IPAC2013 - List of Keywords (luminosity)

Paper	Title	Other Keywords	Page
MOYAB101	The First Years of LHC Operation for Luminosity Production	proton, injection, emittance, feedback	6
	M. Lamont CERN, Geneva, Switzerland
	A summary of the first 3 years of LHC operation is presented with a discussion on the performance ramp-up, operation efficiencies and system reliability. The main contributory factors to peak and integrated luminosity performance are outlined.
	Slides MOYAB101 [12.139 MB]

MOZB201	Overview of the LHeC Design Study at CERN	lepton, linac, proton, electron	40
	O.S. Brüning CERN, Geneva, Switzerland
	The LHeC is a potential future lepton-hadron collider project at CERN based on the existing LHC infrastructure. The presentation highlights the main results of the recently published conceptual design report, including the findings of an international review committee that evaluated it. The presentation outlines the planed future studies and R&D activities for the next years.
	Slides MOZB201 [11.894 MB]

MOZB202	The First Long Shutdown (LS1) for the LHC	dipole, ion, vacuum, radiation	44
	F. Bordry, S. Baird, K. Foraz, A.-L. Perrot, R.I. Saban, J.Ph. G. L. Tock CERN, Geneva, Switzerland
	The LHC has been delivering data to the physics experiments since the first collisions in 2009. The first long shutdown (LS1), which started on 14 February 2013, was triggered by the need to consolidate the magnet interconnections so as to allow the LHC to operate at the design energy of 14 TeV in the centre-of-mass. It has now become a major shutdown which, in addition, includes other repairs, consolidation, upgrades and cabling across the whole accelerator complex and the associated experimental facilities. LS1 will see a massive programme of maintenance for the LHC and its injectors in the wake of more than three years of operation without the long winter shutdowns that were the norm in the past. The main driving effort will be the consolidation of the 10,170 high-current splices between the superconducting magnets. The presentation describes first the preparation phase with the prioritisation of the activities, the building of the teams and the detailed planning of the operation. Then, it gives the status after 3 months and the restart plans for all CERN accelerators. First lessons learnt for the 2nd long shutdown (LS2) will conclude the presentation.
	Slides MOZB202 [13.675 MB]

MOODB201	Proton-nucleus Collisions in the LHC	injection, proton, heavy-ion, ion	49
	J.M. Jowett, R. Alemany-Fernandez, P. Baudrenghien, D. Jacquet, M. Lamont, D. Manglunki, S. Redaelli, M. Sapinski, M. Schaumann, M. Solfaroli Camillocci, R. Tomás, J.A. Uythoven, D. Valuch, R. Versteegen, J. Wenninger CERN, Geneva, Switzerland
	Following the high integrated luminosity accumulated in the first two Pb-Pb collision runs in 2010 and 2011, the LHC heavy-ion physics community requested a first run with p-Pb collisions. This almost unprecedented mode of collider operation was not foreseen in the baseline design of the LHC whose two-in-one magnet design imposed equal rigidity and, hence, unequal revolution frequencies, during injection and ramp. Nevertheless, after a successful pilot physics fill in 2012, the LHC provided 31 nb^-1 of p-Pb luminosity per experiment, at an energy of 5.02 TeV per colliding nucleon pair, with several variations of the operating conditions, in early 2013. Together with a companion p-p run at 2.76 TeV, this was the last physics before the present long shutdown. We summarise the beam physics, operational adaptations and strategy that resulted in extremely rapid commissioning. Finally, we give an account of the progress of the run and provide an analysis of the performance.
	Slides MOODB201 [6.547 MB]

MOPME004	Fast Luminosity Monitoring using Diamond Sensors for Super Flavour Factories	scattering, photon, electron, positron	473
	C. Rimbault, P. Bambade LAL, Orsay, France
	Super flavour factories aim to reach very high luminosities thanks to a new concept whereby the ultra-low emittance beams collide with a large crossing angle. Fast luminosity measurements are needed as input to luminosity optimization and feedback in the presence of dynamic imperfections. The required small relative precision can be reached exploiting the very large cross section of the radiative Bhabha process at zero photon scattering angle. The instrumental technique selected to sustain the large particle fluxes is based on diamond sensors to be positioned via moveable stages immediately outside the beam pipe, at locations chosen to minimize the contamination from other particle loss mechanisms.

MOPME071	Characterisation of Si Detectors for use at 2 Kelvin	proton, cryogenics, radiation, superconducting-magnet	643
	M.R. Bartosik, C. Arregui Rementeria, B. Dehning, T. Eisel, C. Kurfuerst, M. Sapinski CERN, Geneva, Switzerland V. Eremin, E. Verbitskaya IOFFE, St. Petersburg, Russia
	Funding: This research project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community’s Seventh Framework Programme under contract nr PITN-GA-2011-289485-OPAC. It is expected that the luminosity of the Large Hadron Collider (LHC) will be bounded in the future by the beam loss limits of the superconducting magnets. To protect the superconducting magnets of the high luminosity insertions an optimal detection of the energy deposition by the shower of beam particles is necessary. Therefore beam Loss Monitors (BLM) need to be placed close to the particle impact location in the cold mass of the magnets where they should operate in superfluid helium at 1.9 Kelvin. To choose optimal detectors n-type silicon wafers have been examined at superfluid helium temperature whilst under irradiation from a high intensity proton beam. The radiation hardness and leakage current of these detectors were found to be significantly improved at 1.9 Kelvin when compared to their operation at room temperature.

MOPWO010	Machine Protection Studies for a Crab Cavity in the LHC	simulation, beam-losses, cavity, collimation	906
	B. Yee-Rendon, R. Lopez-Fernandez CINVESTAV, Mexico City, Mexico T. Baer, J. Barranco, R. Calaga, A. Marsili, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland
	Funding: US-LARP and CONACYT Crab cavities (CCs) apply a transverse kick that rotate the bunches so as to have a head-on collision at the interaction point (IP). Such cavities were successfully used to improve the luminosity of KEKB. They are also a key ingredient of the HL-LHC project to increase the luminosity of the LHC. As CCs can rapidly change the particle trajectories, machine protection studies are required to assess the beam losses due to fast CC failures. In this paper, we discuss the effect of rapid voltage or phase changes in a CC for the HL-LHC layout using measured beam distributions from the present LHC.

MOPWO020	Space Charge Dominated Envelope Dynamics using GPUs	space-charge, simulation, controls, focusing	924
	N.V. Kulabukhova St. Petersburg State University, St. Petersburg, Russia
	High power accelerator facilities lead to necessity to consider space charge forces. It is therefore important to study the space charge dynamics in the corresponding channels. To represent the space charge forces of the beam we have developed special software based on some analytical models for space charge distributions. Because calculations for space charge dynamics become extremely time consuming, we use a special algorithm for predictor-corrector method for evaluation scheme for beam map evaluation including the space charge forces. This method allows us to evaluate the map along the references trajectory and to create the beam envelope dynamics. The corresponding computer codes are realized using CUDA implementation of maps for particle dynamics. Some numerical results for different types of the beam channels are discussed. The survey of advantages and disadvantages of using different methods of parallelization and some parallel approaches will be done.

MOPWO032	SPS Scraping and LHC Transverse Tails	injection, emittance, beam-losses, controls	957
	L.N. Drøsdal, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, O. Mete, B. Salvachua, G. Valentino, E. Veyrunes CERN, Geneva, Switzerland
	All high-intensity LHC beams have to be scraped before extraction from the SPS to remove the non-Gaussian transverse tails of the particle distributions. The tail particles would otherwise cause unacceptably high losses during injection or other phases of the LHC cycle. Studies have been carried out to quantify the scraping using injection losses and emittance measurements from wire scanners as diagnostics. Beams scraped in the SPS were scraped again in the LHC with collimators to investigate possible tail repopulation. The results of these studies will be presented in this paper.

MOPWO034	Energy Deposition Studies for the Upgrade of the LHC Injection Lines	injection, proton, optics, quadrupole	963
	A. Mereghetti, O. Aberle, F. Cerutti, B. Goddard, V. Kain, F.L. Maciariello, M. Meddahi CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom E. Gianfelice-Wendt Fermilab, Batavia, USA
	The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Given the challenging beam intensities and emittances, a review of the existing beam-intercepting devices is on-going, in order to assess heat loads and consequent thermo-mechanical stresses. Moreover, the exposure of downstream elements to induced shower radiation is assessed. The study is intended to spot possible issues and contribute to the definition of viable design and layout solutions.

MOPWO040	Analysis of Failures of the LHC Collimators during the 2010-2013 Operation	collimation, injection, controls, insertion	981
	S. Redaelli, A. Masi CERN, Geneva, Switzerland
	The LHC collimation system must be available in all phases of the machine operation in order to handle the high stored beam energies. The system availability is therefore crucial to achieve an efficient LHC operation. The collimation system has proved to work reliably in the first years of LHC operation, with total stored energies up to 140 MJ. The impact on the machine availability has been limited. The analysis of collimation system availability and the failure rate in the years 2012-2012 is reviewed with the aim to identify possible further improvements for the future.

MOPWO041	Simulations and Measurements of Physics Debris Losses at the 4 TeV LHC	simulation, proton, background, dipole	984
	A. Marsili, R. Bruce, F. Cerutti, S. Redaelli CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Simulations of energy deposition from the physics debris are normally done with shower simulation tools like FLUKA. Tracking tools like SixTrack allow faster simulations that open the possibility to study parametrically and optimize different layouts. In this paper, the results of FLUKA and SixTrack simulations are compared to beam measurements done for different collimator settings at 4 TeV, with p-p luminosities up to 7·10³³ cm^-2s⁻¹.

MOPWO042	Simulations of Collimation Cleaning Performance with HL-LHC Optics	optics, simulation, collimation, proton	987
	A. Marsili, R. Bruce, R. De Maria, S.D. Fartoukh, S. Redaelli CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The upgrade of the LHC from the current set-up to high luminosity performances will provide new challenges for the protection of the machine. The different optics considered might create new needs for collimation, and require new collimation locations. In order to evaluate the cleaning performances of the collimation system, different halo cleaning simulations were performed with the particle tracking code SixTrack. This paper presents the cleaning performance simulation results for the high luminosity Achromatic Telescopic Squeeze optics considered as baseline for the HL-LHC. The new limitations observed and possible solutions are discussed.

MOPWO047	Studies of Thermal Loads on Collimators for HL-LHC Optics in case of Fast Losses	optics, proton, kicker, collimation	999
	L. Lari, R. Bruce, F. Cerutti CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The new layouts for the HL-LHC pose new challenges in terms of proton loads on the collimators around the ring, in particular for the ones of in experimental regions that become critical with squeeze optics. New layouts are under consideration, which foresee updated collimation schemes. Simulations of halo loads for in case of fast failures have been setup with SixTrack in order to determine beam loss distributions for realistic error scenarios. The particle tracking studies might then be interfaced to tools like FLUKA to evaluate the thermal loads on collimators in case of failures. In this paper, the preliminary studies performed for the baseline HL-LHC optics layouts are presented.

MOPWO049	Lifetime Analysis at High Intensity Colliders Applied to the LHC	proton, collider, collimation, beam-losses	1005
	B. Salvachua, R.W. Aßmann, R. Bruce, F. Burkart, S. Redaelli, G. Valentino, D. Wollmann CERN, Geneva, Switzerland G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The beam lifetime is one of the main parameters to define the performance of a collider. In a super-conducting machine like the LHC, the lifetime determines the intensity reach for a given collimation cleaning. The beam lifetime can be calculated from the direct measurement of beam current. However, due to the noise in the beam current signal only an average lifetime over several seconds can be calculated. We propose here an alternative method, which uses the signal of the beam loss monitors in the vicinity of the primary collimators to get the instantaneous beam lifetime at the collimators. In this paper we compare the lifetime from the two methods and investigate the minimum lifetime over the LHC cycle for all the physics fills in 2011 and 2012. These data provide a reference for estimates of performance reach from collimator cleaning.

MOPWO051	Estimate of Warm Magnets Lifetime in the Betatron and Momentum Cleaning Insertions of the LHC	betatron, insertion, collimation, radiation	1011
	B. Salvachua, R. Bruce, M. Brugger, F. Cerutti, S. Redaelli CERN, Geneva, Switzerland
	The CERN LHC collimation system is designed to perform momentum and betatron cleaning in different insertions, respectively IR3 and IR7. The insertions are not perfectly decoupled because the dispersion in IR7 is not null and the beta function in IR3 is not zero. The detailed sharing of losses between the two insertions depends on the relative collimator settings as observed by the change between 2011 and 2012 LHC operation. In this report, using the beam loss measurements at the primary collimators of IR3 and IR7, the total BLM losses in the two insertions are calculated and compared to each other. These studies are also used to quantify the total dose to warm magnets in those IRs with the aim to understand better their lifetime and the implications of the radiation to electronics. This will be of particular importance in view of LHC operating at nominal performance after several years of operation.

MOPWO054	The LHeC as a Higgs Boson Factory	linac, factory, lepton, electron	1017
	F. Zimmermann, O.S. Brüning CERN, Geneva, Switzerland M. Klein The University of Liverpool, Liverpool, United Kingdom
	The LHeC is designed to collide a new 60 GeV energy electron beam, from a 3-pass ERL, with the 7 TeV energy LHC proton beam. At the present target ep luminosity of 10³³cm^-2s^-1, the LHeC would produce a few 1000 Higgs bosons per year, allowing for precision coupling measurements, especially of the H –> b bbar decay in charged current deep inelastic scattering (ep –> nu H X). With a significant increase of the luminosity, rarer channels become accessible, as the charm decay. Here such an increase, to the level of 10³⁴cm^-2s^-1 or even beyond, is considered from a combination of improvements, namely with a smaller proton beam emittance, with a further reduction of the proton IP beta function, an increase of the proton bunch intensity and with doubling the lepton beam current, compared to the canonical values assumed in the CDR.

MOPWO080	GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders	simulation, collider, electron, damping	1064
	Y. Roblin, V.S. Morozov, B. Terzić JLAB, Newport News, Virginia, USA M. Aturban, D. Ranjan, M. Zubair ODU CS, Norfolk, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.

TUYB101	Progress in Super B-Factories	emittance, linac, positron, alignment	1096
	K. Akai KEK, Ibaraki, Japan
	The upgrade of B-Factories to Super B-Factories, which will search for new physics beyond the Standard Model, opens the way for new luminosity frontier. The status of Super B-Factories will be reported.
	Slides TUYB101 [42.300 MB]

TUYB103	Status and Plans for the Polarized Hadron Collider at RHIC	polarization, proton, resonance, acceleration	1106
	M. Bai, L. A. Ahrens, E.C. Aschenauer, G. Atoian, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, O. Eyser, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, A.I. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. As the world’s only high energy polarized proton collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been providing collisions of polarized proton beams at beam energy from 100~GeV to 255~GeV for the past decade to explore the proton spin structure as well as other spin dependent measurements. With the help of two Siberian Snakes per accelerator plus outstanding beam control, beam polarization is preserved up to 100~GeV. About 10% polarization loss has been observed during the acceleration between 100~GeV and 255~GeV due to several strong depolarizing resonances. Moderate polarization loss was also observed during a typical 8 hour physics store. This presentation will overview the achieved performance of RHIC, both polarization as well as luminosity. The plan for providing high energy polarized He-3 collisions at RHIC will also be covered. This work is on behalf of RHIC team.
	Slides TUYB103 [12.854 MB]

TUPFI001	High Luminosity LHC Matching Section Layout vs Crab Cavity Voltage	optics, cavity, injection, quadrupole	1328
	B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Chancé, J. Payet CEA/DSM/IRFU, France R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland
	Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan. In the framework of the HL-LHC Upgrade project we present a new possible variant for the layout of the LHC matching section located in the high luminosity insertions. This layout is optimized to reduce the demand on the voltage of the crab cavities, while substantially improving the optics squeeze-ability, both in ATS [1] and non-ATS mode. These new layout will be described in details together with its performance figures in terms of mechanical acceptance, chromatic properties and optics flexibility. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI002	Electron Cloud and Scrubbing Studies for the LHC	injection, electron, emittance, dipole	1331
	G. Iadarola Naples University Federico II, Science and Technology Pole, Napoli, Italy G. Arduini, V. Baglin, H. Bartosik, C.O. Domínguez, J. Esteban Müller, G. Iadarola, G. Rumolo, E.N. Shaposhnikova, L.J. Tavian, F. Zimmermann CERN, Geneva, Switzerland C.O. Domínguez EPFL, Lausanne, Switzerland G.H.I. Maury Cuna CINVESTAV, Mexico City, Mexico
	Electron cloud build-up resulting from beam-induced multipacting is one of the major limitations for the operation of the LHC with beams with close bunch spacing. Electron clouds induce unwanted pressure rise, heat loads on the beam screens of the superconducting magnets and beam instabilities. Operation with bunch spacing of 50 ns in 2011 and 2012 has required decreasing the Secondary Electron Yield of the beam screens below the multipacting threshold for beams with this bunch spacing. This was achieved by continuous electron bombardment induced by operating the machine with high intensity beams with 50 and 25 ns spacing during dedicated periods at injection energy (450 GeV) and at top energy (3.5 and 4 TeV). The evolution of the Secondary Electron Yield during these periods, at different sections of the machine, can be estimated by pressure, heat load and by bunch-by-bunch RF stable phase measurements. The experimental information on the scrubbing process will be discussed and a possible “scrubbing strategy” to allow the operation with 50ns and 25ns beams after the Long Shutdown in 2013-2014 will be presented.

TUPFI009	NICA project at JINR	ion, collider, booster, heavy-ion	1343
	G.V. Trubnikov, N.N. Agapov, E.D. Donets, V.V. Fimushkin, E.V. Gorbachev, A. Govorov, E.V. Ivanov, V. Karpinsky, V.D. Kekelidze, H.G. Khodzhibagiyan, A.D. Kovalenko, K.A. Levterov, V.A. Matveev, I.N. Meshkov, V.A. Mikhailov, V. Monchinsky, S. Romanov, N. Shurkhno, A.O. Sidorin, V. Slepnev, A.V. Smirnov, A. Sorin, N.D. Topilin JINR, Dubna, Moscow Region, Russia O.I. Brovko, A.V. Butenko, E.E. Donets, A.V. Eliseev, O.S. Kozlov, A.V. Philippov, N.V. Semin, A. Tuzikov, V. Volkov JINR/VBLHEP, Moscow, Russia
	The Nuclotron-based Ion Collider fAcility (NICA) is a new accelerator complex being constructed at JINR aimed to provide the collider experiments with ion-ion (Au⁷⁹⁺) and ion-proton collisions at the energy range of 1-4.5 GeV/n and also the collisions of polarized proton-proton and deuteron-deuteron beams. Progress in the project realization is reported.

TUPFI010	The LHCb Online Luminosity Control and Monitoring	controls, target, dipole, proton	1346
	R. Alemany-Fernandez, F. Follin, R. Jacobsson CERN, Geneva, Switzerland
	The online luminosity control consists of an automatic slow real-time feedback system controlled by specific LHCb software, which communicates directly with a LHC software application. The LHC application drives a set of corrector magnets to adjust the transversal beam overlap at the LHCb interaction point in order to keep the instantaneous luminosity aligned to the target luminosity provided by the experiment. It was proposed and tested first in July 2010, and it has been in routine operation during the first two years of physics luminosity data taking, 2011 and 2012. This paper describes the operational performance of the LHCb experiment and the LHC accelerator during the luminosity control of the experiment, the accounting of the recorded luminosity and dead time of the detector, and analyses the beam stability during the adjustment of the transverse beam overlap at the interaction point.

TUPFI011	Study and Operational Implementation of a Tilted Crossing Angle in LHCb	dipole, beam-losses, controls, monitoring	1349
	R. Alemany-Fernandez, F. Follin, B.J. Holzer, D. Jacquet, R. Versteegen, J. Wenninger CERN, Geneva, Switzerland
	The current crossing angle scheme at LHCb interaction point (horizontal crossing angle and vertical beam separation) prohibits the use of the LHCb dipole positive polarity for 25 ns bunch spacing operation since the beam separation at the first parasitic encounter is very small inducing unwanted beam encounters. To overcome this limitation a different crossing angle scheme was proposed in 2007 by W. Herr and Y. Papaphilippou. The new schema implies a vertical external crossing angle that together with the horizontal internal crossing angle, from the LHCb dipole and its three compensator magnets, defines a new tilted crossing and separation plane providing enough beam separation at the parasitic encounters. This paper summarizes the feasibility study of the new crossing scheme, the implementation in routine operation and analyzes the beam stability during the building up of the tilted crossing plane.

TUPFI012	HL-LHC: Integrated Luminosity and Availability	target, simulation, collider, hadron	1352
	A. Apollonio, M. Jonker, R. Schmidt, B. Todd, S. Wagner, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	The objective of LHC operation is to optimise the output for particle physics by maximising the integrated luminosity. An important constraint comes from the event pile–up for one bunch crossing that should not exceed 140 events per bunch crossing. With bunches every 25 ns the luminosity for data taking of the experiments should therefore not exceed 5*10³⁴ s⁻¹cm^-2. For the optimisation of the integrated luminosity it is planned to design HL-LHC for much higher luminosity than acceptable for the experiments and to limit the initial luminosity by operating with larger beam size at the collision points. During the fill, the beam size will be slowly reduced to keep the luminosity constant. The gain from luminosity levelling depends on the average length of the fills. Today, with the LHC operating at 4 TeV, most fills are terminated due to equipment failures, resulting in an average fill length of about 5 h. In this paper we discuss the expected integrated luminosity for HL-LHC as a function of fill length and time between fills, depending on the expected MTBF of the LHC systems with HL-LHC parameters. We derive an availability target for HL-LHC and discuss steps to achieve this.

TUPFI015	Study of the IR2 and IR8 Squeezeability for HL-LHC Upgrade	optics, injection, quadrupole, insertion	1361
	A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia R. De Maria CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The paper presents the results of the study of different optics configurations which allow to reach smaller beta functions at the IP2 and IP8 in the framework of the HL-LHC project. The variants at collision energies must be compatible with the ATS* scheme which provides small beta function at the IP1 and IP5 or provide low beta function for Alice and LHCb during ion operatations. The ones at injection must satisfy injection transfer lines and aperture constraints. The final goal is to find the overlap between the phase advances of all the configuration for IR2 and IR8 respectively, in order to mainting the LHC working point without rematching the remaining insertions. * S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI016	Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy	target, quadrupole, lattice, dynamic-aperture	1364
	Y. Nosochkov, Y. Cai, M.-H. Wang SLAC, Menlo Park, California, USA R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515. For the high luminosity upgrade of the LHC (HL-LHC), the beta functions at two interaction points (IP) will be significantly reduced compared to the nominal LHC lattice. This will result in much higher peak beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The field error tolerances in these magnets must satisfy the required acceptable DA while being reasonably close to realistically achievable field quality. Evaluation of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gradient of 123 T/m and IP collision beta functions of 15 cm in both planes. Dynamic aperture calculations were performed using SixTrack. Details of the optimization of the IT field errors are presented along with corrections to achieve the field quality specifications. S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI021	FLUKA Energy Deposition Studies for the HL-LHC	quadrupole, radiation, shielding, optics	1379
	L.S. Esposito, F. Cerutti, E. Todesco CERN, Geneva, Switzerland
	The LHC upgrade, planned in about ten years from now, is envisaged to accumulate up to 3000 fb-1 integrated luminosity by running at a peak luminosity of 5 x 10³⁴ cm^-2 s⁻¹. In order to reach such an ambitious goal, the high luminosity insertions need a major redesign implying a 150 mm aperture low-beta Inner Triplet, a superconducting D1 and new quadrupoles in the Matching Section. Energy deposition studies show that degradation of the coil insulator represents the most challenging issue from the radiation impact point of view. We propose a suitable shielding consisting of a beam screen with several mm tungsten absorbers at mid-planes to guarantee not to exceed a few ten MGys. This will also allow a good margin with respect to the risk of radiation induced quenches. O. Brüning, L. Rossi, "High Luminosity Large Hadron Collider: A description for the European Strategy Preparatory Group," CERN ATS 2012-236.*

TUPFI022	Power Load from Collision Debris on the LHC Point 8 Insertion Magnets Implied by the LHCb Luminosity Increase	dipole, quadrupole, proton, optics	1382
	L.S. Esposito, F. Cerutti, A. Lechner, A. Mereghetti, A.A. Patapenka, V. Vlachoudis CERN, Geneva, Switzerland A. Mereghetti UMAN, Manchester, United Kingdom A.A. Patapenka JIPNR-Sosny NASB, Minsk, Belarus
	LHCb is aiming to upgrade its goal peak luminosity up to a value of 2 10³³ cm^-2 s⁻¹ after LS2. We investigate the collision debris impact on the machine elements by extensive FLUKA simulations, showing that the present machine layout is substantially compatible with such a luminosity goal. In particular the installation of a TAS (Target Absorber ofSecondaries, installed in front of the final focus Q1-Q3 quadrupole triplet in the LHC high luminosity insertions) turns out not to be necessary on the basis of the expected peak power deposition in the Q1 superconducting coils. A warm protection may be desirable to further reduce heat load and dose on the D2 recombination dipole, due to the absence of the TAN (Target Absorber of Neutrals, present in Point 1 and 5).

TUPFI023	Optics Design and Lattice Optimisation for the HL-LHC	optics, quadrupole, lattice, cavity	1385
	B.J. Holzer, R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson UMAN, Manchester, United Kingdom A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia A. Chancé CEA, Gif-sur-Yvette, France B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Faus-Golfe, J. Resta IFIC, Valencia, Spain K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom C. Milardi INFN/LNF, Frascati (Roma), Italy J. Payet CEA/DSM/IRFU, France A. Wolski The University of Liverpool, Liverpool, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Cap. Spec. Progr, Grant Agreement 284404. The luminosity upgrade project of the LHC collider at CERN is based on a strong focusing scheme to reach smallest beam sizes at the collision points. Depending on the available magnet technology (Nb3Sn or NbTi) a number of beam optics has been developed to define the specifications for the new super conducting quadrupoles. In the context of the optics matching new issues have been addressed and new concepts have been used: Quadrupole strength flexibility and chromatic corrections have been studied, as well as the influence of quadrupole fringe fields. The lattice has been optimised including the needs of the foreseen crab cavities and the transition between injection and low β optics had to guarantee smooth gradient changes over a wide range of β* values. Tolerances on misalignments and power converter ripple have been re-evaluated. Finally the combination of the quadrupole strengths in the high luminosity matching sections with those in the neighboring sectors is explained, a key concept of the ATS to reach smallest β* values. This paper presents the results obtained within the HiLumi collaboration Task 2.2 and summarises the main parameters of the project.

TUPFI024	Influence of the Ats Optics on Intra-Beam Scattering for HL-LHC	optics, emittance, simulation, collider	1388
	M. Schaumann, R. Bruce, J.M. Jowett CERN, Geneva, Switzerland M. Schaumann RWTH, Aachen, Germany
	In the future High Luminosity (HL-)LHC the influence of intra-beam scattering (IBS) will be stronger than in the present LHC, because of higher bunch intensity, small emittance and new optics. The new ATS-optics scheme modifies the lattice in the arcs around the main interaction points (IP) to provide β* values as small as 0.15m in the IP, however those modifications affect the IBS growth rates. In this paper proton IBS emittance growth rates are calculated with MADX and the Collider Time Evolution (CTE) program for two ATS-optics versions, different settings of the crossing angles and required corrections and various beam conditions at injection (450 GeV) and collision (7 TeV) energy. CTE simulations of the expected luminosity, intensity, emittance and bunch length evolution during fills are also presented

TUPFI025	Bunch-by-Bunch Analysis of the LHC Heavy-Ion Luminosity	injection, emittance, simulation, ion	1391
	M. Schaumann, J.M. Jowett CERN, Geneva, Switzerland
	After the first run in 2010, the LHC continued its heavy-ion operation with collisions of lead nuclei in late 2011. The beam dynamics of those high intensity lead beams are strongly influenced by intra-beam scattering (IBS), especially on the injection plateau. Each batch injected from the SPS spends a different time at injection, introducing significant changes from batch to batch. Within the batches there is an even larger spread imprinted by the SPS injection plateau. This results in a spread of the luminosity produced in each bunch crossing. The particle losses during collisions are dominated by nuclear electromagnetic processes, leading to a non-exponential intensity decay during the fill and short luminosity lifetime at 3.5 Z TeV. The luminosity, emittance, intensity and bunch length evolution of the 2011 run was analysed bunch-by-bunch and compared with simulations. Based on this analysis, estimates of the potential luminosity performance at 6.5 Z TeV, after the present shutdown, are given.

TUPFI026	Investigations of the LHC Emittance Blow-Up during the 2012 Proton Run	emittance, injection, proton, target	1394
	M. Kuhn Uni HH, Hamburg, Germany G. Arduini, P. Baudrenghien, J. Emery, A. Guerrero, W. Höfle, V. Kain, M. Lamont, T. Mastoridis, F. Roncarolo, M. Sapinski, M. Schaumann, R.J. Steinhagen, G. Trad, D. Valuch CERN, Geneva, Switzerland
	About 30 % of the potential luminosity performance is lost through the different phases of the LHC cycle, mainly due to transverse emittance blow-up. Measuring the emittance growth is a difficult task with high intensity beams and changing energies. Improvements of the LHC transverse profile instrumentation helped to study various effects. A breakdown of the growth through the different phases of the LHC cycle is given as well as a comparison with the data from the LHC experiments for transverse beam size. In 2012 a number of possible sources and remedies have been studied. Among these are intra beam scattering, 50 Hz noise and the effect of the transverse damper gain. The results of the investigations are summarized in this paper. Requirements for transverse profile instrumentation for post LHC long shutdown operation to finally tackle the emittance growth are given as well.

TUPFI028	Beam Losses Through the LHC Operational Cycle in 2012	proton, beam-losses, emittance, injection	1400
	G. Papotti, A.A. Gorzawski, M. Hostettler, R. Schmidt CERN, Geneva, Switzerland
	We review the losses through the nominal LHC cycle for physics operation in 2012. The loss patterns are studied and categorized according to timescale, distribution, time in the cycle, which bunches are affected, whether coherent or incoherent. Possible causes and correlations are identified, e.g. to machine parameters or instability signatures. A comparison with losses in the previous years of operation is also shown.

TUPFI029	Luminosity Lifetime at the LHC in 2012 Proton Physics Operation	emittance, target, proton, optics	1403
	M. Hostettler, G. Papotti CERN, Geneva, Switzerland
	In 2012, the LHC was operated at 4 TeV flat top energy with beam parameters that allowed exceeding a peak instantaneous luminosity of 7500 (ub*s)^-1 and a total of 23 fb^-1 integrated luminosity in the ATLAS and CMS experiments. This paper elaborates on the evolution of the LHC luminosity and luminosity lifetime during proton physics fills and through the year 2012. Bunch to bunch differences and the impact of different machine settings are highlighted.

TUPFI030	LHC Machine Developments in 2011-12	optics, collimation, ion, octupole	1406
	G. Papotti, R.W. Aßmann, F. Zimmermann CERN, Geneva, Switzerland
	In 2011 and 2012 LHC machine development (MD) sessions were performed during dedicated slots of beam time. These MD studies were scheduled and planned well in advance. Study topics reflected the previously agreed priorities, such as further optimizing machine performance, exploring beam parameters beyond design targets, assessing machine limitations, testing new concepts and machine settings, preparing future LHC running in view of the 2013/14 LHC shutdown and the re-commissioning of the LHC at nominal beam energy in 2014/15. We describe the planning, preparation, execution, review, and documentation of these LHC beam studies and highlight some key results.

TUPFI031	Effect of Collision Pattern in the LHC on the Beam Stability: Requirements from Experiments and Operational Considerations	damping, injection, proton, collider	1409
	W. Herr, G. Arduini, R. Giachino, E. Métral, G. Papotti, T. Pieloni CERN, Geneva, Switzerland X. Buffat, N. Mounet EPFL, Lausanne, Switzerland S.M. White BNL, Upton, Long Island, New York, USA
	Coherent instabilities of bunches in the LHC bunch train can be observed when the tune spread from beam-beam interactions becomes insufficient to ensure Landau damping. In particular these effects are seen on bunches with a reduced number of beam-beam interactions due to their collision pattern. Furthermore, such a reduction of the necessary stability can occur during the processes when the beams are prepared for collisions or during the optimization procedure. We discuss the observations and possible countermeasures, in particular alternatives to the existing beam manipulation processes where such a situation can occur.

TUPFI032	Observation of Instabilities in the LHC due to Missing Head-on Beam-beam Interactions	damping, octupole, beam-beam-effects, betatron	1412
	W. Herr, G. Arduini, R. Giachino, E. Métral, G. Papotti, T. Pieloni CERN, Geneva, Switzerland X. Buffat, N. Mounet EPFL, Lausanne, Switzerland
	We report the observation of coherent instabilities on individual bunches out of the LHC bunch train. These instabilities occured spontaneously after several hours of stable beam while in other cases they were related to the application of a small transverse beam separation during a luminosity optimization. Only few bunches were affected, depending on there collision scheme and following various tests we interprete these instabilities as a sudden loss of Landau damping when the tune spread from the beam-beam interaction became insufficient.

TUPFI033	Colliding During the Squeeze and β* Leveling in the LHC	impedance, collider, controls, optics	1415
	X. Buffat EPFL, Lausanne, Switzerland W. Herr, M. Lamont, T. Pieloni, S. Redaelli, J. Wenninger CERN, Geneva, Switzerland
	While more challenging operationally, bringing the beams into collisions during the β squeeze rather than after presents some advantages. The large tune spread arising from the non-linearity of head-on beam-beam interactions can damp impedance-driven instabilities much more efficiently than external non-linearity such as octupoles presently used in operation. Moreover, colliding during the squeeze allows to level the luminosity, optimizing the pile-up in the experiments without changing the longitudinal distribution of collisions. Operational issues are discussed and experimental results from the LHC are presented.

TUPFI034	Observations of Two-beam Instabilities during the 2012 LHC Physics Run	octupole, damping, betatron, impedance	1418
	T. Pieloni EPFL, Lausanne, Switzerland G. Arduini, X. Buffat, R. Giachino, W. Herr, M. Lamont, N. Mounet, E. Métral, G. Papotti, B. Salvant, J. Wenninger CERN, Geneva, Switzerland S.M. White BNL, Upton, Long Island, New York, USA
	During the 2012 run coherent beam instabilities have been observed in the LHC at 4 TeV, during the betatron squeeze and in collision for special filling patterns. Several studies to characterize these instabilities have been carried out during operation and in special dedicated experiments. In this paper we summarize the observations collected for different machine parameters and the present understanding of the origin of these instabilities.

TUPFI035	Head-on and Long range Beam-beam Interactions in the LHC: Effective Tune Spread and Beam Stability due to Landau Damping	octupole, damping, lattice, feedback	1421
	X. Buffat EPFL, Lausanne, Switzerland W. Herr, N. Mounet, E. Métral, T. Pieloni CERN, Geneva, Switzerland
	We discuss the Landau damping of coherent instabilities in the presence of betatron tune spread. This tune spread can originate from dedicated non-linear magnets such as octupoles, or through the beam-beam interaction. In the latter case we have to distinguish the contribution from head-on and parasitic beam-beam interactions and the collision pattern of different bunches plays an important role. The interplay of these sources of tune spread and the resulting stability is discussed for the case of the LHC.

TUPFI037	Collimation Down to 2 Sigma in Special Physics Runs in the LHC	proton, scattering, background, emittance	1427
	H. Burkhardt, S. Jakobsen, S. Redaelli, B. Salvachua, G. Valentino CERN, Geneva, Switzerland
	We report on observations with collimation very close to the beam. Primary collimators were moved in small steps down to 2 σ from the beam axis to allow for measurements of very forward proton scattering in special high-beta runs in the LHC. We studied the reduction in intensity as a function of collimator position which provides information about the halo shape. After scraping at 2 σ, collimators were retracted to 2.5 σ. This allowed for measurements of very forward proton-proton scattering with roman pot detectors at 3 σ from the beam axis at acceptable background levels for about an hour. Good background conditions were restored by another scraping with primary collimators at 2 σ. Beam lifetimes and halo repopulation times were found to be sufficiently long to allow for several hours of data taking between scraping in a single LHC fill.

TUPFI038	Operation of the Betatron Squeeze at the LHC	optics, betatron, proton, injection	1430
	S. Redaelli, X. Buffat, M. Lamont, G.J. Müller, M. Solfaroli Camillocci, R. Tomás, J. Wenninger CERN, Geneva, Switzerland G.J. Müller TU Dresden, Dresden, Germany
	The betatron squeeze is one of the most delicate operational phases at the large Hadron collider as it entails changes of optics performed at top energy, with full intensities. Appropriate software was developed to handle the squeeze, which ensured an efficient commissioning down to a β^* of 60 cm and a smooth operation. Several optics configurations could be commissioned and put in operation for physics. The operational experience of the LHC runs from 2010 until 2012 is presented and the overall performance reviewed.

TUPFI042	Beam Parameters and Luminosity Time Evolution for an 80-km VHE-LHC	emittance, radiation, damping, collider	1442
	C.O. Domínguez, F. Zimmermann CERN, Geneva, Switzerland
	The Very High Energy LHC (VHE-LHC) is a recently proposed proton-proton collider in a new 80-km tunnel. With a dipole field of 15-20 T it would provide a collision energy of 76-100 TeV c.m. We discuss the VHE-LHC beam parameters and compute the time evolution of luminosity, beam current, emittances, bunch length, and beam-beam tune shift during a physics store. The results for VHE-LHC are compared with those for HE-LHC, a 33-TeV (20-T field) collider located in the existing LHC tunnel.

TUPFI044	LHC Optics with Crab-waist Collisions and Local Chromatic Correction	optics, sextupole, quadrupole, dipole	1448
	J.L. Abelleira, S. Russenschuck, F. Zimmermann CERN, Geneva, Switzerland C. Milardi, M. Zobov INFN/LNF, Frascati (Roma), Italy
	Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579. We report the status of the optics design for a local chromatic correction with extremely-flat beams at the LHC. Together with a Large Piwinski angle, this optics opens up the possibility of crab-waist collisions at the LHC, for which a new layout of the LHC insertion region (IR) is needed. We present a complete optics and discuss the parameters of the final "double-half" quadrupole.

TUPFI051	Optics Transition between Injection and Collision Optics for the HL-LHC Upgrade Project	quadrupole, optics, injection, insertion	1460
	M. Korostelev, A. Wolski The University of Liverpool, Liverpool, United Kingdom R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland M. Korostelev, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Plans for the luminosity upgrade of the LHC collider at CERN (HL-LHC) are based on implementation of magnets with larger apertures in the interaction regions, together with the ATS [] technique to reach very low values of the beta function at the collision points. The transition from injection to collision optics will be carried out in two stages, and will involve varying the strengths of the quadrupoles within the straight sections. Solutions for the optics transition have to meet a variety of challenging constraints, including constraints on the phase advances and Twiss parameters throughout the straights involved in the transition, specified minimum and maximum strengths of the quadrupoles, etc. Moreover, to minimize the time taken for the transition, the variation of the quadrupole strengths should be as smooth as possible, especially for the strongest quadrupoles. Avoiding changes of slope as much as possible will also minimize hysteresis effects in the super-conducting matching quadrupoles participating to the process. This paper presents one possible solution for the optics transition, calculated for the HLLHCv1.0 version of the optics and layout of the HL-LHC. S. Fartoukh, "An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade", in proceedings of IPAC11, p. 2088.

TUPFI056	A Muon Collider as a Higgs Factory	collider, emittance, factory, target	1472
	D.V. Neuffer, Y.I. Alexahin, M.A. Palmer Fermilab, Batavia, USA C.M. Ankenbrandt Muons. Inc., USA J.-P. Delahaye SLAC, Menlo Park, California, USA
	Because muons connect directly to a standard-model Higgs particle in s-channel production, a muon collider would be an ideal device for precision measurement of the mass and width of a Higgs-like particle, and for further exploration of its production and decay properties. The LHC has seen evidence for a 126 GeV Higgs particle, and a muon collider at that energy could be constructed. Parameters of a high-precision muon collider are presented and the necessary components and performance are described. An important advantage of the muon collider approach is that the spin precession of the muons will enable energy measurements at extremely high accuracy (E/E to 10^-6 or better). Extension to a higher-energy higher-luminosity device is also discussed.

TUPFI062	Operational Results of the LHC Luminosity Monitors until LS1	proton, monitoring, radiation, simulation	1490
	A. Ratti, S.C. Hedges, J. Jones, H.S. Matis, M. Placidi, W.C. Turner, V.K. Vytla LBNL, Berkeley, California, USA E. Bravin, F. Roncarolo CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	Funding: Work funded by the US Department of Energy through the US- LARP program. The monitors for the high luminosity regions in the LHC have been operating since 2009 to optimize the LHC's luminosity. The devices are gas ionization chambers inside the neutral particle absorber 140 m from the interaction point and monitor showers produced by high energy neutral particles from the collisions. They have the ability to resolve the bunch-by-bunch luminosity as well as to survive the extreme level of radiation in the nominal LHC operation. The devices have operated on a broad range of luminosity, from the initial 10²⁸ until the levels well beyond 10³³ reached in 2012. We present operational results of the device during proton and lead ion operations until LS1, which include runs at 40 MHz bunch rate and with p-Pb collisions.

TUPFI076	First RHIC Collider Test Operation at 2.5GeV Beam Energy	ion, multipole, dipole, injection	1523
	C. Montag, L. A. Ahrens, M. Bai, J. Beebe-Wang, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, C.J. Gardner, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, R.L. Hulsart, J.S. Laster, C. Liu, Y. Luo, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, J. Morris, S. Nemesure, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, J.E. Tuozzolo, M. Wilinski, A. Zaltsman, K. Zeno, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. To search for the critical point in the QCD phase diagram, RHIC needs to operate at a set of low gold beam energies between 2.5 and 20 GeV per nucleon. During run 12, first successful collider operation at the lowest energy of 2.5 GeV per nucleon was achieved. We present the challenges and achieved results, and discuss possible future upgrades and improvements.

TUPFI078	Measurement of the Total Cross Section of Uranium-uranium Collisions at a Center-of-mass Energy of 192.8 GeV per Nucleon-pair	ion, beam-losses, scattering, emittance	1529
	W. Fischer, A.J. Baltz, M. Blaskiewicz, K.A. Drees, D.M. Gassner, Y. Luo, M.G. Minty, P. Thieberger, M. Wilinski BNL, Upton, Long Island, New York, USA I.A. Pshenichnov RAS/INR, Moscow, Russia
	Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy. Heavy ion cross sections totaling several hundred barns have been calculated previously for the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). These total cross sections are more than an order of magnitude larger than the geometric ion-ion cross sections, primarily due to Bound-Free Pair Production (BFPP) and Electro-Magnetic Dissociation (EMD). Apart from a general interest in verifying the calculations experimentally, an accurate prediction of the losses created in the heavy ion collisions is of practical interest for the LHC, where some collision products are lost in cryogenically cooled magnets and have the potential to quench these magnets. In the 2012 RHIC run uranium ions collided with each other at a center-of-mass energy of 192.8 GeV per nucleon-pair with nearly all beam losses due to collisions. This allows for the measurement of the total cross section and a comparison with calculations.

TUPFI082	RHIC Performance for FY2012 Heavy Ion Run	ion, booster, feedback, heavy-ion	1538
	Y. Luo, J.G. Alessi, M. Bai, E.N. Beebe, J. Beebe-Wang, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, D.M. Gassner, X. Gu, Y. Hao, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, N.A. Kling, M. Lafky, J.S. Laster, C. Liu, D. Maffei, Y. Makdisi, M. Mapes, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, A.I. Pikin, P.H. Pile, V. Ptitsyn, D. Raparia, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, C. Schultheiss, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, J.E. Tuozzolo, B. Van Kuik, G. Wang, M. Wilinski, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the 2012 RHIC heavy ion run, we collided 96.4~GeV U-U ions and 100~GeV Cu-Au ions for the first time in RHIC. The new pre-injector with the electron-beam ion source (EBIS) was used to provide ions for RHIC ion collisions for the first time. By adding the horizontal cooling, the powerful 3-D stochastic cooling largely enhanced the luminosity. With the double bunch merging in the Booster and AGS, the bunch intensities of Cu and Au ions in RHIC surpassed their projections. Both PHENIX and STAR detectors reached their integrated luminosity goals for the U-U and Cu-Au collisions. In this article we review the machine improvement and performance in this run.

TUPME008	Beam Dynamics Studies for the Injection System of a High Luminosity Flavour Factory	linac, injection, electron, positron	1577
	D. Pellegrini CERN, Geneva, Switzerland M.E. Biagini, S. Guiducci INFN/LNF, Frascati (Roma), Italy
	The requirements, in terms of average luminosity and lifetimes, of high luminosity e⁺e⁻ colliders such as the Flavor factories, pose stringent constraints to the design of the injection complex. For the SuperB B-factory project at Tor Vergata, Italy, a design was developed to deliver full energy bunches (4.2 GeV e^- and 6.7 GeV e+) to the main rings every 30 ms aiming at a high and nearly constant luminosity. The system included a polarized electron gun, a positron production system, linac sections, a Damping Ring (DR) and transfer lines connecting to the collider Main Rings (MR). After the decision, due to budget issues, to rescale the project to a lower energy (2.3 GeV/beam) for a tau/charm flavour factory, the same design principles have been applied. In this paper beam dynamics studies from the DR to the MR entrance is presented, including optimization of the transfer lines and of the bunch compressor. A start to end simulation shows that the beam quality satisfies theinjection requirements, even in the presence of energy errors and collective effects like CSR and wakefields.

TUPME009	Measurement and Vibration Studies on the Final Focus Doublet at DAΦNE and new collider Implications	damping, collider, resonance, factory	1580
	S. Tomassini INFN/LNF, Frascati (Roma), Italy
	Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579. A Super Flavour Factory, to be built in the Tor Vergata University campus near Frascati, Italy, will have nano-beams in order to reach the design luminosity. The knowledge and compensation of the vibrations induced on the beams by the anthropic noise is then fundamental. The DAΦNE Phi-factory at LNF, Frascati, was upgraded in the second half of 2007 in order to implement the large Piwinski angle and crab waist collision scheme and in 2010 the KLOE experiment was rolled in for a new data taking and physic program. A measurement campaign has been performed on DAΦNE to find out the actual vibration sensitivity of the final focus doublets. Vibration measurements were performed on the Final Focus doublet because of luminosity losses and photon beam lines instability evidences. Results and stabilization technique to mitigate the effects of the ground motion induced by the “cultural noise” are presented. Implications on the design and stabilization of a Flavour Factory Final Focus doublets will be discussed.

TUPME011	Simulated Beam-beam Limit for Circular Higgs Factories	synchrotron, simulation, beam-beam-effects, radiation	1586
	K. Ohmi KEK, Ibaraki, Japan F. Zimmermann CERN, Geneva, Switzerland
	We report simulation studies of the beam-beam limit for two proposed circular e⁺e⁻ Higgs factories with circumference of 27 and 80 km, respectively, called LEP3 and TLEP. In particular we investigate the dependence of the steady-state luminosity and transverse beam sizes on the synchrotron tune (or momentum compaction factor) and on the betatron tunes, as well as the consequences of the strong radiation damping and the implications of the large hourglass effect.

TUPME016	Crosstalk Between Beam-beam Interaction and Lattice Nonlinearities in the SuperKEKB	simulation, lattice, resonance, betatron	1601
	D. Zhou, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto KEK, Ibaraki, Japan
	Momentum-dependent lattice nonlinearities have been proven to be important for the luminosity performance in the KEKB B-factory. As an upgrade of KEKB, the SuperKEKB adopts nano-beam scheme, in which the colliding beams are squeezed to extremely small sizes at the interaction point. Consequently, the lattice nonlinearities in SuperKEKB become more stronger than in KEKB. Using two codes, SAD and BBWS, we did various simulations to study the crosstalk between beam-beam interaction and lattice nonlinearities. It is found that lattice nonlinearities can cause remarkable luminosity loss in the SuperKEKB.

TUPME021	Optimization Parameter Design of a Circular e⁺e⁻ Higgs Factory	factory, emittance, synchrotron, collider	1616
	D. Wang, Y.W. An, J. Gao, H. Geng, Y.Y. Guo, Q. Qin, N. Wang, S. Wang, M. Xiao, G. Xu, S.Y. Xu IHEP, Beijing, People's Republic of China
	Funding: NSFC:11175192 In this paper we will show a genral method of how to make an optimized parameter design of a circular e⁺e⁻ Higgs Factory by using analytical expression of maximum beam-beam parameter and beamstrahlung beam lifetime started from given design goal and technical limitations. A parameter space has been explored.

TUPME024	Re-optimization of the Final Focus System Optics with Vertical Chromatic Correction	sextupole, linear-collider, collider, optics	1622
	Y. Wang, J. Gao IHEP, Beijing, People's Republic of China P. Bambade LAL, Orsay, France
	Funding: The France China Particle Physics Laboratory (FCPPL) and The National Natural Science Foundation of China (NSFC, Project 11175192) The purpose of the final focus (FF) system of the future linear collider (ILC and CLIC) is to demagnify the beam to the required size at the IP. This can be done in a compact way based on a local chromaticity correction. Two important issues are beam-beam induced radiation effects and the optical correction strategy to mitigate static and dynamic imperfections. For a small enough beam energy spread, we investigate the possibility to get a smaller vertical beam size, at the expense of a larger horizontal beam size, by re-optimising the final focus optics with chromatic correction mainly in the vertical plane. Firstly, we track the beam with MAD-X, with and without chromaticity correction, to estimate the optimum betax and betay values by rematching the linear optics, and cross-check and improve the rematching procedure with MAPCLASS. Then, we study the original design and an alternative simplified optical system, using a set of enlarged betax values, and optimize the sextupoles as a function of betay to minimize the vertical beam size for different assumptions on the energy spread.

TUPME031	Considerations for a Higgs Facility Based on Laser Wakefield Acceleration	plasma, laser, collider, electron	1643
	S. Hillenbrand, A.-S. Müller KIT, Karlsruhe, Germany R.W. Aßmann, S. Hillenbrand, D. Schulte CERN, Geneva, Switzerland
	Laser Wakefield Accelerators have seen tremendous progress over the last decades. It is hoped that they will allow to significantly reduce the size and cost of a future liner collider. Based on scaling laws, laser-driven plasma accelerators are investigated as drivers for smaller scale facilities capable of producing Z and Higgs bosons.

TUPME040	TLEP: High-performance Circular e⁺e⁻ Collider to Study the Higgs Boson	polarization, cryogenics, collider, wiggler	1658
	M. Koratzinos, O. Brunner, A.C. Butterworth, J.R. Ellis, P. Janot, E. Jensen, J.A. Osborne, F. Zimmermann CERN, Geneva, Switzerland R. Aleksan CEA/DSM/IRFU, France A.P. Blondel DPNC, Genève, Switzerland M. Zanetti MIT, Cambridge, Massachusetts, USA
	The recent discovery of a light Higgs boson has opened up considerable interest in circular e⁺e⁻ Higgs factories around the world. We report on the progress of the “TLEP3” concept since last year. Two options are considered: LEP3, a 240 GeV centre-of-mass (Ecm) e⁺e⁻ machine in the LHC tunnel with cost only a fraction of the cost of an equivalent linear collider, due to the use of existing infrastructure and the two general-purpose LHC detectors, and TLEP, an e⁺e⁻ machine in a new 80 km tunnel that can operate up to an Ecm of 350 GeV. Both concepts enjoy the extensive know-how on circular colliders and how to deliver their design luminosity, and the existence of up to four interaction points. The attainable luminosities are 10³⁴/cm²/s and 5x10³⁴/cm²/s per interaction point for LEP3 and TLEP respectively. Both machines can operate as Tera-Z and Mega-W boson factories, giving decisive opportunities for over-constraining the electroweak sector of the Standard Model. The technical challenges and possible ways to improve the performance further will be discussed.

TUPME049	Status of the Exploration of an Alternative CLIC First Energy Stage Based on Klystrons	klystron, linac, linear-collider, collider	1676
	D. Schulte, A. Grudiev, P. Lebrun, G. McMonagle, I. Syratchev, W. Wuensch CERN, Geneva, Switzerland
	The Compact Linear Collider is based on a two-beam scheme to accelerate the main, colliding beams. This scheme allows to reach very high centre-of-mass energies. At low collision energies the main beams could be accelerated by powering the accelerating structures with X-band instead of a second beam. We explore this option and indicate the parameters and conceptual design.

TUPME051	CLIC Final Focus System Alignment and Magnet Tolerances	quadrupole, sextupole, feedback, linear-collider	1682
	J. Snuverink, J. Barranco, H. Garcia, Y.I. Levinsen, D. Schulte, R. Tomás CERN, Geneva, Switzerland
	The design requirements for the magnets in the Compact Linear Collider (CLIC) Final Focus System (FFS) are very stringent. In this paper the sensitivity for the misalignment and the magnetic imperfections for the different magnets in the FFS and the crab cavity are presented. Possible mitigation methods are discussed.

TUPME054	Experimental Study of the Effect of Beam Loading on RF Breakdown Rate in CLIC High-gradient Accelerating Structures	linac, beam-loading, optics, beam-losses	1691
	F. Tecker, R. Corsini, M. Dayyani Kelisani, S. Döbert, A. Grudiev, O. Kononenko, S. Lebet, J.L. Navarro Quirante, G. Riddone, I. Syratchev, W. Wuensch CERN, Geneva, Switzerland A. Solodko JINR, Dubna, Moscow Region, Russia
	RF breakdown is a key issue for the multi-TeV high-luminosity e⁺e⁻ Compact Linear Collider (CLIC). Breakdowns in the high-gradient accelerator structures can deflect the beam and decrease the desired luminosity. The limitations of the accelerating structures due to breakdowns have been studied so far without a beam present in the structure. The presence of the beam modifies the distribution of the electrical and magnetic field distributions, which determine the breakdown rate. Therefore an experiment has been designed for high power testing a CLIC prototype accelerating structure with a beam present in the CLIC Test Facility (CTF3). A special beam line allows extracting a beam with nominal CLIC beam current and duration from the CTF3 linac. The paper describes the beam optics design for this experimental beam line and the commissioning of the experiment with beam.

TUPME059	Collisional Effects in Particle-in-Cell Beam-Beam Simulations	emittance, simulation, collider, proton	1700
	S. Paret, J. Qiang LBNL, Berkeley, California, USA
	Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231. Self-consistent particle tracking simulations (strong-strong) can be used to investigate the deterioration of colliding beams in a storage ring. However, the use of a small number of macroparticles copmared to the real number of particles magnifies the collisional effects and causes numerical noise. In particular, predictions of the emittance lifetime suffer from this numerical noise. In order to produce usable emittance predictions, the contribution of numerical noise to the simulated emittance growth has to be known. In this paper, we apply a diffusion model to strong-strong beam-beam simulations to study the numerical noise driven emittance growth. The scaling of emittance growth with numerical and physical parameters is discussed.

TUPME060	Tune Studies with Beam-Beam Effects in LHC	emittance, resonance, simulation, collider	1703
	S. Paret, J. Qiang LBNL, Berkeley, California, USA R. Alemany-Fernandez, X. Buffat, R. Calaga, K. Cornelis, M. Fitterer, R. Giachino, W. Herr, A. Macpherson, G. Papotti, T. Pieloni, S. Redaelli, F. Roncarolo, M. Schaumann, R. Suykerbuyk, G. Trad CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231. In high brightness colliders, the tune spread due to the collisions has a significant impact on the quality of the beams. The impact of the working point on emittance growth and beam lifetime has been observed in beam experiments in LHC. Strong-strong beam-beam simulations that were accomplished to better understand such observations are shown. Compared to experiments, wide ranged parameter scans can be done easily. Tune footprints and scans of the emittance growth obtained from simulations are discussed. Three cases are considered: Very high intensity, moderate intensity and collisions with separated beams.

TUPWA015	The Study of Bunch Lengthening in Electron Storage Ring	impedance, synchrotron, storage-ring, electron	1757
	Y. Li, L. Wang, Y. Zhang IHEP, Beijing, People's Republic of China
	The bunch length of electron storage ring of BEPCII was measured repeatedly during steady synchronous mode and streak camera was calibrated well. From the bench lengthening , the coupling impedance of the whole ring was estimated, which was according with theoretic impedance budget . Meanwhile, the small ap optics for improving the luminosity was feasible in collision mode form synchronous result .

TUPWA045	Longitudinal Space Charge Effects in the CLIC Drive Beam	space-charge, simulation, quadrupole, lattice	1811
	R.L. Lillestøl, S. Döbert, A. Latina, D. Schulte CERN, Geneva, Switzerland E. Adli, K.N. Sjobak University of Oslo, Oslo, Norway
	The CLIC main beam is accelerated by rf power generated from a high-intensity, low-energy electron drive beam. The accelerating fields are produced in Power Extraction and Transfer Structures, and are strongly dependent on the drive beam bunch distribution, as well as other parameters. We investigate how longitudinal space charge affects the bunch distribution and the corresponding power production, and discuss how the bunch length evolution can affect the main beam. We also describe the development of a Particle-in-Cell space charge solver which was used for the study.

WEPWO045	RF Multipolar Characterization of the Latest LHC Deflecting Cavities	cavity, multipole, dipole, extraction	2402
	M. Navarro-Tapia, R. Calaga, A. Grudiev CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Deflecting cavity geometries considered for the Large Hadron Collider (LHC)crab scheme lack axial symmetry resulting in non-zero higher-order components of the deflecting field. A formalism to express the higher-order multipoles was developed and applied on previous cavity designs to characterize their influence on the beam stability. In this paper, the radio frequency (RF) multipoles are numerically estimated for the latest cavity geometries and compared to the older versions. A sensitivity study is carried to understand the numerical error levels and define mechanical tolerances.

WEPWO050	Mechanical Study of 400 MHz Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade	cavity, simulation, vacuum, electron	2417
	B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu BNL, Upton, Long Island, New York, USA L. Alberty Vieira, R. Calaga CERN, Geneva, Switzerland T.L. Grimm Niowave, Inc., Lansing, Michigan, USA
	A prototype double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. A finite element model is used to simulate the mechanical properties of the crab cavity. The results are presented and a reinforcement concept is proposed to meet the safety requirements. The reinforcement components, as well as the cavity, are presently being fabricated at Niowave Inc.

WEPWO051	Manufacture of a Compact Prototype 4R Crab Cavity for HL-LHC	cavity, niobium, vacuum, electron	2420
	G. Burt, B.D.S. Hall, C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom L. Alberty Vieira, R. Calaga, O. Capatina CERN, Geneva, Switzerland C.H. Boulware, D. Gorelov, T.L. Grimm, C. Krizmanich, T.S. Lamie Niowave, Inc., Lansing, Michigan, USA C. Hill, P.A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.A. Rimmer, H. Wang JLAB, Newport News, Virginia, USA
	Funding: This work has been funded by the EU through EUCARD and HiLumi and by STFC via the Cockcroft Institute. A prototype compact SRF deflecting cavity has been manufactured for LHC. The base of the cavity has been machined out of large grain niobium ingot to allow the manufacture of the complex rod profile. Stiffening rods have been used to increase the mechanical strength of the outer can. Details of the cavity design and manufacture will be discussed.

WEPEA047	Dynamic Aperture Performance for Different Collision Optics Scenarios for the LHC Luminosity Upgrade	optics, multipole, dynamic-aperture, injection	2609
	M. Giovannozzi, R. De Maria, S.D. Fartoukh CERN, Geneva, Switzerland A. Chancé, B. Dalena, J. Payet CEA/IRFU, Gif-sur-Yvette, France K.M. Hock, M. Korostelev, A. Wolski The University of Liverpool, Liverpool, United Kingdom J. Resta-López IFIC, Valencia, Spain
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The ATS[1] optics solution for the HL-LHC offers the possibility of different collision optics, with a β^* as small as 10 cm in both transverse planes, or with a β^* aspect ratio of up to 4 pushing β^* to even smaller value (5cm) in the parallel separation plane while relaxing it (20 cm) in the crossing plane. The latter configuration features two possible options for alternated orientations of the crossing plane in the two high luminosity insertions, both considered in this study. In this paper we study the impact of few selected field imperfection models of the new magnets foreseen for the upgrade through tracking simulations and scaling laws. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA049	Analysis of the Non-linear Fringe Effects of Large Aperture Triplets for the HL LHC Project	quadrupole, dipole, simulation, optics	2615
	A.V. Bogomyagkov, E.B. Levichev, P.A. Piminov BINP SB RAS, Novosibirsk, Russia A. Chancé, B. Dalena, J. Payet CEA/IRFU, Gif-sur-Yvette, France R. De Maria, S.D. Fartoukh, M. Giovannozzi CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The HL-LHC project relies on large aperture quadrupoles which are compatible with the very large beam sizes in the inner triplets resulting from the strong reduction of β^*. As a result the beam is much more sensitive to non-linear perturbations in this region, such as those induced by the fringe fields of the low-beta quadrupoles. The spatial extension of these fringe fields increases as well more or less linearly with the coil aperture, which is an additional motivation to analyse this aspect in detail in the framework of the High Luminosity LHC design study. This paper will quantify this effect both by direct analytical estimates using first order Hamiltonian perturbation theory, and via numerical studies thanks to the dedicated implementation of a fringe field symplectic integrator in SixTrack.

WEPEA050	Analysis of Possible Functional Forms of the Scaling Law for Dynamic Aperture as a Function of Time	dynamic-aperture, beam-losses, simulation, lattice	2618
	M. Giovannozzi, R. De Maria, F. Lang CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. In recent studies, the evolution of the dynamic aperture with time has been fitted with a simple scaling law based on a limited number of free parameters. In this paper, different approaches to improve the numerical stability of the fit are presented, together with a new functional form. The results are discussed in details and applied to a set of numerical simulations for the LHC.

WEPEA058	LSS Layout Optimizations for Low-beta Optics for the HL-LHC	quadrupole, optics, sextupole, chromatic-effects	2639
	B.J. Holzer, R. De Maria CERN, Geneva, Switzerland R. Appleby, L.N.S. Thompson UMAN, Manchester, United Kingdom L.N.S. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 The High Luminosity LHC (HL-LHC) project aims to upgrade the existing LHC to a peak luminosity of the order 10³⁵cm^-2s⁻¹, while retaining as much of the nominal layout and hardware as possible. The current baseline for this upgrade is the use of the Achromatic Telescopic Squeeze (ATS) concept, which allows mini-Beta squeeze in IRs 1 and 5 (ATLAS and CMS respectively) far below that possible with nominal optics. However it is useful to both explore the parameter space of the ATS scheme while also attempting to push the boundaries of the nominal layout. This paper presents a study into maximising optical flexibility of the nominal LHC Long Straight Sections (LSSs) around IPs 1 and 5. This involves replacing, moving or adding magnets within the LSS to investigate feasibility of exploiting a more conventional optical scheme than the ATS scheme. In particular the option of replacing single LSS quadrupoles with doublets is explored. The study also looks at making similar changes to the LSS while also implementing the ATS scheme, to further explore the ATS parameter space with the benefit of experience gained into flexibility of a modified nominal LHC optical scheme.

WEPEA059	Study of the Impact of Fringe Fields of the Large Aperture Triplets on the Linear Optics of the HL-LHC	optics, quadrupole, collider, focusing	2642
	B.J. Holzer, R. De Maria, S. Russenschuck CERN, Geneva, Switzerland R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson UMAN, Manchester, United Kingdom L.N.S. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 High-luminosity hadron colliders such as the High Luminosity LHC (HL-LHC) project place demanding requirements on existing and new magnet technology. The very low β^* achieved by the Achromatic Telescopic Squeeze (ATS) optics scheme* for the HL-LHC in particular, requires large apertures in the high gradient Nb3Sn final focusing inner triplet triplet. Such magnets have extended fringe fields which perturb the linear and non-linear optics. This paper presents results of studies into the liner optics of the LHC using a range of fringe field models, including measurements of fringe fields from prototype magnets, and presents calculations of the beta-beating in the machine. Furthermore a similar study is presented on the nominal LHC optics, which uses final focus quadrupoles of higher gradient but significantly smaller aperture. * S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA060	Plans for the Upgrade of CERN's Heavy Ion Complex	ion, injection, linac, acceleration	2645
	D. Manglunki, M. E. Angoletta, H. Bartosik, A. Blas, D. Bodart, M.A. Bodendorfer, T. Bohl, J. Borburgh, E. Carlier, J.-M. Cravero, H. Damerau, L. Ducimetière, A. Findlay, R. Garoby, S.S. Gilardoni, B. Goddard, S. Hancock, E.B. Holzer, J.M. Jowett, T. Kramer, D. Kuchler, A.M. Lombardi, Y. Papaphilippou, S. Pasinelli, R. Scrivens, G. Tranquille CERN, Geneva, Switzerland
	To reach a luminosity higher than 6×10²⁷ Hz/cm² for Pb-Pb collisions, as expected by the ALICE experiment after its upgrade during the 2nd Long LHC Shutdown (LS2), several upgrades will have to be performed in the CERN accelerator complex, from the source to the LHC itself. This paper first details the present limitations and then describes the strategy for the different machines in the ion injector chain. Both filling schemes and possible hardware upgrades are discussed.

WEPEA061	The First LHC p-Pb run: Performance of the Heavy Ion Production Complex	ion, proton, heavy-ion, injection	2648
	D. Manglunki, M. E. Angoletta, H. Bartosik, G. Bellodi, A. Blas, M.A. Bodendorfer, T. Bohl, C. Carli, E. Carlier, S. Cettour Cave, K. Cornelis, H. Damerau, A. Findlay, S.S. Gilardoni, S. Hancock, J.M. Jowett, D. Kuchler, M. O'Neil, Y. Papaphilippou, S. Pasinelli, R. Scrivens, G. Tranquille, B. Vandorpe, U. Wehrle, J. Wenninger CERN, Geneva, Switzerland
	TThe first LHC proton-ion run took place in January-February 2013; it was the first extension to the collider programme, as this mode was not included in the design report. This paper presents the performance of the heavy ion and proton production complex, and details the issues encountered, in particular the creation of the same bunch pattern in both beams.

WEPEA064	SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers	coupling, simulation, injection, synchrotron	2657
	A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, O. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.

WEPEA067	Beam Optics Measurements through Turn by turn Beam Position Data in the SLS	betatron, storage-ring, optics, positron	2663
	P. Zisopoulos, Y. Papaphilippou CERN, Geneva, Switzerland A. Streun PSI, Villigen PSI, Switzerland V.G. Ziemann Uppsala University, Uppsala, Sweden
	Refined Fourier analysis of turn-by-turn (TBT) transverse position data measurements can be used for determining several beam properties of a ring, such as transverse tunes, optics functions, phases, chromatic properties and coupling. In particular, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm is used to analyze TBT data from the Swiss Light Source (SLS) storage ring in order to estimate on and off-momentum beam characteristics. Of particular interest is the potential of using the full position information within one turn in order to measure beam optics properties.

WEPEA071	Performance Limitations in the Lhc Due to Parasitic Beam-Beam Encounters - Parameter Dependence, Scaling, and Pacman Effects	dynamic-aperture, beam-beam-effects, emittance, target	2672
	T. Pieloni EPFL, Lausanne, Switzerland X. Buffat, R. Calaga, R. Calaga, R. Giachino, W. Herr, E. Métral, G. Papotti, G. Trad CERN, Geneva, Switzerland D. Kaltchev TRIUMF, Vancouver, Canada
	We studied possible limitations due to the long-range beam-beam effects in the LHC. With a large number of bunches and collisions in all interaction points, we have reduced the crossing angles (separation) to enhance long-range beam-beam effects to evaluate their influence on dynamic aperture and losses. Different β^*, number of bunches and intensities have been used in several dedicated experiments and allow the test of the expected scaling laws.

WEPEA076	Comparison of Taylor Maps with Radio Frequency Multipoles in a Thin Lens 6D Tracking Code	cavity, multipole, collider, hadron	2687
	D.R. Brett, R. Appleby UMAN, Manchester, United Kingdom J. Barranco, R. De Maria, R. Tomás CERN, Geneva, Switzerland
	Funding: HiLumi LHC Design Study is part of the High Luminosity LHC project and is part funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. SixTrack is a general purpose 6D thin lens tracking code used for dynamic aperture studies. In the high luminosity LHC upgrade it is proposed that crab cavities are used to enhance the luminosity. In this study, for the current proposed optics, we consider the use of RF multipoles and Taylor maps as methods to simulate crab cavity elements in the lattice.

WEPFI091	Design of a Normal-conducting RF-dipole Deflecting Cavity	cavity, dipole, simulation, extraction	2911
	T.H. Luo, D.J. Summers UMiss, University, Mississippi, USA D. Li LBNL, Berkeley, California, USA
	In this paper we present a novel design of a CW normal conducting RF deflecting cavity. The cavity is designed into a dipole-like structure, resulting a high (R/Q)_transverse. The geometry at high H field is optimized to lower the surface peak power. We will show the design of a 325 MHz and 163 MHz cavity based on this structure and compare their performances with their superconducting counterparts.

THPPA03	The Development of China’s Accelerators I Have Experienced	proton, synchrotron, linac, radiation	3144
	S.X. Fang IHEP, Beijing, People's Republic of China
	The development of China’s high energy accelerator for half a century falls into two stages, namely the first 20 hovering years (1958-1978) and the later 30 years of rapid development (from 1978 till now). I was lucky enough to have experienced the whole process, witnessed, and to some extent, joined in the decision-making, the projects approval, the designing, the development and construction of China's five large scientific facilities undertaken by the Institute of High Energy Physics in Beijing. A brief review is given of the previous stage of history regarding the consideration of China’s high energy accelerators in the first 20 years. A short presentation is also given of the later 30 years concerning the rapid development of the Beijing Electron-Positron Collider (BEPC and BEPCII), the completed BEPC-based Shanghai Synchrotron Radiation Facility (SSRF), the Chinese Spallation Neutron Source (CSNS) under construction, the high-intensity proton accelerator (ADS) used for nuclear waste transmutation and the proton therapy machine in the R&D stage.
	Slides THPPA03 [6.015 MB]

THPFI049	Evaluation of the NEG Coating Saturation Level after 3 Years of LHC Beam Operation	vacuum, proton, ion, electron	3397
	G. Bregliozzi, V. Baglin, J.M. Jimenez, G. Lanza, T. Porcelli CERN, Geneva, Switzerland
	The room temperature vacuum system of the Large Hadron Collider (LHC) at CERN system has been designed to ensure vacuum stability and beam lifetime of 100 h with nominal current of 0.56 A per beam at 7 TeV of energy. During last two years the LHC operated with proton beams at a maximum energy of 4 TeV, coasting for several hours each time, inducing high pressure due to different effects: synchrotron radiation, electron cloud and localized temperature increase. All these phenomena generated an important gas load from the vacuum chamber walls, which led in some cases to a partial or a total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG vacuum reactivation, it is necessary to take into account all these aspects and to regularly evaluate the saturation level of the NEG coating. This study analyses the saturation level of the NEG coated beam pipes in the LHC accelerator. Pressure reading variation without proton beams circulating are analysed and combined with laboratory studies of the NEG saturation behaviour and with Vacuum Stability Code (VASCO) simulations.

THPFI060	Development, Validation and Application of a Novel Method for Estimating the Thermal Conductance of Critical Interfaces in the Jaws of the LHC Collimation System	radiation, collimation, pick-up, target	3430
	I. Leitão CERN, Geneva, Switzerland
	The motivation for this project arises from the difficulty in quantifying the manufacturing quality of critical interfaces in the water cooled jaws of the TCTP and TCSP (Target Collimator Tertiary Pickup and Target Collimator Secondary Pickup) collimators. These interfaces play a decisive role in the transfer of heat deposited by the beam towards the cooling system avoiding excessive deformation of the collimator. Therefore, it was necessary to develop a non-destructive method that provides an estimation of the thermal conductance during the acceptance test of the TCTP and TCSP jaws. The method is based on experimental measurements of temperature evolution and numerical simulations. By matching experimental and numerical results it is possible to estimate the thermal conductance in several sections of the jaw. A simplified experimental installation was built to validate the method, then a fully automatic Test-Bench was developed and built for the future acceptance of the TCTP/TCSP jaws which will be manufactured and installed in the LHC. This novel method has shown its validity and has become a decisive tool for the development of the new generation of LHC collimators.

THPME044	Fabrication and Test of a 1 M Long Single-aperture 11 T Nb3Sn Dipole for LHC Upgrades	dipole, sextupole, interaction-region, magnet-design	3609
	A.V. Zlobin, N. Andreev, G. Apollinari, E.Z. Barzi, R. Bossert, G. Chlachidze, J. DiMarco, A. Nobrega, I. Novitski, D. Turrioni, G. Velev Fermilab, Batavia, USA B. Auchmann, M. Karppinen, L. Rossi, D. Smekens CERN, Geneva, Switzerland
	Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and European Commission under FP7 project HiLumi LHC, GA no.284404 The planned upgrade of the LHC collimation system includes two additional collimators to be installed in the dispersion suppressor areas around points 2, 3 and 7, and high luminosity interaction regions in points 1 and 5. The necessary longitudinal space for the collimators could be provided by replacing some 8.33 T NbTi LHC main dipoles with 11 T dipoles based on Nb3Sn superconductor and compatible with the LHC lattice and main systems. To demonstrate this possibility Fermilab and CERN have started in 2011 a joint R&D program with the goal of building by 2015 a 5.5-m long twin-aperture dipole prototype suitable for installation in the LHC. An important part of the program is the development and test a series of short single-aperture demonstration dipoles with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and ~20% margin. This paper describes the design features and test results of a 1-m long single-aperture Nb3Sn demonstrator dipole for the LHC collimation system upgrade.

THPWO077	Status and Plans for the Upgrade of the LHC Injectors	linac, injection, ion, extraction	3936
	R. Garoby, H. Damerau, S.S. Gilardoni, B. Goddard, K. Hanke, A.M. Lombardi, D. Manglunki, M. Meddahi, B. Mikulec, L. Ponce, E.N. Shaposhnikova, R. Steerenberg, M. Vretenar CERN, Geneva, Switzerland
	The plans for preparing the LHC injectors to fulfill the needs of the LHC during the next decade have significantly progressed in 2012. Linac4 construction has passed major steps of pre-series fabrication. Hardware developments and beam studies have allowed refining the baseline actions to implement and the beam characteristics achievable at injection into the collider for protons as well as for Lead ions. These achievements are described in this paper, together with the updated project planning matched to the new schedule of the LHC.

Paper

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MOYAB101

The First Years of LHC Operation for Luminosity Production

proton, injection, emittance, feedback

6

M. Lamont
CERN, Geneva, Switzerland

A summary of the first 3 years of LHC operation is presented with a discussion on the performance ramp-up, operation efficiencies and system reliability. The main contributory factors to peak and integrated luminosity performance are outlined.

Slides MOYAB101 [12.139 MB]

MOZB201

Overview of the LHeC Design Study at CERN

lepton, linac, proton, electron

40

O.S. Brüning
CERN, Geneva, Switzerland

The LHeC is a potential future lepton-hadron collider project at CERN based on the existing LHC infrastructure. The presentation highlights the main results of the recently published conceptual design report, including the findings of an international review committee that evaluated it. The presentation outlines the planed future studies and R&D activities for the next years.

Slides MOZB201 [11.894 MB]

MOZB202

The First Long Shutdown (LS1) for the LHC

dipole, ion, vacuum, radiation

44

F. Bordry, S. Baird, K. Foraz, A.-L. Perrot, R.I. Saban, J.Ph. G. L. Tock
CERN, Geneva, Switzerland

The LHC has been delivering data to the physics experiments since the first collisions in 2009. The first long shutdown (LS1), which started on 14 February 2013, was triggered by the need to consolidate the magnet interconnections so as to allow the LHC to operate at the design energy of 14 TeV in the centre-of-mass. It has now become a major shutdown which, in addition, includes other repairs, consolidation, upgrades and cabling across the whole accelerator complex and the associated experimental facilities. LS1 will see a massive programme of maintenance for the LHC and its injectors in the wake of more than three years of operation without the long winter shutdowns that were the norm in the past. The main driving effort will be the consolidation of the 10,170 high-current splices between the superconducting magnets. The presentation describes first the preparation phase with the prioritisation of the activities, the building of the teams and the detailed planning of the operation. Then, it gives the status after 3 months and the restart plans for all CERN accelerators. First lessons learnt for the 2nd long shutdown (LS2) will conclude the presentation.

Slides MOZB202 [13.675 MB]

MOODB201

Proton-nucleus Collisions in the LHC

injection, proton, heavy-ion, ion

49

J.M. Jowett, R. Alemany-Fernandez, P. Baudrenghien, D. Jacquet, M. Lamont, D. Manglunki, S. Redaelli, M. Sapinski, M. Schaumann, M. Solfaroli Camillocci, R. Tomás, J.A. Uythoven, D. Valuch, R. Versteegen, J. Wenninger
CERN, Geneva, Switzerland

Following the high integrated luminosity accumulated in the first two Pb-Pb collision runs in 2010 and 2011, the LHC heavy-ion physics community requested a first run with p-Pb collisions. This almost unprecedented mode of collider operation was not foreseen in the baseline design of the LHC whose two-in-one magnet design imposed equal rigidity and, hence, unequal revolution frequencies, during injection and ramp. Nevertheless, after a successful pilot physics fill in 2012, the LHC provided 31 nb^-1 of p-Pb luminosity per experiment, at an energy of 5.02 TeV per colliding nucleon pair, with several variations of the operating conditions, in early 2013. Together with a companion p-p run at 2.76 TeV, this was the last physics before the present long shutdown. We summarise the beam physics, operational adaptations and strategy that resulted in extremely rapid commissioning. Finally, we give an account of the progress of the run and provide an analysis of the performance.

Slides MOODB201 [6.547 MB]

MOPME004

Fast Luminosity Monitoring using Diamond Sensors for Super Flavour Factories

scattering, photon, electron, positron

473

C. Rimbault, P. Bambade
LAL, Orsay, France

Super flavour factories aim to reach very high luminosities thanks to a new concept whereby the ultra-low emittance beams collide with a large crossing angle. Fast luminosity measurements are needed as input to luminosity optimization and feedback in the presence of dynamic imperfections. The required small relative precision can be reached exploiting the very large cross section of the radiative Bhabha process at zero photon scattering angle. The instrumental technique selected to sustain the large particle fluxes is based on diamond sensors to be positioned via moveable stages immediately outside the beam pipe, at locations chosen to minimize the contamination from other particle loss mechanisms.

MOPME071

Characterisation of Si Detectors for use at 2 Kelvin

proton, cryogenics, radiation, superconducting-magnet

643

M.R. Bartosik, C. Arregui Rementeria, B. Dehning, T. Eisel, C. Kurfuerst, M. Sapinski
CERN, Geneva, Switzerland
V. Eremin, E. Verbitskaya
IOFFE, St. Petersburg, Russia

Funding: This research project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community’s Seventh Framework Programme under contract nr PITN-GA-2011-289485-OPAC.
It is expected that the luminosity of the Large Hadron Collider (LHC) will be bounded in the future by the beam loss limits of the superconducting magnets. To protect the superconducting magnets of the high luminosity insertions an optimal detection of the energy deposition by the shower of beam particles is necessary. Therefore beam Loss Monitors (BLM) need to be placed close to the particle impact location in the cold mass of the magnets where they should operate in superfluid helium at 1.9 Kelvin. To choose optimal detectors n-type silicon wafers have been examined at superfluid helium temperature whilst under irradiation from a high intensity proton beam. The radiation hardness and leakage current of these detectors were found to be significantly improved at 1.9 Kelvin when compared to their operation at room temperature.

MOPWO010

Machine Protection Studies for a Crab Cavity in the LHC

simulation, beam-losses, cavity, collimation

906

B. Yee-Rendon, R. Lopez-Fernandez
CINVESTAV, Mexico City, Mexico
T. Baer, J. Barranco, R. Calaga, A. Marsili, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland

Funding: US-LARP and CONACYT
Crab cavities (CCs) apply a transverse kick that rotate the bunches so as to have a head-on collision at the interaction point (IP). Such cavities were successfully used to improve the luminosity of KEKB. They are also a key ingredient of the HL-LHC project to increase the luminosity of the LHC. As CCs can rapidly change the particle trajectories, machine protection studies are required to assess the beam losses due to fast CC failures. In this paper, we discuss the effect of rapid voltage or phase changes in a CC for the HL-LHC layout using measured beam distributions from the present LHC.

MOPWO020

Space Charge Dominated Envelope Dynamics using GPUs

space-charge, simulation, controls, focusing

924

N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia

High power accelerator facilities lead to necessity to consider space charge forces. It is therefore important to study the space charge dynamics in the corresponding channels. To represent the space charge forces of the beam we have developed special software based on some analytical models for space charge distributions. Because calculations for space charge dynamics become extremely time consuming, we use a special algorithm for predictor-corrector method for evaluation scheme for beam map evaluation including the space charge forces. This method allows us to evaluate the map along the references trajectory and to create the beam envelope dynamics. The corresponding computer codes are realized using CUDA implementation of maps for particle dynamics. Some numerical results for different types of the beam channels are discussed. The survey of advantages and disadvantages of using different methods of parallelization and some parallel approaches will be done.

MOPWO032

SPS Scraping and LHC Transverse Tails

injection, emittance, beam-losses, controls

957

L.N. Drøsdal, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, O. Mete, B. Salvachua, G. Valentino, E. Veyrunes
CERN, Geneva, Switzerland

All high-intensity LHC beams have to be scraped before extraction from the SPS to remove the non-Gaussian transverse tails of the particle distributions. The tail particles would otherwise cause unacceptably high losses during injection or other phases of the LHC cycle. Studies have been carried out to quantify the scraping using injection losses and emittance measurements from wire scanners as diagnostics. Beams scraped in the SPS were scraped again in the LHC with collimators to investigate possible tail repopulation. The results of these studies will be presented in this paper.

MOPWO034

Energy Deposition Studies for the Upgrade of the LHC Injection Lines

injection, proton, optics, quadrupole

963

A. Mereghetti, O. Aberle, F. Cerutti, B. Goddard, V. Kain, F.L. Maciariello, M. Meddahi
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom
E. Gianfelice-Wendt
Fermilab, Batavia, USA

The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Given the challenging beam intensities and emittances, a review of the existing beam-intercepting devices is on-going, in order to assess heat loads and consequent thermo-mechanical stresses. Moreover, the exposure of downstream elements to induced shower radiation is assessed. The study is intended to spot possible issues and contribute to the definition of viable design and layout solutions.

MOPWO040

Analysis of Failures of the LHC Collimators during the 2010-2013 Operation

collimation, injection, controls, insertion

981

S. Redaelli, A. Masi
CERN, Geneva, Switzerland

The LHC collimation system must be available in all phases of the machine operation in order to handle the high stored beam energies. The system availability is therefore crucial to achieve an efficient LHC operation. The collimation system has proved to work reliably in the first years of LHC operation, with total stored energies up to 140 MJ. The impact on the machine availability has been limited. The analysis of collimation system availability and the failure rate in the years 2012-2012 is reviewed with the aim to identify possible further improvements for the future.

MOPWO041

Simulations and Measurements of Physics Debris Losses at the 4 TeV LHC

simulation, proton, background, dipole

984

A. Marsili, R. Bruce, F. Cerutti, S. Redaelli
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Simulations of energy deposition from the physics debris are normally done with shower simulation tools like FLUKA. Tracking tools like SixTrack allow faster simulations that open the possibility to study parametrically and optimize different layouts. In this paper, the results of FLUKA and SixTrack simulations are compared to beam measurements done for different collimator settings at 4 TeV, with p-p luminosities up to 7·10³³ cm^-2s⁻¹.

MOPWO042

Simulations of Collimation Cleaning Performance with HL-LHC Optics

optics, simulation, collimation, proton

987

A. Marsili, R. Bruce, R. De Maria, S.D. Fartoukh, S. Redaelli
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The upgrade of the LHC from the current set-up to high luminosity performances will provide new challenges for the protection of the machine. The different optics considered might create new needs for collimation, and require new collimation locations. In order to evaluate the cleaning performances of the collimation system, different halo cleaning simulations were performed with the particle tracking code SixTrack. This paper presents the cleaning performance simulation results for the high luminosity Achromatic Telescopic Squeeze optics considered as baseline for the HL-LHC. The new limitations observed and possible solutions are discussed.

MOPWO047

Studies of Thermal Loads on Collimators for HL-LHC Optics in case of Fast Losses

optics, proton, kicker, collimation

999

L. Lari, R. Bruce, F. Cerutti
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The new layouts for the HL-LHC pose new challenges in terms of proton loads on the collimators around the ring, in particular for the ones of in experimental regions that become critical with squeeze optics. New layouts are under consideration, which foresee updated collimation schemes. Simulations of halo loads for in case of fast failures have been setup with SixTrack in order to determine beam loss distributions for realistic error scenarios. The particle tracking studies might then be interfaced to tools like FLUKA to evaluate the thermal loads on collimators in case of failures. In this paper, the preliminary studies performed for the baseline HL-LHC optics layouts are presented.

MOPWO049

Lifetime Analysis at High Intensity Colliders Applied to the LHC

proton, collider, collimation, beam-losses

1005

B. Salvachua, R.W. Aßmann, R. Bruce, F. Burkart, S. Redaelli, G. Valentino, D. Wollmann
CERN, Geneva, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The beam lifetime is one of the main parameters to define the performance of a collider. In a super-conducting machine like the LHC, the lifetime determines the intensity reach for a given collimation cleaning. The beam lifetime can be calculated from the direct measurement of beam current. However, due to the noise in the beam current signal only an average lifetime over several seconds can be calculated. We propose here an alternative method, which uses the signal of the beam loss monitors in the vicinity of the primary collimators to get the instantaneous beam lifetime at the collimators. In this paper we compare the lifetime from the two methods and investigate the minimum lifetime over the LHC cycle for all the physics fills in 2011 and 2012. These data provide a reference for estimates of performance reach from collimator cleaning.

MOPWO051

Estimate of Warm Magnets Lifetime in the Betatron and Momentum Cleaning Insertions of the LHC

betatron, insertion, collimation, radiation

1011

B. Salvachua, R. Bruce, M. Brugger, F. Cerutti, S. Redaelli
CERN, Geneva, Switzerland

The CERN LHC collimation system is designed to perform momentum and betatron cleaning in different insertions, respectively IR3 and IR7. The insertions are not perfectly decoupled because the dispersion in IR7 is not null and the beta function in IR3 is not zero. The detailed sharing of losses between the two insertions depends on the relative collimator settings as observed by the change between 2011 and 2012 LHC operation. In this report, using the beam loss measurements at the primary collimators of IR3 and IR7, the total BLM losses in the two insertions are calculated and compared to each other. These studies are also used to quantify the total dose to warm magnets in those IRs with the aim to understand better their lifetime and the implications of the radiation to electronics. This will be of particular importance in view of LHC operating at nominal performance after several years of operation.

MOPWO054

The LHeC as a Higgs Boson Factory

linac, factory, lepton, electron

1017

F. Zimmermann, O.S. Brüning
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The LHeC is designed to collide a new 60 GeV energy electron beam, from a 3-pass ERL, with the 7 TeV energy LHC proton beam. At the present target ep luminosity of 10³³cm^-2s^-1, the LHeC would produce a few 1000 Higgs bosons per year, allowing for precision coupling measurements, especially of the H –> b bbar decay in charged current deep inelastic scattering (ep –> nu H X). With a significant increase of the luminosity, rarer channels become accessible, as the charm decay. Here such an increase, to the level of 10³⁴cm^-2s^-1 or even beyond, is considered from a combination of improvements, namely with a smaller proton beam emittance, with a further reduction of the proton IP beta function, an increase of the proton bunch intensity and with doubling the lepton beam current, compared to the canonical values assumed in the CDR.

MOPWO080

GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders

simulation, collider, electron, damping

1064

Y. Roblin, V.S. Morozov, B. Terzić
JLAB, Newport News, Virginia, USA
M. Aturban, D. Ranjan, M. Zubair
ODU CS, Norfolk, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.

TUYB101

Progress in Super B-Factories

emittance, linac, positron, alignment

1096

K. Akai
KEK, Ibaraki, Japan

The upgrade of B-Factories to Super B-Factories, which will search for new physics beyond the Standard Model, opens the way for new luminosity frontier. The status of Super B-Factories will be reported.

Slides TUYB101 [42.300 MB]

TUYB103

Status and Plans for the Polarized Hadron Collider at RHIC

polarization, proton, resonance, acceleration

1106

M. Bai, L. A. Ahrens, E.C. Aschenauer, G. Atoian, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, O. Eyser, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, A.I. Kirleis, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, V. Schoefer, F. Severino, T.C. Shrey, D. Smirnov, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
As the world’s only high energy polarized proton collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) has been providing collisions of polarized proton beams at beam energy from 100~GeV to 255~GeV for the past decade to explore the proton spin structure as well as other spin dependent measurements. With the help of two Siberian Snakes per accelerator plus outstanding beam control, beam polarization is preserved up to 100~GeV. About 10% polarization loss has been observed during the acceleration between 100~GeV and 255~GeV due to several strong depolarizing resonances. Moderate polarization loss was also observed during a typical 8 hour physics store. This presentation will overview the achieved performance of RHIC, both polarization as well as luminosity. The plan for providing high energy polarized He-3 collisions at RHIC will also be covered.
This work is on behalf of RHIC team.

Slides TUYB103 [12.854 MB]

TUPFI001

High Luminosity LHC Matching Section Layout vs Crab Cavity Voltage

optics, cavity, injection, quadrupole

1328

B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Chancé, J. Payet
CEA/DSM/IRFU, France
R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

Funding: The research leading to these results has received funding from the European Commission under the FP7 project HiLumi LHC, GA no. 284404, co-funded by the DoE, USA and KEK, Japan.
In the framework of the HL-LHC Upgrade project we present a new possible variant for the layout of the LHC matching section located in the high luminosity insertions. This layout is optimized to reduce the demand on the voltage of the crab cavities, while substantially improving the optics squeeze-ability, both in ATS [1] and non-ATS mode. These new layout will be described in details together with its performance figures in terms of mechanical acceptance, chromatic properties and optics flexibility. [1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI002

Electron Cloud and Scrubbing Studies for the LHC

injection, electron, emittance, dipole

1331

G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy
G. Arduini, V. Baglin, H. Bartosik, C.O. Domínguez, J. Esteban Müller, G. Iadarola, G. Rumolo, E.N. Shaposhnikova, L.J. Tavian, F. Zimmermann
CERN, Geneva, Switzerland
C.O. Domínguez
EPFL, Lausanne, Switzerland
G.H.I. Maury Cuna
CINVESTAV, Mexico City, Mexico

Electron cloud build-up resulting from beam-induced multipacting is one of the major limitations for the operation of the LHC with beams with close bunch spacing. Electron clouds induce unwanted pressure rise, heat loads on the beam screens of the superconducting magnets and beam instabilities. Operation with bunch spacing of 50 ns in 2011 and 2012 has required decreasing the Secondary Electron Yield of the beam screens below the multipacting threshold for beams with this bunch spacing. This was achieved by continuous electron bombardment induced by operating the machine with high intensity beams with 50 and 25 ns spacing during dedicated periods at injection energy (450 GeV) and at top energy (3.5 and 4 TeV). The evolution of the Secondary Electron Yield during these periods, at different sections of the machine, can be estimated by pressure, heat load and by bunch-by-bunch RF stable phase measurements. The experimental information on the scrubbing process will be discussed and a possible “scrubbing strategy” to allow the operation with 50ns and 25ns beams after the Long Shutdown in 2013-2014 will be presented.

TUPFI009

NICA project at JINR

ion, collider, booster, heavy-ion

1343

G.V. Trubnikov, N.N. Agapov, E.D. Donets, V.V. Fimushkin, E.V. Gorbachev, A. Govorov, E.V. Ivanov, V. Karpinsky, V.D. Kekelidze, H.G. Khodzhibagiyan, A.D. Kovalenko, K.A. Levterov, V.A. Matveev, I.N. Meshkov, V.A. Mikhailov, V. Monchinsky, S. Romanov, N. Shurkhno, A.O. Sidorin, V. Slepnev, A.V. Smirnov, A. Sorin, N.D. Topilin
JINR, Dubna, Moscow Region, Russia
O.I. Brovko, A.V. Butenko, E.E. Donets, A.V. Eliseev, O.S. Kozlov, A.V. Philippov, N.V. Semin, A. Tuzikov, V. Volkov
JINR/VBLHEP, Moscow, Russia

The Nuclotron-based Ion Collider fAcility (NICA) is a new accelerator complex being constructed at JINR aimed to provide the collider experiments with ion-ion (Au⁷⁹⁺) and ion-proton collisions at the energy range of 1-4.5 GeV/n and also the collisions of polarized proton-proton and deuteron-deuteron beams. Progress in the project realization is reported.

TUPFI010

The LHCb Online Luminosity Control and Monitoring

controls, target, dipole, proton

1346

R. Alemany-Fernandez, F. Follin, R. Jacobsson
CERN, Geneva, Switzerland

The online luminosity control consists of an automatic slow real-time feedback system controlled by specific LHCb software, which communicates directly with a LHC software application. The LHC application drives a set of corrector magnets to adjust the transversal beam overlap at the LHCb interaction point in order to keep the instantaneous luminosity aligned to the target luminosity provided by the experiment. It was proposed and tested first in July 2010, and it has been in routine operation during the first two years of physics luminosity data taking, 2011 and 2012. This paper describes the operational performance of the LHCb experiment and the LHC accelerator during the luminosity control of the experiment, the accounting of the recorded luminosity and dead time of the detector, and analyses the beam stability during the adjustment of the transverse beam overlap at the interaction point.

TUPFI011

Study and Operational Implementation of a Tilted Crossing Angle in LHCb

dipole, beam-losses, controls, monitoring

1349

R. Alemany-Fernandez, F. Follin, B.J. Holzer, D. Jacquet, R. Versteegen, J. Wenninger
CERN, Geneva, Switzerland

The current crossing angle scheme at LHCb interaction point (horizontal crossing angle and vertical beam separation) prohibits the use of the LHCb dipole positive polarity for 25 ns bunch spacing operation since the beam separation at the first parasitic encounter is very small inducing unwanted beam encounters. To overcome this limitation a different crossing angle scheme was proposed in 2007 by W. Herr and Y. Papaphilippou. The new schema implies a vertical external crossing angle that together with the horizontal internal crossing angle, from the LHCb dipole and its three compensator magnets, defines a new tilted crossing and separation plane providing enough beam separation at the parasitic encounters. This paper summarizes the feasibility study of the new crossing scheme, the implementation in routine operation and analyzes the beam stability during the building up of the tilted crossing plane.

TUPFI012

HL-LHC: Integrated Luminosity and Availability

target, simulation, collider, hadron

1352

A. Apollonio, M. Jonker, R. Schmidt, B. Todd, S. Wagner, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

The objective of LHC operation is to optimise the output for particle physics by maximising the integrated luminosity. An important constraint comes from the event pile–up for one bunch crossing that should not exceed 140 events per bunch crossing. With bunches every 25 ns the luminosity for data taking of the experiments should therefore not exceed 5*10³⁴ s⁻¹cm^-2. For the optimisation of the integrated luminosity it is planned to design HL-LHC for much higher luminosity than acceptable for the experiments and to limit the initial luminosity by operating with larger beam size at the collision points. During the fill, the beam size will be slowly reduced to keep the luminosity constant. The gain from luminosity levelling depends on the average length of the fills. Today, with the LHC operating at 4 TeV, most fills are terminated due to equipment failures, resulting in an average fill length of about 5 h. In this paper we discuss the expected integrated luminosity for HL-LHC as a function of fill length and time between fills, depending on the expected MTBF of the LHC systems with HL-LHC parameters. We derive an availability target for HL-LHC and discuss steps to achieve this.

TUPFI015

Study of the IR2 and IR8 Squeezeability for HL-LHC Upgrade

optics, injection, quadrupole, insertion

1361

A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia
R. De Maria
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The paper presents the results of the study of different optics configurations which allow to reach smaller beta functions at the IP2 and IP8 in the framework of the HL-LHC project. The variants at collision energies must be compatible with the ATS* scheme which provides small beta function at the IP1 and IP5 or provide low beta function for Alice and LHCb during ion operatations. The ones at injection must satisfy injection transfer lines and aperture constraints. The final goal is to find the overlap between the phase advances of all the configuration for IR2 and IR8 respectively, in order to mainting the LHC working point without rematching the remaining insertions.
* S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI016

Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy

target, quadrupole, lattice, dynamic-aperture

1364

Y. Nosochkov, Y. Cai, M.-H. Wang
SLAC, Menlo Park, California, USA
R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
For the high luminosity upgrade of the LHC (HL-LHC), the beta functions at two interaction points (IP) will be significantly reduced compared to the nominal LHC lattice. This will result in much higher peak beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme*. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The field error tolerances in these magnets must satisfy the required acceptable DA while being reasonably close to realistically achievable field quality. Evaluation of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gradient of 123 T/m and IP collision beta functions of 15 cm in both planes. Dynamic aperture calculations were performed using SixTrack. Details of the optimization of the IT field errors are presented along with corrections to achieve the field quality specifications.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI021

FLUKA Energy Deposition Studies for the HL-LHC

quadrupole, radiation, shielding, optics

1379

L.S. Esposito, F. Cerutti, E. Todesco
CERN, Geneva, Switzerland

The LHC upgrade, planned in about ten years from now, is envisaged to accumulate up to 3000 fb-1 integrated luminosity by running at a peak luminosity of 5 x 10³⁴ cm^-2 s⁻¹*. In order to reach such an ambitious goal, the high luminosity insertions need a major redesign implying a 150 mm aperture low-beta Inner Triplet, a superconducting D1 and new quadrupoles in the Matching Section. Energy deposition studies show that degradation of the coil insulator represents the most challenging issue from the radiation impact point of view. We propose a suitable shielding consisting of a beam screen with several mm tungsten absorbers at mid-planes to guarantee not to exceed a few ten MGys. This will also allow a good margin with respect to the risk of radiation induced quenches.
O. Brüning, L. Rossi, "High Luminosity Large Hadron Collider: A description for the European Strategy Preparatory Group," CERN ATS 2012-236.

TUPFI022

Power Load from Collision Debris on the LHC Point 8 Insertion Magnets Implied by the LHCb Luminosity Increase

dipole, quadrupole, proton, optics

1382

L.S. Esposito, F. Cerutti, A. Lechner, A. Mereghetti, A.A. Patapenka, V. Vlachoudis
CERN, Geneva, Switzerland
A. Mereghetti
UMAN, Manchester, United Kingdom
A.A. Patapenka
JIPNR-Sosny NASB, Minsk, Belarus

LHCb is aiming to upgrade its goal peak luminosity up to a value of 2 10³³ cm^-2 s⁻¹ after LS2. We investigate the collision debris impact on the machine elements by extensive FLUKA simulations, showing that the present machine layout is substantially compatible with such a luminosity goal. In particular the installation of a TAS (Target Absorber ofSecondaries, installed in front of the final focus Q1-Q3 quadrupole triplet in the LHC high luminosity insertions) turns out not to be necessary on the basis of the expected peak power deposition in the Q1 superconducting coils. A warm protection may be desirable to further reduce heat load and dose on the D2 recombination dipole, due to the absence of the TAN (Target Absorber of Neutrals, present in Point 1 and 5).

TUPFI023

Optics Design and Lattice Optimisation for the HL-LHC

optics, quadrupole, lattice, cavity

1385

B.J. Holzer, R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson
UMAN, Manchester, United Kingdom
A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia
A. Chancé
CEA, Gif-sur-Yvette, France
B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Faus-Golfe, J. Resta
IFIC, Valencia, Spain
K.M. Hock, M. Korostelev, L.N.S. Thompson, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C. Milardi
INFN/LNF, Frascati (Roma), Italy
J. Payet
CEA/DSM/IRFU, France
A. Wolski
The University of Liverpool, Liverpool, United Kingdom

Funding: The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Cap. Spec. Progr, Grant Agreement 284404.
The luminosity upgrade project of the LHC collider at CERN is based on a strong focusing scheme to reach smallest beam sizes at the collision points. Depending on the available magnet technology (Nb3Sn or NbTi) a number of beam optics has been developed to define the specifications for the new super conducting quadrupoles. In the context of the optics matching new issues have been addressed and new concepts have been used: Quadrupole strength flexibility and chromatic corrections have been studied, as well as the influence of quadrupole fringe fields. The lattice has been optimised including the needs of the foreseen crab cavities and the transition between injection and low β optics had to guarantee smooth gradient changes over a wide range of β* values. Tolerances on misalignments and power converter ripple have been re-evaluated. Finally the combination of the quadrupole strengths in the high luminosity matching sections with those in the neighboring sectors is explained, a key concept of the ATS to reach smallest β* values. This paper presents the results obtained within the HiLumi collaboration Task 2.2 and summarises the main parameters of the project.

TUPFI024

Influence of the Ats Optics on Intra-Beam Scattering for HL-LHC

optics, emittance, simulation, collider

1388

M. Schaumann, R. Bruce, J.M. Jowett
CERN, Geneva, Switzerland
M. Schaumann
RWTH, Aachen, Germany

In the future High Luminosity (HL-)LHC the influence of intra-beam scattering (IBS) will be stronger than in the present LHC, because of higher bunch intensity, small emittance and new optics. The new ATS-optics scheme modifies the lattice in the arcs around the main interaction points (IP) to provide β* values as small as 0.15m in the IP, however those modifications affect the IBS growth rates. In this paper proton IBS emittance growth rates are calculated with MADX and the Collider Time Evolution (CTE) program for two ATS-optics versions, different settings of the crossing angles and required corrections and various beam conditions at injection (450 GeV) and collision (7 TeV) energy. CTE simulations of the expected luminosity, intensity, emittance and bunch length evolution during fills are also presented

TUPFI025

Bunch-by-Bunch Analysis of the LHC Heavy-Ion Luminosity

injection, emittance, simulation, ion

1391

M. Schaumann, J.M. Jowett
CERN, Geneva, Switzerland

After the first run in 2010, the LHC continued its heavy-ion operation with collisions of lead nuclei in late 2011. The beam dynamics of those high intensity lead beams are strongly influenced by intra-beam scattering (IBS), especially on the injection plateau. Each batch injected from the SPS spends a different time at injection, introducing significant changes from batch to batch. Within the batches there is an even larger spread imprinted by the SPS injection plateau. This results in a spread of the luminosity produced in each bunch crossing. The particle losses during collisions are dominated by nuclear electromagnetic processes, leading to a non-exponential intensity decay during the fill and short luminosity lifetime at 3.5 Z TeV. The luminosity, emittance, intensity and bunch length evolution of the 2011 run was analysed bunch-by-bunch and compared with simulations. Based on this analysis, estimates of the potential luminosity performance at 6.5 Z TeV, after the present shutdown, are given.

TUPFI026

Investigations of the LHC Emittance Blow-Up during the 2012 Proton Run

emittance, injection, proton, target

1394

M. Kuhn
Uni HH, Hamburg, Germany
G. Arduini, P. Baudrenghien, J. Emery, A. Guerrero, W. Höfle, V. Kain, M. Lamont, T. Mastoridis, F. Roncarolo, M. Sapinski, M. Schaumann, R.J. Steinhagen, G. Trad, D. Valuch
CERN, Geneva, Switzerland

About 30 % of the potential luminosity performance is lost through the different phases of the LHC cycle, mainly due to transverse emittance blow-up. Measuring the emittance growth is a difficult task with high intensity beams and changing energies. Improvements of the LHC transverse profile instrumentation helped to study various effects. A breakdown of the growth through the different phases of the LHC cycle is given as well as a comparison with the data from the LHC experiments for transverse beam size. In 2012 a number of possible sources and remedies have been studied. Among these are intra beam scattering, 50 Hz noise and the effect of the transverse damper gain. The results of the investigations are summarized in this paper. Requirements for transverse profile instrumentation for post LHC long shutdown operation to finally tackle the emittance growth are given as well.

TUPFI028

Beam Losses Through the LHC Operational Cycle in 2012

proton, beam-losses, emittance, injection

1400

G. Papotti, A.A. Gorzawski, M. Hostettler, R. Schmidt
CERN, Geneva, Switzerland

We review the losses through the nominal LHC cycle for physics operation in 2012. The loss patterns are studied and categorized according to timescale, distribution, time in the cycle, which bunches are affected, whether coherent or incoherent. Possible causes and correlations are identified, e.g. to machine parameters or instability signatures. A comparison with losses in the previous years of operation is also shown.

TUPFI029

Luminosity Lifetime at the LHC in 2012 Proton Physics Operation

emittance, target, proton, optics

1403

M. Hostettler, G. Papotti
CERN, Geneva, Switzerland

In 2012, the LHC was operated at 4 TeV flat top energy with beam parameters that allowed exceeding a peak instantaneous luminosity of 7500 (ub*s)^-1 and a total of 23 fb^-1 integrated luminosity in the ATLAS and CMS experiments. This paper elaborates on the evolution of the LHC luminosity and luminosity lifetime during proton physics fills and through the year 2012. Bunch to bunch differences and the impact of different machine settings are highlighted.

TUPFI030

LHC Machine Developments in 2011-12

optics, collimation, ion, octupole

1406

G. Papotti, R.W. Aßmann, F. Zimmermann
CERN, Geneva, Switzerland

In 2011 and 2012 LHC machine development (MD) sessions were performed during dedicated slots of beam time. These MD studies were scheduled and planned well in advance. Study topics reflected the previously agreed priorities, such as further optimizing machine performance, exploring beam parameters beyond design targets, assessing machine limitations, testing new concepts and machine settings, preparing future LHC running in view of the 2013/14 LHC shutdown and the re-commissioning of the LHC at nominal beam energy in 2014/15. We describe the planning, preparation, execution, review, and documentation of these LHC beam studies and highlight some key results.

TUPFI031

Effect of Collision Pattern in the LHC on the Beam Stability: Requirements from Experiments and Operational Considerations

damping, injection, proton, collider

1409

W. Herr, G. Arduini, R. Giachino, E. Métral, G. Papotti, T. Pieloni
CERN, Geneva, Switzerland
X. Buffat, N. Mounet
EPFL, Lausanne, Switzerland
S.M. White
BNL, Upton, Long Island, New York, USA

Coherent instabilities of bunches in the LHC bunch train can be observed when the tune spread from beam-beam interactions becomes insufficient to ensure Landau damping. In particular these effects are seen on bunches with a reduced number of beam-beam interactions due to their collision pattern. Furthermore, such a reduction of the necessary stability can occur during the processes when the beams are prepared for collisions or during the optimization procedure. We discuss the observations and possible countermeasures, in particular alternatives to the existing beam manipulation processes where such a situation can occur.

TUPFI032

Observation of Instabilities in the LHC due to Missing Head-on Beam-beam Interactions

damping, octupole, beam-beam-effects, betatron

1412

W. Herr, G. Arduini, R. Giachino, E. Métral, G. Papotti, T. Pieloni
CERN, Geneva, Switzerland
X. Buffat, N. Mounet
EPFL, Lausanne, Switzerland

We report the observation of coherent instabilities on individual bunches out of the LHC bunch train. These instabilities occured spontaneously after several hours of stable beam while in other cases they were related to the application of a small transverse beam separation during a luminosity optimization. Only few bunches were affected, depending on there collision scheme and following various tests we interprete these instabilities as a sudden loss of Landau damping when the tune spread from the beam-beam interaction became insufficient.

TUPFI033

Colliding During the Squeeze and β* Leveling in the LHC

impedance, collider, controls, optics

1415

X. Buffat
EPFL, Lausanne, Switzerland
W. Herr, M. Lamont, T. Pieloni, S. Redaelli, J. Wenninger
CERN, Geneva, Switzerland

While more challenging operationally, bringing the beams into collisions during the β squeeze rather than after presents some advantages. The large tune spread arising from the non-linearity of head-on beam-beam interactions can damp impedance-driven instabilities much more efficiently than external non-linearity such as octupoles presently used in operation. Moreover, colliding during the squeeze allows to level the luminosity, optimizing the pile-up in the experiments without changing the longitudinal distribution of collisions. Operational issues are discussed and experimental results from the LHC are presented.

TUPFI034

Observations of Two-beam Instabilities during the 2012 LHC Physics Run

octupole, damping, betatron, impedance

1418

T. Pieloni
EPFL, Lausanne, Switzerland
G. Arduini, X. Buffat, R. Giachino, W. Herr, M. Lamont, N. Mounet, E. Métral, G. Papotti, B. Salvant, J. Wenninger
CERN, Geneva, Switzerland
S.M. White
BNL, Upton, Long Island, New York, USA

During the 2012 run coherent beam instabilities have been observed in the LHC at 4 TeV, during the betatron squeeze and in collision for special filling patterns. Several studies to characterize these instabilities have been carried out during operation and in special dedicated experiments. In this paper we summarize the observations collected for different machine parameters and the present understanding of the origin of these instabilities.

TUPFI035

Head-on and Long range Beam-beam Interactions in the LHC: Effective Tune Spread and Beam Stability due to Landau Damping

octupole, damping, lattice, feedback

1421

X. Buffat
EPFL, Lausanne, Switzerland
W. Herr, N. Mounet, E. Métral, T. Pieloni
CERN, Geneva, Switzerland

We discuss the Landau damping of coherent instabilities in the presence of betatron tune spread. This tune spread can originate from dedicated non-linear magnets such as octupoles, or through the beam-beam interaction. In the latter case we have to distinguish the contribution from head-on and parasitic beam-beam interactions and the collision pattern of different bunches plays an important role. The interplay of these sources of tune spread and the resulting stability is discussed for the case of the LHC.

TUPFI037

Collimation Down to 2 Sigma in Special Physics Runs in the LHC

proton, scattering, background, emittance

1427

H. Burkhardt, S. Jakobsen, S. Redaelli, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland

We report on observations with collimation very close to the beam. Primary collimators were moved in small steps down to 2 σ from the beam axis to allow for measurements of very forward proton scattering in special high-beta runs in the LHC. We studied the reduction in intensity as a function of collimator position which provides information about the halo shape. After scraping at 2 σ, collimators were retracted to 2.5 σ. This allowed for measurements of very forward proton-proton scattering with roman pot detectors at 3 σ from the beam axis at acceptable background levels for about an hour. Good background conditions were restored by another scraping with primary collimators at 2 σ. Beam lifetimes and halo repopulation times were found to be sufficiently long to allow for several hours of data taking between scraping in a single LHC fill.

TUPFI038

Operation of the Betatron Squeeze at the LHC

optics, betatron, proton, injection

1430

S. Redaelli, X. Buffat, M. Lamont, G.J. Müller, M. Solfaroli Camillocci, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland
G.J. Müller
TU Dresden, Dresden, Germany

The betatron squeeze is one of the most delicate operational phases at the large Hadron collider as it entails changes of optics performed at top energy, with full intensities. Appropriate software was developed to handle the squeeze, which ensured an efficient commissioning down to a β^* of 60 cm and a smooth operation. Several optics configurations could be commissioned and put in operation for physics. The operational experience of the LHC runs from 2010 until 2012 is presented and the overall performance reviewed.

TUPFI042

Beam Parameters and Luminosity Time Evolution for an 80-km VHE-LHC

emittance, radiation, damping, collider

1442

C.O. Domínguez, F. Zimmermann
CERN, Geneva, Switzerland

The Very High Energy LHC (VHE-LHC) is a recently proposed proton-proton collider in a new 80-km tunnel. With a dipole field of 15-20 T it would provide a collision energy of 76-100 TeV c.m. We discuss the VHE-LHC beam parameters and compute the time evolution of luminosity, beam current, emittances, bunch length, and beam-beam tune shift during a physics store. The results for VHE-LHC are compared with those for HE-LHC, a 33-TeV (20-T field) collider located in the existing LHC tunnel.

TUPFI044

LHC Optics with Crab-waist Collisions and Local Chromatic Correction

optics, sextupole, quadrupole, dipole

1448

J.L. Abelleira, S. Russenschuck, F. Zimmermann
CERN, Geneva, Switzerland
C. Milardi, M. Zobov
INFN/LNF, Frascati (Roma), Italy

Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579.
We report the status of the optics design for a local chromatic correction with extremely-flat beams at the LHC. Together with a Large Piwinski angle, this optics opens up the possibility of crab-waist collisions at the LHC, for which a new layout of the LHC insertion region (IR) is needed. We present a complete optics and discuss the parameters of the final "double-half" quadrupole.

TUPFI051

Optics Transition between Injection and Collision Optics for the HL-LHC Upgrade Project

quadrupole, optics, injection, insertion

1460

M. Korostelev, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
M. Korostelev, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Plans for the luminosity upgrade of the LHC collider at CERN (HL-LHC) are based on implementation of magnets with larger apertures in the interaction regions, together with the ATS [*] technique to reach very low values of the beta function at the collision points. The transition from injection to collision optics will be carried out in two stages, and will involve varying the strengths of the quadrupoles within the straight sections. Solutions for the optics transition have to meet a variety of challenging constraints, including constraints on the phase advances and Twiss parameters throughout the straights involved in the transition, specified minimum and maximum strengths of the quadrupoles, etc. Moreover, to minimize the time taken for the transition, the variation of the quadrupole strengths should be as smooth as possible, especially for the strongest quadrupoles. Avoiding changes of slope as much as possible will also minimize hysteresis effects in the super-conducting matching quadrupoles participating to the process. This paper presents one possible solution for the optics transition, calculated for the HLLHCv1.0 version of the optics and layout of the HL-LHC.
* S. Fartoukh, "An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade", in proceedings of IPAC11, p. 2088.

TUPFI056

A Muon Collider as a Higgs Factory

collider, emittance, factory, target

1472

D.V. Neuffer, Y.I. Alexahin, M.A. Palmer
Fermilab, Batavia, USA
C.M. Ankenbrandt
Muons. Inc., USA
J.-P. Delahaye
SLAC, Menlo Park, California, USA

Because muons connect directly to a standard-model Higgs particle in s-channel production, a muon collider would be an ideal device for precision measurement of the mass and width of a Higgs-like particle, and for further exploration of its production and decay properties. The LHC has seen evidence for a 126 GeV Higgs particle, and a muon collider at that energy could be constructed. Parameters of a high-precision muon collider are presented and the necessary components and performance are described. An important advantage of the muon collider approach is that the spin precession of the muons will enable energy measurements at extremely high accuracy (E/E to 10^-6 or better). Extension to a higher-energy higher-luminosity device is also discussed.

TUPFI062

Operational Results of the LHC Luminosity Monitors until LS1

proton, monitoring, radiation, simulation

1490

A. Ratti, S.C. Hedges, J. Jones, H.S. Matis, M. Placidi, W.C. Turner, V.K. Vytla
LBNL, Berkeley, California, USA
E. Bravin, F. Roncarolo
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: Work funded by the US Department of Energy through the US- LARP program.
The monitors for the high luminosity regions in the LHC have been operating since 2009 to optimize the LHC's luminosity. The devices are gas ionization chambers inside the neutral particle absorber 140 m from the interaction point and monitor showers produced by high energy neutral particles from the collisions. They have the ability to resolve the bunch-by-bunch luminosity as well as to survive the extreme level of radiation in the nominal LHC operation. The devices have operated on a broad range of luminosity, from the initial 10²⁸ until the levels well beyond 10³³ reached in 2012. We present operational results of the device during proton and lead ion operations until LS1, which include runs at 40 MHz bunch rate and with p-Pb collisions.

TUPFI076

First RHIC Collider Test Operation at 2.5GeV Beam Energy

ion, multipole, dipole, injection

1523

C. Montag, L. A. Ahrens, M. Bai, J. Beebe-Wang, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, W. Fischer, C.J. Gardner, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, R.L. Hulsart, J.S. Laster, C. Liu, Y. Luo, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, J. Morris, S. Nemesure, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, V. Schoefer, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, J.E. Tuozzolo, M. Wilinski, A. Zaltsman, K. Zeno, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
To search for the critical point in the QCD phase diagram, RHIC needs to operate at a set of low gold beam energies between 2.5 and 20 GeV per nucleon. During run 12, first successful collider operation at the lowest energy of 2.5 GeV per nucleon was achieved. We present the challenges and achieved results, and discuss possible future upgrades and improvements.

TUPFI078

Measurement of the Total Cross Section of Uranium-uranium Collisions at a Center-of-mass Energy of 192.8 GeV per Nucleon-pair

ion, beam-losses, scattering, emittance

1529

W. Fischer, A.J. Baltz, M. Blaskiewicz, K.A. Drees, D.M. Gassner, Y. Luo, M.G. Minty, P. Thieberger, M. Wilinski
BNL, Upton, Long Island, New York, USA
I.A. Pshenichnov
RAS/INR, Moscow, Russia

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
Heavy ion cross sections totaling several hundred barns have been calculated previously for the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). These total cross sections are more than an order of magnitude larger than the geometric ion-ion cross sections, primarily due to Bound-Free Pair Production (BFPP) and Electro-Magnetic Dissociation (EMD). Apart from a general interest in verifying the calculations experimentally, an accurate prediction of the losses created in the heavy ion collisions is of practical interest for the LHC, where some collision products are lost in cryogenically cooled magnets and have the potential to quench these magnets. In the 2012 RHIC run uranium ions collided with each other at a center-of-mass energy of 192.8 GeV per nucleon-pair with nearly all beam losses due to collisions. This allows for the measurement of the total cross section and a comparison with calculations.

TUPFI082

RHIC Performance for FY2012 Heavy Ion Run

ion, booster, feedback, heavy-ion

1538

Y. Luo, J.G. Alessi, M. Bai, E.N. Beebe, J. Beebe-Wang, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, D.M. Gassner, X. Gu, Y. Hao, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, N.A. Kling, M. Lafky, J.S. Laster, C. Liu, D. Maffei, Y. Makdisi, M. Mapes, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, A.I. Pikin, P.H. Pile, V. Ptitsyn, D. Raparia, G. Robert-Demolaize, T. Roser, P. Sampson, J. Sandberg, V. Schoefer, C. Schultheiss, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, J.E. Tuozzolo, B. Van Kuik, G. Wang, M. Wilinski, A. Zaltsman, K. Zeno, S.Y. Zhang, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the 2012 RHIC heavy ion run, we collided 96.4~GeV U-U ions and 100~GeV Cu-Au ions for the first time in RHIC. The new pre-injector with the electron-beam ion source (EBIS) was used to provide ions for RHIC ion collisions for the first time. By adding the horizontal cooling, the powerful 3-D stochastic cooling largely enhanced the luminosity. With the double bunch merging in the Booster and AGS, the bunch intensities of Cu and Au ions in RHIC surpassed their projections. Both PHENIX and STAR detectors reached their integrated luminosity goals for the U-U and Cu-Au collisions. In this article we review the machine improvement and performance in this run.

TUPME008

Beam Dynamics Studies for the Injection System of a High Luminosity Flavour Factory

linac, injection, electron, positron

1577

D. Pellegrini
CERN, Geneva, Switzerland
M.E. Biagini, S. Guiducci
INFN/LNF, Frascati (Roma), Italy

The requirements, in terms of average luminosity and lifetimes, of high luminosity e⁺e⁻ colliders such as the Flavor factories, pose stringent constraints to the design of the injection complex. For the SuperB B-factory project at Tor Vergata, Italy, a design was developed to deliver full energy bunches (4.2 GeV e^- and 6.7 GeV e+) to the main rings every 30 ms aiming at a high and nearly constant luminosity. The system included a polarized electron gun, a positron production system, linac sections, a Damping Ring (DR) and transfer lines connecting to the collider Main Rings (MR). After the decision, due to budget issues, to rescale the project to a lower energy (2.3 GeV/beam) for a tau/charm flavour factory, the same design principles have been applied. In this paper beam dynamics studies from the DR to the MR entrance is presented, including optimization of the transfer lines and of the bunch compressor. A start to end simulation shows that the beam quality satisfies theinjection requirements, even in the presence of energy errors and collective effects like CSR and wakefields.

TUPME009

Measurement and Vibration Studies on the Final Focus Doublet at DAΦNE and new collider Implications

damping, collider, resonance, factory

1580

S. Tomassini
INFN/LNF, Frascati (Roma), Italy

Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579.
A Super Flavour Factory, to be built in the Tor Vergata University campus near Frascati, Italy, will have nano-beams in order to reach the design luminosity. The knowledge and compensation of the vibrations induced on the beams by the anthropic noise is then fundamental. The DAΦNE Phi-factory at LNF, Frascati, was upgraded in the second half of 2007 in order to implement the large Piwinski angle and crab waist collision scheme and in 2010 the KLOE experiment was rolled in for a new data taking and physic program. A measurement campaign has been performed on DAΦNE to find out the actual vibration sensitivity of the final focus doublets. Vibration measurements were performed on the Final Focus doublet because of luminosity losses and photon beam lines instability evidences. Results and stabilization technique to mitigate the effects of the ground motion induced by the “cultural noise” are presented. Implications on the design and stabilization of a Flavour Factory Final Focus doublets will be discussed.

TUPME011

Simulated Beam-beam Limit for Circular Higgs Factories

synchrotron, simulation, beam-beam-effects, radiation

1586

K. Ohmi
KEK, Ibaraki, Japan
F. Zimmermann
CERN, Geneva, Switzerland

We report simulation studies of the beam-beam limit for two proposed circular e⁺e⁻ Higgs factories with circumference of 27 and 80 km, respectively, called LEP3 and TLEP. In particular we investigate the dependence of the steady-state luminosity and transverse beam sizes on the synchrotron tune (or momentum compaction factor) and on the betatron tunes, as well as the consequences of the strong radiation damping and the implications of the large hourglass effect.

TUPME016

Crosstalk Between Beam-beam Interaction and Lattice Nonlinearities in the SuperKEKB

simulation, lattice, resonance, betatron

1601

D. Zhou, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto
KEK, Ibaraki, Japan

Momentum-dependent lattice nonlinearities have been proven to be important for the luminosity performance in the KEKB B-factory. As an upgrade of KEKB, the SuperKEKB adopts nano-beam scheme, in which the colliding beams are squeezed to extremely small sizes at the interaction point. Consequently, the lattice nonlinearities in SuperKEKB become more stronger than in KEKB. Using two codes, SAD and BBWS, we did various simulations to study the crosstalk between beam-beam interaction and lattice nonlinearities. It is found that lattice nonlinearities can cause remarkable luminosity loss in the SuperKEKB.

TUPME021

Optimization Parameter Design of a Circular e⁺e⁻ Higgs Factory

factory, emittance, synchrotron, collider

1616

D. Wang, Y.W. An, J. Gao, H. Geng, Y.Y. Guo, Q. Qin, N. Wang, S. Wang, M. Xiao, G. Xu, S.Y. Xu
IHEP, Beijing, People's Republic of China

Funding: NSFC:11175192
In this paper we will show a genral method of how to make an optimized parameter design of a circular e⁺e⁻ Higgs Factory by using analytical expression of maximum beam-beam parameter and beamstrahlung beam lifetime started from given design goal and technical limitations. A parameter space has been explored.

TUPME024

Re-optimization of the Final Focus System Optics with Vertical Chromatic Correction

sextupole, linear-collider, collider, optics

1622

Y. Wang, J. Gao
IHEP, Beijing, People's Republic of China
P. Bambade
LAL, Orsay, France

Funding: The France China Particle Physics Laboratory (FCPPL) and The National Natural Science Foundation of China (NSFC, Project 11175192)
The purpose of the final focus (FF) system of the future linear collider (ILC and CLIC) is to demagnify the beam to the required size at the IP. This can be done in a compact way based on a local chromaticity correction. Two important issues are beam-beam induced radiation effects and the optical correction strategy to mitigate static and dynamic imperfections. For a small enough beam energy spread, we investigate the possibility to get a smaller vertical beam size, at the expense of a larger horizontal beam size, by re-optimising the final focus optics with chromatic correction mainly in the vertical plane. Firstly, we track the beam with MAD-X, with and without chromaticity correction, to estimate the optimum betax and betay values by rematching the linear optics, and cross-check and improve the rematching procedure with MAPCLASS. Then, we study the original design and an alternative simplified optical system, using a set of enlarged betax values, and optimize the sextupoles as a function of betay to minimize the vertical beam size for different assumptions on the energy spread.

TUPME031

Considerations for a Higgs Facility Based on Laser Wakefield Acceleration

plasma, laser, collider, electron

1643

S. Hillenbrand, A.-S. Müller
KIT, Karlsruhe, Germany
R.W. Aßmann, S. Hillenbrand, D. Schulte
CERN, Geneva, Switzerland

Laser Wakefield Accelerators have seen tremendous progress over the last decades. It is hoped that they will allow to significantly reduce the size and cost of a future liner collider. Based on scaling laws, laser-driven plasma accelerators are investigated as drivers for smaller scale facilities capable of producing Z and Higgs bosons.

TUPME040

TLEP: High-performance Circular e⁺e⁻ Collider to Study the Higgs Boson

polarization, cryogenics, collider, wiggler

1658

M. Koratzinos, O. Brunner, A.C. Butterworth, J.R. Ellis, P. Janot, E. Jensen, J.A. Osborne, F. Zimmermann
CERN, Geneva, Switzerland
R. Aleksan
CEA/DSM/IRFU, France
A.P. Blondel
DPNC, Genève, Switzerland
M. Zanetti
MIT, Cambridge, Massachusetts, USA

The recent discovery of a light Higgs boson has opened up considerable interest in circular e⁺e⁻ Higgs factories around the world. We report on the progress of the “TLEP3” concept since last year. Two options are considered: LEP3, a 240 GeV centre-of-mass (Ecm) e⁺e⁻ machine in the LHC tunnel with cost only a fraction of the cost of an equivalent linear collider, due to the use of existing infrastructure and the two general-purpose LHC detectors, and TLEP, an e⁺e⁻ machine in a new 80 km tunnel that can operate up to an Ecm of 350 GeV. Both concepts enjoy the extensive know-how on circular colliders and how to deliver their design luminosity, and the existence of up to four interaction points. The attainable luminosities are 10³⁴/cm²/s and 5x10³⁴/cm²/s per interaction point for LEP3 and TLEP respectively. Both machines can operate as Tera-Z and Mega-W boson factories, giving decisive opportunities for over-constraining the electroweak sector of the Standard Model. The technical challenges and possible ways to improve the performance further will be discussed.

TUPME049

Status of the Exploration of an Alternative CLIC First Energy Stage Based on Klystrons

klystron, linac, linear-collider, collider

1676

D. Schulte, A. Grudiev, P. Lebrun, G. McMonagle, I. Syratchev, W. Wuensch
CERN, Geneva, Switzerland

The Compact Linear Collider is based on a two-beam scheme to accelerate the main, colliding beams. This scheme allows to reach very high centre-of-mass energies. At low collision energies the main beams could be accelerated by powering the accelerating structures with X-band instead of a second beam. We explore this option and indicate the parameters and conceptual design.

TUPME051

CLIC Final Focus System Alignment and Magnet Tolerances

quadrupole, sextupole, feedback, linear-collider

1682

J. Snuverink, J. Barranco, H. Garcia, Y.I. Levinsen, D. Schulte, R. Tomás
CERN, Geneva, Switzerland

The design requirements for the magnets in the Compact Linear Collider (CLIC) Final Focus System (FFS) are very stringent. In this paper the sensitivity for the misalignment and the magnetic imperfections for the different magnets in the FFS and the crab cavity are presented. Possible mitigation methods are discussed.

TUPME054

Experimental Study of the Effect of Beam Loading on RF Breakdown Rate in CLIC High-gradient Accelerating Structures

linac, beam-loading, optics, beam-losses

1691

F. Tecker, R. Corsini, M. Dayyani Kelisani, S. Döbert, A. Grudiev, O. Kononenko, S. Lebet, J.L. Navarro Quirante, G. Riddone, I. Syratchev, W. Wuensch
CERN, Geneva, Switzerland
A. Solodko
JINR, Dubna, Moscow Region, Russia

RF breakdown is a key issue for the multi-TeV high-luminosity e⁺e⁻ Compact Linear Collider (CLIC). Breakdowns in the high-gradient accelerator structures can deflect the beam and decrease the desired luminosity. The limitations of the accelerating structures due to breakdowns have been studied so far without a beam present in the structure. The presence of the beam modifies the distribution of the electrical and magnetic field distributions, which determine the breakdown rate. Therefore an experiment has been designed for high power testing a CLIC prototype accelerating structure with a beam present in the CLIC Test Facility (CTF3). A special beam line allows extracting a beam with nominal CLIC beam current and duration from the CTF3 linac. The paper describes the beam optics design for this experimental beam line and the commissioning of the experiment with beam.

TUPME059

Collisional Effects in Particle-in-Cell Beam-Beam Simulations

emittance, simulation, collider, proton

1700

S. Paret, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
Self-consistent particle tracking simulations (strong-strong) can be used to investigate the deterioration of colliding beams in a storage ring. However, the use of a small number of macroparticles copmared to the real number of particles magnifies the collisional effects and causes numerical noise. In particular, predictions of the emittance lifetime suffer from this numerical noise. In order to produce usable emittance predictions, the contribution of numerical noise to the simulated emittance growth has to be known. In this paper, we apply a diffusion model to strong-strong beam-beam simulations to study the numerical noise driven emittance growth. The scaling of emittance growth with numerical and physical parameters is discussed.

TUPME060

Tune Studies with Beam-Beam Effects in LHC

emittance, resonance, simulation, collider

1703

S. Paret, J. Qiang
LBNL, Berkeley, California, USA
R. Alemany-Fernandez, X. Buffat, R. Calaga, K. Cornelis, M. Fitterer, R. Giachino, W. Herr, A. Macpherson, G. Papotti, T. Pieloni, S. Redaelli, F. Roncarolo, M. Schaumann, R. Suykerbuyk, G. Trad
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
In high brightness colliders, the tune spread due to the collisions has a significant impact on the quality of the beams. The impact of the working point on emittance growth and beam lifetime has been observed in beam experiments in LHC. Strong-strong beam-beam simulations that were accomplished to better understand such observations are shown. Compared to experiments, wide ranged parameter scans can be done easily. Tune footprints and scans of the emittance growth obtained from simulations are discussed. Three cases are considered: Very high intensity, moderate intensity and collisions with separated beams.

TUPWA015

The Study of Bunch Lengthening in Electron Storage Ring

impedance, synchrotron, storage-ring, electron

1757

Y. Li, L. Wang, Y. Zhang
IHEP, Beijing, People's Republic of China

The bunch length of electron storage ring of BEPCII was measured repeatedly during steady synchronous mode and streak camera was calibrated well. From the bench lengthening , the coupling impedance of the whole ring was estimated, which was according with theoretic impedance budget . Meanwhile, the small ap optics for improving the luminosity was feasible in collision mode form synchronous result .

TUPWA045

Longitudinal Space Charge Effects in the CLIC Drive Beam

space-charge, simulation, quadrupole, lattice

1811

R.L. Lillestøl, S. Döbert, A. Latina, D. Schulte
CERN, Geneva, Switzerland
E. Adli, K.N. Sjobak
University of Oslo, Oslo, Norway

The CLIC main beam is accelerated by rf power generated from a high-intensity, low-energy electron drive beam. The accelerating fields are produced in Power Extraction and Transfer Structures, and are strongly dependent on the drive beam bunch distribution, as well as other parameters. We investigate how longitudinal space charge affects the bunch distribution and the corresponding power production, and discuss how the bunch length evolution can affect the main beam. We also describe the development of a Particle-in-Cell space charge solver which was used for the study.

WEPWO045

RF Multipolar Characterization of the Latest LHC Deflecting Cavities

cavity, multipole, dipole, extraction

2402

M. Navarro-Tapia, R. Calaga, A. Grudiev
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Deflecting cavity geometries considered for the Large Hadron Collider (LHC)crab scheme lack axial symmetry resulting in non-zero higher-order components of the deflecting field. A formalism to express the higher-order multipoles was developed and applied on previous cavity designs to characterize their influence on the beam stability. In this paper, the radio frequency (RF) multipoles are numerically estimated for the latest cavity geometries and compared to the older versions. A sensitivity study is carried to understand the numerical error levels and define mechanical tolerances.

WEPWO050

Mechanical Study of 400 MHz Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade

cavity, simulation, vacuum, electron

2417

B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu
BNL, Upton, Long Island, New York, USA
L. Alberty Vieira, R. Calaga
CERN, Geneva, Switzerland
T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA

A prototype double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. A finite element model is used to simulate the mechanical properties of the crab cavity. The results are presented and a reinforcement concept is proposed to meet the safety requirements. The reinforcement components, as well as the cavity, are presently being fabricated at Niowave Inc.

WEPWO051

Manufacture of a Compact Prototype 4R Crab Cavity for HL-LHC

cavity, niobium, vacuum, electron

2420

G. Burt, B.D.S. Hall, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
L. Alberty Vieira, R. Calaga, O. Capatina
CERN, Geneva, Switzerland
C.H. Boulware, D. Gorelov, T.L. Grimm, C. Krizmanich, T.S. Lamie
Niowave, Inc., Lansing, Michigan, USA
C. Hill, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.A. Rimmer, H. Wang
JLAB, Newport News, Virginia, USA

Funding: This work has been funded by the EU through EUCARD and HiLumi and by STFC via the Cockcroft Institute.
A prototype compact SRF deflecting cavity has been manufactured for LHC. The base of the cavity has been machined out of large grain niobium ingot to allow the manufacture of the complex rod profile. Stiffening rods have been used to increase the mechanical strength of the outer can. Details of the cavity design and manufacture will be discussed.

WEPEA047

Dynamic Aperture Performance for Different Collision Optics Scenarios for the LHC Luminosity Upgrade

optics, multipole, dynamic-aperture, injection

2609

M. Giovannozzi, R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland
A. Chancé, B. Dalena, J. Payet
CEA/IRFU, Gif-sur-Yvette, France
K.M. Hock, M. Korostelev, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The ATS[1] optics solution for the HL-LHC offers the possibility of different collision optics, with a β^* as small as 10 cm in both transverse planes, or with a β^* aspect ratio of up to 4 pushing β^* to even smaller value (5cm) in the parallel separation plane while relaxing it (20 cm) in the crossing plane. The latter configuration features two possible options for alternated orientations of the crossing plane in the two high luminosity insertions, both considered in this study. In this paper we study the impact of few selected field imperfection models of the new magnets foreseen for the upgrade through tracking simulations and scaling laws.
[1] S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA049

Analysis of the Non-linear Fringe Effects of Large Aperture Triplets for the HL LHC Project

quadrupole, dipole, simulation, optics

2615

A.V. Bogomyagkov, E.B. Levichev, P.A. Piminov
BINP SB RAS, Novosibirsk, Russia
A. Chancé, B. Dalena, J. Payet
CEA/IRFU, Gif-sur-Yvette, France
R. De Maria, S.D. Fartoukh, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The HL-LHC project relies on large aperture quadrupoles which are compatible with the very large beam sizes in the inner triplets resulting from the strong reduction of β^*. As a result the beam is much more sensitive to non-linear perturbations in this region, such as those induced by the fringe fields of the low-beta quadrupoles. The spatial extension of these fringe fields increases as well more or less linearly with the coil aperture, which is an additional motivation to analyse this aspect in detail in the framework of the High Luminosity LHC design study. This paper will quantify this effect both by direct analytical estimates using first order Hamiltonian perturbation theory, and via numerical studies thanks to the dedicated implementation of a fringe field symplectic integrator in SixTrack.

WEPEA050

Analysis of Possible Functional Forms of the Scaling Law for Dynamic Aperture as a Function of Time

dynamic-aperture, beam-losses, simulation, lattice

2618

M. Giovannozzi, R. De Maria, F. Lang
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
In recent studies, the evolution of the dynamic aperture with time has been fitted with a simple scaling law based on a limited number of free parameters. In this paper, different approaches to improve the numerical stability of the fit are presented, together with a new functional form. The results are discussed in details and applied to a set of numerical simulations for the LHC.

WEPEA058

LSS Layout Optimizations for Low-beta Optics for the HL-LHC

quadrupole, optics, sextupole, chromatic-effects

2639

B.J. Holzer, R. De Maria
CERN, Geneva, Switzerland
R. Appleby, L.N.S. Thompson
UMAN, Manchester, United Kingdom
L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
The High Luminosity LHC (HL-LHC) project aims to upgrade the existing LHC to a peak luminosity of the order 10³⁵cm^-2s⁻¹, while retaining as much of the nominal layout and hardware as possible. The current baseline for this upgrade is the use of the Achromatic Telescopic Squeeze (ATS) concept, which allows mini-Beta squeeze in IRs 1 and 5 (ATLAS and CMS respectively) far below that possible with nominal optics. However it is useful to both explore the parameter space of the ATS scheme while also attempting to push the boundaries of the nominal layout. This paper presents a study into maximising optical flexibility of the nominal LHC Long Straight Sections (LSSs) around IPs 1 and 5. This involves replacing, moving or adding magnets within the LSS to investigate feasibility of exploiting a more conventional optical scheme than the ATS scheme. In particular the option of replacing single LSS quadrupoles with doublets is explored. The study also looks at making similar changes to the LSS while also implementing the ATS scheme, to further explore the ATS parameter space with the benefit of experience gained into flexibility of a modified nominal LHC optical scheme.

WEPEA059

Study of the Impact of Fringe Fields of the Large Aperture Triplets on the Linear Optics of the HL-LHC

optics, quadrupole, collider, focusing

2642

B.J. Holzer, R. De Maria, S. Russenschuck
CERN, Geneva, Switzerland
R. Appleby, S. Kelly, M.B. Thomas, L.N.S. Thompson
UMAN, Manchester, United Kingdom
L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
High-luminosity hadron colliders such as the High Luminosity LHC (HL-LHC) project place demanding requirements on existing and new magnet technology. The very low β^* achieved by the Achromatic Telescopic Squeeze (ATS) optics scheme* for the HL-LHC in particular, requires large apertures in the high gradient Nb3Sn final focusing inner triplet triplet. Such magnets have extended fringe fields which perturb the linear and non-linear optics. This paper presents results of studies into the liner optics of the LHC using a range of fringe field models, including measurements of fringe fields from prototype magnets, and presents calculations of the beta-beating in the machine. Furthermore a similar study is presented on the nominal LHC optics, which uses final focus quadrupoles of higher gradient but significantly smaller aperture.
* S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for
LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA060

Plans for the Upgrade of CERN's Heavy Ion Complex

ion, injection, linac, acceleration

2645

D. Manglunki, M. E. Angoletta, H. Bartosik, A. Blas, D. Bodart, M.A. Bodendorfer, T. Bohl, J. Borburgh, E. Carlier, J.-M. Cravero, H. Damerau, L. Ducimetière, A. Findlay, R. Garoby, S.S. Gilardoni, B. Goddard, S. Hancock, E.B. Holzer, J.M. Jowett, T. Kramer, D. Kuchler, A.M. Lombardi, Y. Papaphilippou, S. Pasinelli, R. Scrivens, G. Tranquille
CERN, Geneva, Switzerland

To reach a luminosity higher than 6×10²⁷ Hz/cm² for Pb-Pb collisions, as expected by the ALICE experiment after its upgrade during the 2nd Long LHC Shutdown (LS2), several upgrades will have to be performed in the CERN accelerator complex, from the source to the LHC itself. This paper first details the present limitations and then describes the strategy for the different machines in the ion injector chain. Both filling schemes and possible hardware upgrades are discussed.

WEPEA061

The First LHC p-Pb run: Performance of the Heavy Ion Production Complex

ion, proton, heavy-ion, injection

2648

D. Manglunki, M. E. Angoletta, H. Bartosik, G. Bellodi, A. Blas, M.A. Bodendorfer, T. Bohl, C. Carli, E. Carlier, S. Cettour Cave, K. Cornelis, H. Damerau, A. Findlay, S.S. Gilardoni, S. Hancock, J.M. Jowett, D. Kuchler, M. O'Neil, Y. Papaphilippou, S. Pasinelli, R. Scrivens, G. Tranquille, B. Vandorpe, U. Wehrle, J. Wenninger
CERN, Geneva, Switzerland

TThe first LHC proton-ion run took place in January-February 2013; it was the first extension to the collider programme, as this mode was not included in the design report. This paper presents the performance of the heavy ion and proton production complex, and details the issues encountered, in particular the creation of the same bunch pattern in both beams.

WEPEA064

SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers

coupling, simulation, injection, synchrotron

2657

A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, O. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.

WEPEA067

Beam Optics Measurements through Turn by turn Beam Position Data in the SLS

betatron, storage-ring, optics, positron

2663

P. Zisopoulos, Y. Papaphilippou
CERN, Geneva, Switzerland
A. Streun
PSI, Villigen PSI, Switzerland
V.G. Ziemann
Uppsala University, Uppsala, Sweden

Refined Fourier analysis of turn-by-turn (TBT) transverse position data measurements can be used for determining several beam properties of a ring, such as transverse tunes, optics functions, phases, chromatic properties and coupling. In particular, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm is used to analyze TBT data from the Swiss Light Source (SLS) storage ring in order to estimate on and off-momentum beam characteristics. Of particular interest is the potential of using the full position information within one turn in order to measure beam optics properties.

WEPEA071

Performance Limitations in the Lhc Due to Parasitic Beam-Beam Encounters - Parameter Dependence, Scaling, and Pacman Effects

dynamic-aperture, beam-beam-effects, emittance, target

2672

T. Pieloni
EPFL, Lausanne, Switzerland
X. Buffat, R. Calaga, R. Calaga, R. Giachino, W. Herr, E. Métral, G. Papotti, G. Trad
CERN, Geneva, Switzerland
D. Kaltchev
TRIUMF, Vancouver, Canada

We studied possible limitations due to the long-range beam-beam effects in the LHC. With a large number of bunches and collisions in all interaction points, we have reduced the crossing angles (separation) to enhance long-range beam-beam effects to evaluate their influence on dynamic aperture and losses. Different β^*, number of bunches and intensities have been used in several dedicated experiments and allow the test of the expected scaling laws.

WEPEA076

Comparison of Taylor Maps with Radio Frequency Multipoles in a Thin Lens 6D Tracking Code

cavity, multipole, collider, hadron

2687

D.R. Brett, R. Appleby
UMAN, Manchester, United Kingdom
J. Barranco, R. De Maria, R. Tomás
CERN, Geneva, Switzerland

Funding: HiLumi LHC Design Study is part of the High Luminosity LHC project and is part funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
SixTrack is a general purpose 6D thin lens tracking code used for dynamic aperture studies. In the high luminosity LHC upgrade it is proposed that crab cavities are used to enhance the luminosity. In this study, for the current proposed optics, we consider the use of RF multipoles and Taylor maps as methods to simulate crab cavity elements in the lattice.

WEPFI091

Design of a Normal-conducting RF-dipole Deflecting Cavity

cavity, dipole, simulation, extraction

2911

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
D. Li
LBNL, Berkeley, California, USA

In this paper we present a novel design of a CW normal conducting RF deflecting cavity. The cavity is designed into a dipole-like structure, resulting a high (R/Q)_transverse. The geometry at high H field is optimized to lower the surface peak power. We will show the design of a 325 MHz and 163 MHz cavity based on this structure and compare their performances with their superconducting counterparts.

THPPA03

The Development of China’s Accelerators I Have Experienced

proton, synchrotron, linac, radiation

3144

S.X. Fang
IHEP, Beijing, People's Republic of China

The development of China’s high energy accelerator for half a century falls into two stages, namely the first 20 hovering years (1958-1978) and the later 30 years of rapid development (from 1978 till now). I was lucky enough to have experienced the whole process, witnessed, and to some extent, joined in the decision-making, the projects approval, the designing, the development and construction of China's five large scientific facilities undertaken by the Institute of High Energy Physics in Beijing. A brief review is given of the previous stage of history regarding the consideration of China’s high energy accelerators in the first 20 years. A short presentation is also given of the later 30 years concerning the rapid development of the Beijing Electron-Positron Collider (BEPC and BEPCII), the completed BEPC-based Shanghai Synchrotron Radiation Facility (SSRF), the Chinese Spallation Neutron Source (CSNS) under construction, the high-intensity proton accelerator (ADS) used for nuclear waste transmutation and the proton therapy machine in the R&D stage.

Slides THPPA03 [6.015 MB]

THPFI049

Evaluation of the NEG Coating Saturation Level after 3 Years of LHC Beam Operation

vacuum, proton, ion, electron

3397

G. Bregliozzi, V. Baglin, J.M. Jimenez, G. Lanza, T. Porcelli
CERN, Geneva, Switzerland

The room temperature vacuum system of the Large Hadron Collider (LHC) at CERN system has been designed to ensure vacuum stability and beam lifetime of 100 h with nominal current of 0.56 A per beam at 7 TeV of energy. During last two years the LHC operated with proton beams at a maximum energy of 4 TeV, coasting for several hours each time, inducing high pressure due to different effects: synchrotron radiation, electron cloud and localized temperature increase. All these phenomena generated an important gas load from the vacuum chamber walls, which led in some cases to a partial or a total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG vacuum reactivation, it is necessary to take into account all these aspects and to regularly evaluate the saturation level of the NEG coating. This study analyses the saturation level of the NEG coated beam pipes in the LHC accelerator. Pressure reading variation without proton beams circulating are analysed and combined with laboratory studies of the NEG saturation behaviour and with Vacuum Stability Code (VASCO) simulations.

THPFI060

Development, Validation and Application of a Novel Method for Estimating the Thermal Conductance of Critical Interfaces in the Jaws of the LHC Collimation System

radiation, collimation, pick-up, target

3430

I. Leitão
CERN, Geneva, Switzerland

The motivation for this project arises from the difficulty in quantifying the manufacturing quality of critical interfaces in the water cooled jaws of the TCTP and TCSP (Target Collimator Tertiary Pickup and Target Collimator Secondary Pickup) collimators. These interfaces play a decisive role in the transfer of heat deposited by the beam towards the cooling system avoiding excessive deformation of the collimator. Therefore, it was necessary to develop a non-destructive method that provides an estimation of the thermal conductance during the acceptance test of the TCTP and TCSP jaws. The method is based on experimental measurements of temperature evolution and numerical simulations. By matching experimental and numerical results it is possible to estimate the thermal conductance in several sections of the jaw. A simplified experimental installation was built to validate the method, then a fully automatic Test-Bench was developed and built for the future acceptance of the TCTP/TCSP jaws which will be manufactured and installed in the LHC. This novel method has shown its validity and has become a decisive tool for the development of the new generation of LHC collimators.

THPME044

Fabrication and Test of a 1 M Long Single-aperture 11 T Nb3Sn Dipole for LHC Upgrades

dipole, sextupole, interaction-region, magnet-design

3609

A.V. Zlobin, N. Andreev, G. Apollinari, E.Z. Barzi, R. Bossert, G. Chlachidze, J. DiMarco, A. Nobrega, I. Novitski, D. Turrioni, G. Velev
Fermilab, Batavia, USA
B. Auchmann, M. Karppinen, L. Rossi, D. Smekens
CERN, Geneva, Switzerland

Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and European Commission under FP7 project HiLumi LHC, GA no.284404
The planned upgrade of the LHC collimation system includes two additional collimators to be installed in the dispersion suppressor areas around points 2, 3 and 7, and high luminosity interaction regions in points 1 and 5. The necessary longitudinal space for the collimators could be provided by replacing some 8.33 T NbTi LHC main dipoles with 11 T dipoles based on Nb3Sn superconductor and compatible with the LHC lattice and main systems. To demonstrate this possibility Fermilab and CERN have started in 2011 a joint R&D program with the goal of building by 2015 a 5.5-m long twin-aperture dipole prototype suitable for installation in the LHC. An important part of the program is the development and test a series of short single-aperture demonstration dipoles with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and ~20% margin. This paper describes the design features and test results of a 1-m long single-aperture Nb3Sn demonstrator dipole for the LHC collimation system upgrade.

THPWO077

Status and Plans for the Upgrade of the LHC Injectors

linac, injection, ion, extraction

3936

R. Garoby, H. Damerau, S.S. Gilardoni, B. Goddard, K. Hanke, A.M. Lombardi, D. Manglunki, M. Meddahi, B. Mikulec, L. Ponce, E.N. Shaposhnikova, R. Steerenberg, M. Vretenar
CERN, Geneva, Switzerland

The plans for preparing the LHC injectors to fulfill the needs of the LHC during the next decade have significantly progressed in 2012. Linac4 construction has passed major steps of pre-series fabrication. Hardware developments and beam studies have allowed refining the baseline actions to implement and the beam characteristics achievable at injection into the collider for protons as well as for Lead ions. These achievements are described in this paper, together with the updated project planning matched to the new schedule of the LHC.