhabitsky JINR, Dubna, Moscow Region O. I. Brovko, I. Issinsky JINR/LHE, Moscow
	The Nuclotron-based Ion Collider fAcility (NICA) is the new accelerator complex being constructed at JINR aimed to provide collider experiments with heavy ions up to uranium at maximum energy (center of mass) equal to 9 GeV/u. It includes new 6 Mev/u linac, 440 MeV/u booster, upgraded SC synchrotron Nuclotron and collider consisting of two SC rings, which provide average luminosity of 1027cm-2s-1. General goal of the project is to start in the coming 5-7 years experimental study of hot and dense strongly interacting QCD matter and search for possible manifestation of signs of the mixed phase and critical endpoint in heavy ion collisions. The NICA and the Multi Purpose Detector (MPD) are proposed for these purposes. Accelerator complex NICA is being built on the experience and technological developments at the Nuclotron facility and incorporates new technological concepts. The new facility will allow also an effective acceleration of light ions to the Nuclotron maximum energy and an increase of intensity of polarized deuteron beams up to the level above 1010 particles/cycle. The scheme of the facility, its operation scenario and beam dynamics are presented in the report.
WEPP030	LHC Luminosity Upgrade: Protecting Insertion Region Magnets from Collision Debris	2584
	E. Y. Wildner, F. Cerutti, A. Ferrari, M. Mauri, A. Mereghetti CERN, Geneva
	The Large Hadron Collider built at CERN now enters a starting-up phase where with the present design luminosities up to 1034 cm-2 s-1 will be reached after the running in phase. A possible upgrading of the machine to luminosities up to 1035 cm-2 s-1 requires a completely new insertion region design, and will be implemented in essentially two phases. The energy from collision debris is deposited in the insertion regions and in particular in the superconducting magnet coils with a possible risk of quench. We describe here how to protect the interaction region magnets against this irradiation to keep the energy deposition below critical values estimated for safe operation. The constraint is to keep the absorber size as small as possible to leave most of the magnet aperture available for the beam. This can be done by choosing a suitable material and design minimizing the load on the cryogenic system. We will describe a proposal of a design for the phase I upgrade lay-out (i.e., luminosities up to 2.5 1034 cm-2 s-1).
WEPP031	Energy Deposited in the High Luminosity Inner Triplets of the LHC by Collision Debris	2587
	E. Y. Wildner, F. Cerutti, A. Ferrari, C. Hoa, J.-P. Koutchouk CERN, Geneva F. Broggi INFN/LASA, Segrate (MI) N. V. Mokhov Fermilab, Batavia, Illinois
	The 14 TeV center of mass proton-proton collisions in the LHC produce not only interesting events for physics but also debris ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of the deposited heat, that has to be transferred to the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC baseline are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the comparison and consolidation of the calculations, a dedicated study of a simplified model has been made, showing satisfactory agreement.
WEPP032	Parametric Study of Energy Deposition in the LHC Inner Triplet for the Phase 1 Upgrade	2590
	E. Y. Wildner, F. Borgnolutti, F. Cerutti, M. Mauri, A. Mereghetti, E. Todesco CERN, Geneva
	To be able to make a global parametric analysis and to have some basic understanding of the influence of critical parameters, scaling laws may be of help. For the design of the LHC collision insertion regions, one of the critical parameters is the energy deposited in the insertion superconducting magnet coils, to avoid magnet quench, too heavy load on the cryogenic system, and degradation of the superconductor due to radiation. The influence on energy deposition of some key parameters for magnet design, such as the magnet apertures, the magnet lengths and positions, has been studied for some specified optical beta-value at the collision point.
WEPP034	Study of Beam-beam effect at various collision scheme in LHC	2593
	K. Ohmi KEK, Ibaraki
	LHC is designed as two major collision points with finite crossing angle of 140μrad (half). The Piwinski angle is 0.4 for the design. Upgrade plans have been studied to increase the luminosity 10 times. Large Piwinski angle scheme is one of the option for the upgrade. The one turn map with the two beam-beam interactions can be expanded by Taylor series. Analyzing the one turn map gives information of resonance behavior of the beam-beam interactions. We discuss the one turn map for the design LHC and upgrade scheme.
FRXAGM01	RHIC and its Upgrade Programs	3723
	T. Roser BNL, Upton, Long Island, New York
	As the first hadron accelerator and collider consisting of two independent superconducting rings RHIC has operated with a wide range of beam energies and particle species. After a brief review of the achieved performance the presentation will give an overview of the plans, challenges and status of machine upgrades, that range from a new heavy ion pre-injector and beam cooling at 100 GeV to a high luminosity electron-ion collider.
	Slides