Keyword: luminosity
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MOXBP01 The First Two Years of LHC Operation proton, ion, emittance, dipole 1
 
  • S. Myers
    CERN, Geneva, Switzerland
  
  The operational performance of the LHC machine both for proton and lead ion operation are reviewed for the period 2010 and up the present. The beam parameter path allowing the very high rate of collider performance is presented and discussed. The accelerator issues encountered and those somewhat surprisingly not encountered are also discussed. The short and longer term plans for the LHC are also briefly presented.  
slides icon Slides MOXBP01 [17.468 MB]  
 
MOPPC002 Local Chromatic Correction Scheme and Crab-waist Collisions for an Ultra-low β* at the LHC sextupole, optics, quadrupole, resonance 118
 
  • J.L. Abelleira, S. Russenschuck, R. Tomás, F. Zimmermann
    CERN, Geneva, Switzerland
  • J.L. Abelleira
    EPFL, Lausanne, Switzerland
  • C. Milardi, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • K. Ohmi
    KEK, Ibaraki, Japan
  • D.N. Shatilov
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579.
We discuss potential merits and the parameter range of interest for a possible crab-waist collision scheme at the LHC, and report preliminary optics studies of a local chromatic correction scheme with flat beams (βx*>>βy*), which could boost the LHC luminosity by about an order of magnitude and would also allow for crab-waist collisions. 		 
 
MOPPC003 Very Fast LHC Crab Cavity Failures and their Mitigation simulation, betatron, cavity, optics 121
 
  • T. Baer, R. Calaga, R. De Maria, S.D. Fartoukh, E. Jensen, R. Tomás, J. Tückmantel, J. Wenninger, B. Yee-Rendon, F. Zimmermann
    CERN, Geneva, Switzerland
  • T. Baer
    University of Hamburg, Hamburg, Germany
  
  For the high-luminosity LHC upgrade program (HL-LHC), the installation of crab cavities (CCs) is needed to compensate the geometric luminosity loss due to the crossing angle and for luminosity leveling [*]. The baseline is a local scheme with CCs around the ATLAS and CMS experiments. In a failure case (e.g. a control failure or arcing in the coupler), the voltage and/or phase of a CC can change significantly with a very fast time constant of the order of 1 to 10 LHC turns. This can lead to large, global betatron oscillations of the beam. The impact of CC failures on the beam dynamics is discussed and the results from dedicated simulations are presented. Mitigation strategies to limit the impact of CC failures to an acceptable level are proposed.
* F. Zimmermann and O. Brüning, “Parameter Space for the LHC High-Luminosity Upgrade”, IPAC'12, MOPPC005, May 2012. 		 
 
MOPPC005 Parameter Space for the LHC Luminosity Upgrade* target, emittance, optics, brightness 127
 
  • F. Zimmermann, O.S. Brüning
    CERN, Geneva, Switzerland
  
  Funding: Work supported by the European Commission under the FP7 Research Infrastructures projects EuCARD, grant agreement no. 227579, and HiLumi LHC, grant agreement no. 284404.
We review the parameter space for the high-luminosity upgrade of the LHC (HL-LHC). Starting from the luminosity targets and the primary limitations, e.g., long-range beam-beam effects, event pile up, electron cloud, turnaround time, intrabeam scattering, we determine the range for compatible beam parameters such as the beam intensity, bunch spacing, transverse and longitudinal emittances, bunch length, and IP beta functions required to meet the HL-LHC goals. A selection of a few possible parameter sets is presented for comparison and discussion. 		 
 
MOPPC010 Parametric Study of Optics Options for the HL-LHC Project optics, quadrupole, insertion, sextupole 142
 
  • R. De Maria
    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, cofunded by the DoE, USA and KEK, Japan.
The LHC Upgrade studies have been recently formalized into the High-Luminosity LHC (HL-LHC) project. The paper explores the parameter space in terms minimum beta star (flat and round), and luminosity leveling scenarios, constrained by the triplet gradient and aperture and still compatible with optics solutions based on the ATS scheme*. The limitations of the proposed solutions, essentially given by the preservation of the dynamic aperture in the presence of large beta-beating waves induced in the arcs by the squeezing scheme are investigated. The results will be combined in scaling laws benchmarked with existing fully developed scenarios.
* S. Fartoukh et al., "The Achromatic Telescopic Squeezing (ATS) scheme: from initial motivations to basic principles, and first demonstration at the LHC," these proceedings. 		 
 
MOPPC013 Optics and Lattice Optimizations for the LHC Upgrade Project optics, lattice, ion, insertion 151
 
  • B. Dalena
    CEA/IRFU, Gif-sur-Yvette, France
  • R. Appleby
    UMAN, Manchester, United Kingdom
  • A.V. Bogomyagkov
    BINP SB RAS, Novosibirsk, Russia
  • A. Chancé, J. Payet
    CEA/DSM/IRFU, France
  • R. De Maria, B.J. Holzer
    CERN, Geneva, Switzerland
  • A. Faus-Golfe, J. Resta-López
    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
  
  The luminosity upgrade of the LHC collider at CERN is based on a strong focusing scheme to reach lowest values of the beta function at the collision points. Several issues have to be addressed in this context, that are considered as mid term goals for the optimisation of the lattice and beam optics: Firstly a number of beam optics have been developed to establish a baseline for the hardware R&D, and to define the specifications for the new magnets that will be needed, in Nb3Sn and in NbTi technology. Secondly, the need for sufficient flexibility of the beam optics especially for smallest β* values has to be investigated as well as the need for a smooth transition between the injection and the collision optics. Finally the performance of the optics based on flat and round beams has to be compared and different ways have to be studied to optimise the chromatic correction, including the study of local correction schemes. This paper presents the status of this work, which is a result of an international collaboration, and summarises the main parameters that are foreseen to reach the HL-LHC luminosity goal.  
 
MOPPC017 Causes and Solutions for Emittance Blow-Up During the LHC Cycle emittance, injection, proton, feedback 160
 
  • M. Kuhn
    Uni HH, Hamburg, Germany
  • G. Arduini, B.J. Holzer, J.M. Jowett, V. Kain, F. Roncarolo, M. Schaumann, R. Versteegen, J. Wenninger
    CERN, Geneva, Switzerland
  
  Emittance measurements during the run 2011 indicated a blow-up of 20 % to 30 % from LHC injection to collisions. At the LHC design stage the total allowed emittance increase through the cycle was set to 7 %. One of the goals of the 2012 LHC run is therefore to understand and counteract the blow-up. Emittance growth measurements through the LHC cycle along with correlations with possible sources are presented in this paper. Solutions are proposed where possible. The emittance determination accuracy relies on the knowledge of the beam optics and on the present performance of the transverse profile monitors. Possible improvements of the diagnostics and of the related data analysis are also discussed.  
 
MOPPC022 Off-momentum Dynamic Aperture for Lattices in the RHIC Heavy Ion Runs lattice, ion, heavy-ion, emittance 175
 
  • Y. Luo, M. Bai, M. Blaskiewicz, W. Fischer, X. Gu, A. Marusic, T. Roser, S. Tepikian, 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.
In this article we calculate and compare the off-momentum dynamic aperture for lattices with different phase advances per FODO cell in the RHIC heavy ion runs. A lattice with an increased phase advance was adopted in 2008-2011 to reduce transverse emittance growth rates from intra-beam scattering. However, during these runs, a large beam loss was observed with longitudinal RF re-bucketing which increased the momentum spread. With operational transverse stochastic cooling in the 2011 RHIC heavy ion run, the transverse intra-beam scattering emittance growth was eliminated, and the beam loss during stores was determined by the off-momentum aperture and burn-off from luminosity. We investigate the possibilities to increase the off-momentum dynamic aperture that would lead to an increase in the integrated luminosity. 		 
 
MOPPC025 RHIC Polarized Proton Operation in Run 12 polarization, proton, emittance, acceleration 184
 
  • V. Schoefer, L. A. Ahrens, A. Anders, E.C. Aschenauer, G. Atoian, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, A. Dion, K.A. Drees, W. Fischer, C.J. Gardner, J.W. Glenn, X. Gu, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, R.L. Hulsart, A. 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, A. Poblaguev, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, 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
  
  Successful RHIC operation with polarized protons requires meeting demanding and sometimes competing goals for maximizing both luminosity and beam polarization. In Run 12 we sought to fully integrate into operation the many systems that were newly commissioned in Run 11 as well as to enhance collider performance with incremental improvements throughout the acceleration cycle. For luminosity maximization special attention was paid to several possible source of emittance dilution along the injector chain, in particular to optical matching during transfer between accelerators. Possible sources of depolarization in the AGS and RHIC were also investigated including the effects of local coupling and low frequency (10 Hz) oscillations in the vertical equilibrium orbit during the RHIC ramp. The results of a fine storage energy scan made in an effort to improve store polarization lifetime are also reported in this note.  
 
MOPPC027 Synchro-Betatron Effects in the Presence of Large Piwinski Angle and Crab Cavities at the HL-LHC betatron, simulation, coupling, damping 190
 
  • S.M. White
    BNL, Upton, Long Island, New York, USA
  • R. Calaga
    CERN, Geneva, Switzerland
  • R. Miyamoto
    ESS, Lund, Sweden
  
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The reduction of beta-star at the collision points for the high luminosity LHC (HL-LHC) requires an increment in the crossing angle to maintain the normalized beam separation to suppress the effects of long-range beam-beam interactions. However, increase in crossing angle may give rise to synchro-betatron resonances which may negatively affect the beam emittance and lifetime. 6D weak-strong and strong-strong simulations are performed to study the effect of synchro-betatron resonances in the context of the HL-LHC layout and its suppression via crab crossing. 		 
 
MOPPC034 Use of Helical Transport Channels for Bunch Recombination simulation, collider, emittance, focusing 205
 
  • D.V. Neuffer, K. Yonehara
    Fermilab, Batavia, USA
  • C.M. Ankenbrandt, C. Y. Yoshikawa
    Muons, Inc, Batavia, USA
  
  Cooling scenarios for a high-luminosity Muon Collider require bunch recombination for optimal luminosity. In this paper we describe a new method for bunch recombination. We combine the high-chronicity of a helical transport channel (HTC) with the high-frequency bunching and phase-energy rotation concept (time-reversed) to obtain a compact bunch recombination system adapted to a muon collider scenario. We first present an idealized 1-D system with multiple chronicity transports. We then implement the concept in a single-chronicity channel, obtaining bunch recombination of 13 200MHz-spaced bunches to a single collider-ready bunch within a compact transport with modest rf requirements. That example is demonstrated within G4BL 3-D simulations. Variations and adaptations for different recombination requirements are discussed.  
 
MOPPC074 Evolution of MAD-X in the Framework of LHC Upgrade Studies multipole, simulation, optics, quadrupole 304
 
  • A. Latina, L. Deniau
    CERN, Geneva, Switzerland
  
  The design efforts for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will require significant extensions of the MAD-X code widely used for designing and simulating particles accelerators. For this purpose, several new capabilities have been added to the code, namely the possibility to simulate crab cavities for crossing angle compensation, with their imperfections; the selective introduction of thick quadrupole elements for particles tracking, improving the previous implementation entirely based on thin-lenses; and the upgrade of the interface to SixTrack used for distributed tracking with, e.g., LHC@home. These changes are framed into a global redesign of the MAD-X architecture meant to consolidate its structure, improve its performances, and increase its flexibility. Such improvements are described in details in the present paper.  
 
MOPPD058 LHC Abort Gap Cleaning Studies during Luminosity Operation kicker, injection, emittance, beam-losses 496
 
  • E. Gianfelice-Wendt
    Fermilab, Batavia, USA
  • W. Bartmann, A. Boccardi, C. Bracco, E. Bravin, B. Goddard, W. Höfle, D. Jacquet, A. Jeff, V. Kain, M. Meddahi, F. Roncarolo, J.A. Uythoven, D. Valuch
    CERN, Geneva, Switzerland
  
  The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both Abort Gap (AG) and buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation as well. In this paper the results of experimental studies performed in October 2011 are presented.  
 
MOPPD062 Aperture Measurements in the LHC Interaction Regions injection, emittance, optics, resonance 508
 
  • S. Redaelli, M.C. Alabau Pons, R.W. Assmann, R. Bruce, M. Giovannozzi, G.J. Müller, M. Pojer, J. Wenninger
    CERN, Geneva, Switzerland
  
  The aperture of the LHC interaction regions is crucial for the LHC performance because it determines the smaller β* that can be achieved. The aperture has been measured at a maximum energy of 3.5 TeV and at different β* values, following optimized procedure to allow safe measurements at high energy. In this paper, the results of these aperture measurements, which are used as a reference for β* reach and crossing scheme estimates at the LHC interaction points, are presented.  
 
MOPPR046 CLIC Luminosity Monitoring photon, simulation, monitoring, background 885
 
  • A. Apyan, L.C. Deacon, E. Gschwendtner, T. Lefèvre
    CERN, Geneva, Switzerland
  • R. Appleby, S.C. Tygier
    UMAN, Manchester, United Kingdom
  
  The CLIC post-collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14MW to the main beam dump. Luminosity monitoring for CLIC is based on high energy muons produced by bremsstrahlung photons in the main dump. Threshold Cherenkov counters are proposed for the detection of these muons. The expected rates and layout for these detectors is presented. Another method for luminosity monitoring is to directly detecting the bremsstrahlung photons in the post-collision line; Full Monte Carlo simulation has been performed to address its feasibility.  
 
MOPPR076 Using the BRAN Luminosity Detectors for Beam Emittance Monitoring During LHC Physics Runs emittance, monitoring, interaction-region, proton 966
 
  • A. Ratti, H.S. Matis, M. Placidi, W.C. Turner
    LBNL, Berkeley, California, USA
  • E. Bravin
    CERN, Geneva, Switzerland
  • T.E. Lahey
    SLAC, Menlo Park, California, USA
  • E.S.M. McCrory
    Fermilab, Batavia, USA
  • R. Miyamoto
    ESS, Lund, Sweden
  • S.M. White
    BNL, Upton, Long Island, New York, USA
  
  Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The BRAN Ionization Chambers installed at the IP1 and IP5 Interaction Points of the LHC provide a relative measurement of the total and bunch-by-bunch luminosities. This information, combined with the logged bunch charges from a fast BCT monitor, offers the possibility of evaluating the Interaction Area in collision for each of the colliding bunch pairs and monitor its time evolution. A Graphic User Interface (GUI) has been implemented to display the interaction area of the proton bunches interacting in IP1 and IP5 during each of the Physics Runs in the attempt of displaying the contribution to the Luminosity time decay originating from possible emittance blow-up when operating the Accelerator close to the beam-beam limit. Early results confirm the ability to characterize the bunch by bunch emittance behavior during the store and study possible differences among bunches in the same fill. 		 
 
TUYA03 Performance and Prospects of BEPCII coupling, optics, feedback, injection 1030
 
  • Q. Qin
    IHEP, Beijing, People's Republic of China
  
  BEPCII, the upgrade project of Beijing Electron Positron Collider (BEPC), has been put into operation for both high energy physics experiments as well as synchrotron radiation application since its completion in 2009. The peak luminosity reaches 6.5*1032 cm-2 s-1 at 1.89 GeV with e+e− collisions of each beam current 700 mA. The collider operates for dedicated synchrotron radiation mode with 250 mA electron beams at 2.5 GeV. The performance of BEPCII should be reported and the measures to upgrade its luminosity described.  
slides icon Slides TUYA03 [5.529 MB]  
 
TUPPC018 Estimation of Orbit and Optics Distortion of SuperKEKB by Tunnel Deformation emittance, quadrupole, optics, coupling 1197
 
  • A. Morita, H. Koiso, Y. Ohnishi, K. Oide, H. Sugimoto
    KEK, Ibaraki, Japan
  
  The tunnel which was used for the KEKB B-factory is reused for the accelerator tunnel of the SuperKEKB. The total vertical displacement of the tunnel subsidence reached almost 30mm during 10 years KEKB operation. In order to operate the SuperKEKB which might be more delicate machine than the previous KEKB B-factory, we are evaluating the optics distortion by the tunnel deformation and studying the machine performance after the orbit and optics correction. We report the estimation of the machine performance degradation by the tunnel subsidence and the requirement of the correction.  
 
TUPPC033 Random Walk Optimization in Accelerators: Vertical Emittance Tuning at SLS target, emittance, quadrupole, controls 1230
 
  • M. Aiba, M. Böge, N. Milas, A. Streun
    Paul Scherrer Institut, Villigen, Switzerland
  
  The operation of a high performance accelerator is realized only when several beam based corrections are implemented. These corrections are, however, limited by measurement errors as the correction approaches the ideal value. To overcome this limitation, we investigate the application of a random walk (RW) optimization specifically to minimize the vertical emittance at the SLS. A systematic minimization is performed by measuring linear coupling and spurious vertical dispersion and correcting them using 36 skew quadrupole correctors. On the other hand, the minimization can be performed by simply applying a multi-variable optimization from the mathematics point of view, where the best combination of skew corrections is to be found. The measured vertical beam size is available as a stable target function of the minimization even at very low vertical emittance. Although RW and other algorithms are implemented into various accelerator computer codes, it is interesting to apply this concept to the real machine, where measurement errors are unavoidable and may prohibit systematic minimization based on a machine model. Possible applications of the technique in general are also discussed.  
 
TUPPC056 Optics Measurements and Corrections at RHIC optics, quadrupole, proton, lattice 1299
 
  • M. Bai, J.N. Aronson, M. Blaskiewicz, Y. Luo, V.H. Ranjbar, G. Robert-Demolaize, S.M. White
    BNL, Upton, Long Island, New York, USA
  • G. Vanbavinckhove
    CERN, Geneva, Switzerland
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The further improvement of RHIC luminosity performance requires more precise understanding of the RHIC modeling. Hence, it is necessary to minimize the beta-beat, deviation of measured beta function from the calculated beta functions based on an model. The correction of beta-beat also opens up the possibility of exploring operating RHIC polarized protons at a working point near integer, a preferred choice for both luminosity as well as beam polarization. The segment-by-segment technique for reducing beta-beat demonstrated in the LHC operation for reducing the beta-beat was first tested in RHIC during its polarized proton operation in 2011. It was then fully implemented during the RHIC polarized proton operation in 2012. This paper reports the commissioning results. Future plan is also presented. 		 
 
TUPPC061 Commissioning of a beta∗ Knob for Dynamic IR Correction at RHIC optics, quadrupole, feedback, insertion 1314
 
  • G. Robert-Demolaize, A. Marusic, S. Tepikian, S.M. White
    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 addition to the recent optics correction technique demonstrated at CERN and applied at RHIC, it is important to have a separate tool to control the value of the beta functions at the collision point (beta∗). This becomes even more relevant when trying to reach high level of integrated luminosity while dealing with emittance blow-up over the length of a store, or taking advantage of compensation processes like stochastic cooling. Algorithms have been developed to allow modifying independently the beta function in each plane for each beam without significant increase in beam losses. The following reviews the principle of such algorithms and their experimental implementation as a dynamic beta-squeeze procedure. 		 
 
TUPPC078 Proposal of an Inverse Logarithm Scaling Law for the Luminosity Evolution collider, emittance, dynamic-aperture, hadron 1353
 
  • M. Giovannozzi
    CERN, Geneva, Switzerland
  • C.H. Yu
    IHEP, Beijing, People's Republic of China
  
  A scaling law for the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers, about ten years ago. It was showed that dynamic aperture has a logarithmic dependence on time, which would be suggested by some fundamental theorems of the theory of dynamical systems. Such a scaling law was recently extended also to the intensity evolution in a storage ring. In this paper, inspired by these results, and inverse logarithm scaling law for the luminosity in a circular collider is proposed. The law is then tested against the data from the LHC physics runs and also with some examples from other machines. The results are presented and discussed in details.  
 
TUPPC091 Simulation of Colliding Beams with Feedback in LHC simulation, emittance, feedback, kicker 1374
 
  • S. Paret, J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: This work supported partially by the US LHC Accelerator Research Program (LARP) of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Beam-beam effects impose restrictions on beam and beam optical parameters as they may degrade the luminosity and the emittance or cause coherent instabilities and particle loss. In the planned High Luminosity Large Hadron Collider (HL-LHC), beam-beam effects will significantly affect the beams because of unprecedented beam parameters and new features like crab cavities or elliptical beam cross sections at the interaction points. Noise from various sources can further worsen the situation. Therefore investigations are required to identify limitations of possible HL-LHC layouts. The impact of beam-beam effects on the beam dynamics is investigated by virtue of particle tracking simulations. Using the code BeamBeam3D and the strong-strong collision model, simulations including perturbations by noise and LHC's feedback system, an important means to mitigate transverse emittance growth due to coherent beam excitation, were carried out. The impact of numerical noise on the emittance in simulations and the state of the feedback modeling are presented. 		 
 
TUPPC103 Ion Bunch Length Effects on the Beam-beam Interaction and its Compensation in a High-luminosity Ring-ring Electron-ion Collider electron, proton, ion, simulation 1401
 
  • C. Montag, W. Fischer, A. Oeftiger
    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.
One of the luminosity limits in a ring-ring electron-ion collider is the beam-beam effect on the electrons. In the limit of short ion bunches, simulation studies have shown that this limit can be significantly increased by head-on beam-beam compensation with an electron lens. However, with an ion bunch length comparable to the beta-function at the IP in conjunction with a large beam-beam parameter, the electrons perform a sizeable fraction of a betatron oscillation period inside the long ion bunches. We present recent simulation results on the compensation of this beam-beam interaction with multiple electron lenses. 		 
 
TUPPR007 Beam Background and MDI Design for SuperKEKB/Belle-II background, scattering, neutron, radiation 1825
 
  • H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama
    KEK, Tsukuba, Japan
  • H. Nakano
    Tohoku University, Graduate School of Science, Sendai, Japan
  
  The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 ab−1 before the shutdown in June 2010. We have started upgrading both the accelerator and the detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8×1035 cm−2 s−1. With the increased luminosity, the beam background will be severe. The development of Machine- Detector Interface (MDI) design is crucial to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB, such as Touschek-scattering, Beam-gas scattering, radiative Bhabha process, etc.. We will also present our countermeasures against them, such as collimators to stop scattered beam particles, Tungsten shield to protect inner detectors from shower particles, and dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.  
 
TUPPR008 One 233 km Tunnel for Three Rings: e+e-, p-pbar, and μ++μ− collider, dipole, emittance, lattice 1828
 
  • G.T. Lyons, L.M. Cremaldi, A. Datta, M. Duraisamy, T.H. Luo, D.J. Summers
    UMiss, University, Mississippi, USA
  
  Funding: Supported by DE-FG05-91ER40622
In 2001, a cost analysis was conducted to build a 233 km circumference tunnel in northern Illinois for a Very Large Hadron Collider (VLHC). Here we outline the implementations of e+e−, proton anti-proton, and μ++ μ− collider rings in such a tunnel using recent technological innovations. The 500 GeV e+e− collider employs a Crab Waist Crossing, ultra low emittance damped bunches, a vertical IP focal length of 0.06 cm, 12 GV of superconducting RF, and 0.026 Tesla low coercivity, grain oriented silicon steel/concrete dipoles. The 40 TeV proton anti-proton collider uses the high intensity Fermilab anti-proton source, exploits high cross sections for proton anti-proton production of high mass states, and uses 2 Tesla 0.005% ultra low carbon steel/YBCO superconductor magnets run with liquid neon. The 40 TeV muon ring ramps the 2 Tesla superconducting magnets at 8 Hz every 0.4 seconds, uses 250 GV of superconducting RF to accelerate muons from 2 to 20 TeV in 72 orbits with 72% survival, and mitigates neutrino radiation with a phase shifting, roller coaster FODO lattice.*
* G. T. Lyons, http://arxiv.org/pdf/1112.1105 		 
 
TUPPR017 Nonlinear Post-Linac Energy Collimation System for the Compact Linear Collider sextupole, collimation, octupole, simulation 1846
 
  • J. Resta-López, A. Faus-Golfe
    IFIC, Valencia, Spain
  
  Funding: FPA2010-21456-C02-01
The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed to provide protection of the Beam Delivery System (BDS) against off-energy and mis-steered beams. The conventional baseline design consists of a two stage spoiler-absorber scheme. The CLIC energy collimators are required to withstand the impact of a full bunch train. This condition makes the energy collimator design very challenging, since the collimators have to deal with a total beam power of 14 MW at nominal energy and intensity. The increase of the transverse spot size at the collimators using nonlinear magnets could be a potential solution to guarantee the survivability of the collimators. In this paper we present an alternative nonlinear optics design for the CLIC energy collimation system. Possibilities for its optimization are discussed in view of performance simulation results. 		 
 
TUPPR022 Traditional Final Focus System for CLIC lattice, collider, linear-collider, quadrupole 1858
 
  • H. Garcia, A. Latina, R. Tomás
    CERN, Geneva, Switzerland
  • H. Garcia
    UPC, Barcelona, Spain
  
  Next generation linear colliders needs a very strong focalisation to reach nanometer beam size at the Interaction Point. This task and the chromatic correction generated by the strong lenses is done by the Final Focus System. A traditional Final Focus System based on dedicated chromaticity correction sections is presented as an alternative for CLIC Final Focus. The scheme of the lattice is shown and some tolerances in the Final Doublet are calculated. A systematic tuning using Simplex algorithm and sextupole knobs is performed. The complete comparison to the Local Chromaticity correction scheme is presented.  
 
TUPPR024 CLIC Recombination Scheme for the Low Energy Operation Mode factory, acceleration, collider, linac 1864
 
  • A. Gerbershagen, D. Schulte
    CERN, Geneva, Switzerland
  • P. Burrows
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  
  The CLIC recombination scheme is a concept of multiplication of the drive beam frequency in order to generate a 12 GHz RF wave for the main beam acceleration. CLIC is designed to be operated in nominal and in low energy modes. The low energy operation modes require the train length to be increased by different factors in order to maintain the same level of luminosity. Also the number of initial trains that are merged to form each final train is changed. The combination scheme must be able to accommodate and recombine both long and short trains for nominal and low energy CLIC operation modes. The recombination hence becomes a non-trivial process and makes the correction of the errors in the drive beam more challenging. The present paper describes in detail the recombination process and its consequences.  
 
TUPPR028 Recent Improvements in the Orbit Feedback and Ground Motion Mitigation Techniques for CLIC quadrupole, simulation, feedback, ground-motion 1876
 
  • J. Snuverink, J. Pfingstner, D. Schulte
    CERN, Geneva, Switzerland
  
  The Compact Linear Collider (CLIC) accelerator has strong stability requirements on the position of the beam. In particular, the beam position will be sensitive to ground motion. A number of mitigation techniques have been proposed - quadrupole stabilization and positioning, final doublet stabilization as well as beam based orbit and interaction point (IP) feedback. Integrated studies of the impact of ground motion on the CLIC Main Linac (ML) and Beam Delivery System (BDS) that model the latest hardware designs have been performed. Furthermore, additional imperfections have been introduced and the robustness of this system is discussed in detail. The possibility of using ground motion measurements as an alternative to the quadrupole stabilization is investigated.  
 
TUPPR047 Vibration Model Validation for Linear Collider Detector Platforms simulation, damping, ground-motion, coupling 1921
 
  • K.J. Bertsche, J.W. Amann, T.W. Markiewicz, M. Oriunno, A.W. Weidemann, G.R. White
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
The ILC and CLIC reference designs incorporate reinforced-concrete platforms underneath the detectors so that the two detectors can each be moved onto and off of the beamline in a Push-Pull configuration. These platforms could potentially amplify ground vibrations which would reduce luminosity. In this paper we compare vibration models to experimental data on reinforced concrete structures, estimate the impact on luminosity, and summarize implications for the design of a reinforced concrete platform for the ILC or CLIC detectors. 		 
 
TUPPR052 3D FEA Computation of the CLIC Machine Detector Interface Magnets solenoid, simulation, quadrupole, shielding 1936
 
  • A. Bartalesi, M. Modena
    CERN, Geneva, Switzerland
  
  A critical aspect of the Compact Linear Collider (CLIC) design is represented by the Accelerator/Experiment interface (called Machine Detector Interface or MDI). In the 3 TeV CLIC layout, the final focus QD0 quadrupole will be located inside the end-cap of the detector itself. This complex MDI scenario required to be simulated with a full 3D-FE analysis. This study was critical to check and control the magnetic cross-talk between the Detector Solenoid and the final Focus QD0 magnet and therefore to optimize the design of an “antisolenoids” system needed to shield the QD0 and the e−/e+ beams from the detector magnetic field. In this paper the development and evolution of the computational FE model is presented together with the results obtained and their implication on the CLIC MDI Design.  
 
TUPPR078 LEP3: A High Luminosity e+e− Collider in the LHC Tunnel to Study the Higgs Boson collider, positron, emittance, synchrotron 2005
 
  • F. Zimmermann, M. Koratzinos
    CERN, Geneva, Switzerland
  • A.P. Blondel
    DPNC, Genève, Switzerland
  • M. Zanetti
    MIT, Cambridge, Massachusetts, USA
  
  Recent indications from two LHC experiments suggest that the Higgs boson might be light, within the mass range 115-130 GeV. Such object could be studied at an e+e− collider with about 240 GeV centre-of-mass energy. A corresponding Higgs factory – “LEP3” - could be installed in the LHC tunnel, reducing its cost and also allowing for a second life of the two LHC general-purpose detectors. We present preliminary accelerator and beam parameters for LEP3 tailored so as to provide a peak luminosity of 1034/cm2/s at each of two experiments, while respecting a number of constraints including beamstrahlung limits. At this luminosity around 20,000 Higgs events per year per experiment could be obtained for a Standard Model Higgs boson with a mass of 115-130 GeV. For the parameters considered the estimated luminosity lifetime is about 12 minutes, and the synchrotron radiation losses are 50 MW per beam. High operational efficiency requires two rings: a low emittance collider storage ring operating at constant energy, and a separate accelerator to top up the colliding beams every few minutes. The alternative of a larger ring collider installed in a new, bigger tunnel will also be discussed.  
 
TUPPR094 SPS Transverse Beam Scraping and LHC Injection Losses injection, emittance, proton, controls 2050
 
  • L.N. Drosdal, W. Bartmann, C. Bracco, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, E. Veyrunes
    CERN, Geneva, Switzerland
  
  Machine protection sets strict requirements for the quality of the injected beam, in particular in the transverse plane. Losses at aperture restrictions and protection elements have to be kept at a minimum. Particles in the beam tails are lost at the tight transfer line collimators and can trigger the LHC beam abort system. These particles have to be removed by scrapers in the vertical and horizontal plane in the SPS. Scraping has become vital for high intensity LHC operation. This paper shows the dependence of injection quality on the SPS scraping and discusses an improved scraper setting up strategy for better reproducibility with the current scraper system.  
 
WEYA01 CLIC Status and Outlook linac, target, emittance, alignment 2076
 
  • S. Stapnes
    CERN, Geneva, Switzerland
  
  The Compact Linear Collider study (CLIC) is in the process of completing a Conceptual Design Report for a multi-TeV linear electron-positron collider. The CLIC-concept is based on high gradient normal-conducting accelerating structures. The RF power for the acceleration of the colliding beams is produced by a novel two beam acceleration scheme, where power is extracted from a high current drive beam that runs parallel with the main linac. In order to establish the feasibility of this concept a number of key issues have been addressed. A short summary of the progress and status of the corresponding studies will be given, as well as an outline of the preparation and work towards an implementation plan by 2016.  
slides icon Slides WEYA01 [11.960 MB]  
 
WEOBA02 Tevatron End-of-Run Beam Physics Experiments antiproton, proton, emittance, dipole 2128
 
  • A. Valishev
    Fermilab, Batavia, USA
  • X. Gu, R. Miyamoto, S.M. White
    BNL, Upton, Long Island, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  • F. Schmidt
    CERN, Geneva, Switzerland
  
  Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP).
Before the Tevatron collider Run II ended in September of 2011, a two-week period was devoted to the experiments on various aspects of beam-beam interactions. The studied topics included offset collisions, coherent beam stability, effect of the bunch-length-to-beta-function ratio, and operation of AC dipole with colliding beams. In this report we summarize the results of beam experiments and supporting simulations. 		 
slides icon Slides WEOBA02 [1.382 MB]  
 
WEPPC032 Analysis of the Four Rod Crab Cavity for HL-LHC cavity, multipactoring, simulation, niobium 2275
 
  • B.D.S. Hall, P.K. Ambattu, G. Burt, D. Doherty, C. Lingwood
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P. Goudket
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  The Hi-Lumi Upgrade to the LHC will utilise crab cavities to increase the peak luminosity and provide luminosity levelling at the increased crossing angle. A transversely compact design is required to fit within the limited space between opposing beamlines. In this paper a four rod TEM deflecting cavity (4RCC) is shown to be suitable for LHC. The variation of the deflecting voltage with radial offset has been minimised by careful design and an aluminium prototype has been constructed and beadpull measurements are compared to simulations. Multipacting simulations have been performed on the cavity geometry and it is predicted that the growth rate is less than unity for a clean surface. Pressure variations in the LHe can result in deformation of the complex shape which will alter the resonant frequency. Mechanical simulations have also been performed to assess the sensitivity of the frequency to pressure. In order to reduce the impact of these cavities on the LHC beam low impedance is required for the HOMs as well as the fundamental monopole mode. The couplers for the 4RCC cavity have been optimised to provide effective damping of these modes while rejecting the operating mode.  
 
WEPPC085 Engineering of a Superconducting 400 MHz Crabbing Cavity for the LHC HiLumi Upgrade cavity, niobium, collider, SRF 2411
 
  • D. Gorelov, T.L. Grimm
    Niowave, Inc., Lansing, Michigan, USA
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  
  Funding: This work is supported by the US DOE-HEP SBIR/STTR program and the US DOE through the US LHC Accelerator Research Program (LARP).
The recently developed new simplified design for the 400 MHz LHC crabbing cavity presents attractive properties compared to conventional designs. The proposed approach can be equally compact in both transverse dimensions and allows horizontal as well as vertical deflection of the beam in the collider. The significant modification of the parallel-bar design with the bars merged to the side walls of the cavity gives improved properties, such as better mode separation and reduced surface fields*. A transverse deflecting voltage of 3 to 5 MV in a single cavity can be expected with the peak surface electric field lower then 50 MV/m and peak magnetic field below 100 mT. This paper presents engineering issues of the proof-of-concept crabbing cavity design and discusses the manufacturing techniques. The paper discusses present status of the project including fabrication of the niobium cavity, as well as room temperature and cryogenic testing.
* J.R. Delayen, S.U. De Silva, "Design of Superconducting Parallel-Bar Deflecting/Crabbing Cavities with Improved Properties," Proc. of 2011 PAC, New York, NY, USA, 2011, p. 1021. 		 
 
WEPPC102 Design and Development of Superconducting Parallel-bar Deflecting/Crabbing Cavities cavity, HOM, pick-up, damping 2453
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • S.U. De Silva
    JLAB, Newport News, Virginia, USA
  
  The superconducting parallel-bar cavity is a deflecting/crabbing cavity with attractive properties that is being considered for a number of applications. We present the designs of a 499 MHz deflecting cavity developed for the Jefferson Lab 12 GeV Upgrade and a 400 MHz crabbing cavity for the LHC High Luminosity Upgrade. Prototypes of these two cavities are now under development and fabrication.  
 
WEPPD056 Ytterbium Fiber Laser System of DAW RF Gun for SuperKEKB laser, emittance, gun, cavity 2648
 
  • X. Zhou, T. Natsui, Y. Ogawa, M. Yoshida
    KEK, Ibaraki, Japan
  
  For obtaining higher luminosity in the SuperKEKB, the photocathode DAW-type RF gun for high-current, low-emittance beams will be employed in the injector linac. The electron beams with a charge of 5 nC and a normalized emittance of 10 micrometer are expected generate in the photocathode RF gun by using the laser source with a center wavelength of 260 nm and a pulse width of 30 ps. Fiber laser especially Ytterbium(Yb) fiber have attracted attention as one of the promising practical alternatives to usual solid-state lasers, offering high energy-extraction efficiency, high repetition rate, high output power, low-cost and so on. Introducing the Ytterbium fiber laser system, we have developed a stable laser amplifier system, which could allow steady beam injection into the SuperKEKB rings. The laser system starts with a large mode-area Yb-doped fiber-based amplifier system, which consists of a passively mode-locked femtosecond Yb-fiber oscillator. To obtain the mJ-class pulse energy, a multi-pass solid-state amplifier is employed. Deep UV pulses for the photocathode are generated by using two frequency-doubling stages. High pulse energy and good stability would be expected.  
 
WEPPP082 Stochastic Cooling in RHIC kicker, emittance, pick-up, simulation 2900
 
  • J.M. Brennan, M. Blaskiewicz, K. Mernick
    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.
Stochastic cooling is used in the Relativistic Heavy Ion Collider to increase the integrated luminosity of ion collisions by a factor of two. The cooling system has been assembled incrementally over the past several years, starting with longitudinal cooling only, then adding cooling in the vertical planes, and recently completed with cooling systems in all three phase space planes of both rings. The system operates from 6 to 9 GHz in the longitudinal planes and from 4.7 to 7.8 GHz in the transverse planes, yielding a cooling rate that overcomes Intra-Beam Scattering at the beginning of a store and reaches equilibrium with a factor of 2 reduction of emittances. The system’s components and mode of operation will be presented along with measurements of the beam parameters during stores with stochastic cooling in operation. 		 
 
WEPPR004 Effect of Beam-beam Interactions on Stability of Coherent Oscillations in a Muon Collider collider, resonance, lattice, quadrupole 2940
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  • Y. Alexahin
    Fermilab, Batavia, USA
  
  In order to achieve the peak luminosity of a muon collider in the 1035 cm-2 s-1 range the number of muons per bunch should be of the order of a few units of 1012 rendering the beam-beam parameter as high as 0.1 per IP. Such strong beam-beam interaction can be a source of instability if the working point is chosen close to a coherent beam-beam resonance. On the other hand, the beam-beam tune spread can provide a mechanism of suppression of the beam-wall driven instabilities. In this report the coherent instabilities driven by beam-beam and beam-wall interactions are studied with the help of BBSS code for the case of 1.5 TeV c.o.m muon collider.  
 
WEPPR016 Potential for Luminosity Improvement for Low-energy RHIC Operation space-charge, electron, ion, emittance 2973
 
  • A.V. Fedotov
    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.
At the Brookhaven National Laboratory, a physics program, motivated by the search of the QCD phase transition critical point, requires operation of the Relativistic Heavy Ion Collider (RHIC) with heavy ions at very low beam energies corresponding to 2.5-20 GeV/n. Several physics runs were already successfully performed at these low energies. However, the luminosity is very low at lowest energies of interest (< 10 GeV/n) limited by the intra-beam scattering and space-charge, as well as by machine nonlinearities. At these low energies, electron cooling is very effective in counteracting luminosity degradation due to the IBS, while it is less effective against other limitations. Overall potential luminosity improvement for low-energy RHIC operation from cooling is summarized for various energies, taking into account all these limitations as well as beam lifetime measured during the low-energy RHIC runs. We also explore a possibility of further luminosity improvement under the space-charge limitation. 		 
 
WEPPR066 Effects of the External Wakefield from the CLIC PETS linac, wakefield, emittance, dipole 3078
 
  • A. Latina, D. Schulte
    CERN, Geneva, Switzerland
  • J. Gao, Y. Wang
    IHEP, Beijing, People's Republic of China
  
  The CLIC main linac accelerating structures will be powered by the Power Extraction and Transfer Structure (PETS) located in the drive beam decelerators. Misalignments of the PETS will excite dipolar modes in the couplers of the main linac structures that will kick the beam leading to beam quality degradation. In this paper, the impact of such dipolar kicks is studied, and tolerances, based on analytical estimations, are found both in the single- and the multi-bunch regimes. Numerical simulation obtained using the tracking code PLACET are shown to confirm the analytical estimates.  
 
THYA01 High Field Magnet Developments dipole, quadrupole, alignment, collider 3185
 
  • T. Nakamoto
    KEK, Ibaraki, Japan
  
  Superconducting magnets for future accelerators need to generate a field beyond 10 T. However, mature NbTi superconductors which have been already operated at its performance limit at LHC cannot be adopted. Instead, A15 type superconductors have been considered to be promising materials for the high field magnets. Especially, intensive R&D efforts for the LHC luminosity upgrade with state-of-the-art Nb3Sn superconductors have been carried out. Further future accelerators such as the High-Energy LHC and muon accelerators must require the high field reaching 20 T or more. This means that utilization of HTS (high Tc superconductors) would be the only possible solution. However, it is known that these advanced superconductors are not mechanically robust in comparison with the practical NbTi and the performance is influenced by mechanical stress and strain. In addition, magnetization effects caused by larger effective filament diameters may compromise the field quality in the accelerators. The magnet developments to overcome these issues are ongoing. This presentation will try to review the US and worldwide high field accelerator magnet developments: achievements, status, and plans.  
slides icon Slides THYA01 [7.578 MB]  
 
THYB01 Beam-beam Limit in a Hadron Collider emittance, simulation, resonance, collider 3208
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  
  Beam-beam limit phenomenon is observed in degradation of luminosity lifetime and/or beam life time in hadron colliders, especially in LHC. We focus the luminosity degradation in this paper. Various effects to degrade the luminosity grow severe in a high beam intensity. Coherent beam-beam instability, incoherent beam-beam emittance growth and those cupeled with lattice errors, external noises, intra-beam scattering. The beam-beam limit in an ideal machine and a machine with above errors is discussed with theory and simulation. Experimental results are reviewed and compare with the theory and simulations.  
slides icon Slides THYB01 [4.712 MB]  
 
THYB03 Collective Effects in the LHC and its Injector Complex emittance, linac, impedance, injection 3218
 
  • E. Métral
    CERN, Geneva, Switzerland
  
  Operation during 4-8 hours at a constant luminosity of five times the nominal one (with “leveling”) is required for the CERN HL-(High Luminosity)-LHC project to be able to reach integrated luminosities of ~ 250 fb-1 per year and ~ 3 ab-1 twelve years after the upgrade. This means that the potential peak luminosity should be at least two times larger than the leveled one, i.e. a factor more than ten compared to the nominal case is contemplated. Even though the LHC had a bold beginning, reaching one third of the nominal peak luminosity at the end of the 2011 run, a factor more than thirty remains to be gained, which will be achieved only if all the collective effects are deeply understood and mastered both in the LHC and its injectors. The observations made during the 2010-2011 runs are first reviewed and compared to predictions to try and identify possible bottlenecks. The lessons learned and the possible solutions and/or mitigation measures to implement in the HL-LHC and the LHC Injectors Upgrade (LIU) projects are then discussed.  
slides icon Slides THYB03 [34.295 MB]  
 
THPPD009 Accelerator Magnets R&D Programme at CERN dipole, quadrupole, permanent-magnet, linac 3512
 
  • D. Tommasini, L. Bottura, G. De Rijk, L. Rossi
    CERN, Geneva, Switzerland
  
  The exploitation and evolution of the CERN accelerator complex pose a continuous challenge for magnet engineers. Superconducting and resistive magnets have a comparable share. The overall mass of either is approximately 50,000 tons, spread over 3 major machines (PS, SPS and LHC), two large experimental area, and a number of smaller experiments and accelerator rings. On the short term (2012-2014) the CERN plan is to upgrade its injection chain (Linac4) and experimental area (HIE-Isolde, ELENA) that require mostly a multitude of resistive magnets. The medium-term plan for the evolution of the LHC complex (2015-2021), also referred to as High-Luminosity LHC, foresees interventions on about 1 km of the machine, with magnets to be substituted with higher field, larger aperture, or both. On the long term (2025-2035) we are exploring the technological challenges of very high field magnets, at the verge of 20 T for a High Energy LHC (HE-LHC), or extremely stable high gradient quadrupoles for the Compact Linear Collider (CLIC). In this paper we provide an overview of the R&D activities addressing the various lines of development, the technology milestones, and a broad time schedule.  
 
THPPD029 Machine Availability at the Large Hadron Collider cryogenics, controls, collider, hadron 3566
 
  • M. Pojer, R. Schmidt, M. Solfaroli Camillocci, S. Wagner
    CERN, Geneva, Switzerland
  
  One of the most important parameters for a particle accelerator is its uptime, the period of time when it is functioning and available for use. In its second year of operation, the Large Hadron Collider (LHC) has experienced very high machine availability, which is one of the ingredients of its brilliant performance. Some of the strategies followed to increase MTBF are described in the paper. The approach of periodic maintenance stops, often questioned, is also discussed. Some considerations on the ideal length of a physics fill are also drawn.  
 
THPPD035 Magnets for Interaction Regions of a 1.5×1.5 TeV Muon Collider dipole, quadrupole, collider, background 3584
 
  • V. Kashikhin, Y. Alexahin, N.V. Mokhov, A.V. Zlobin
    Fermilab, Batavia, USA
  
  Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
The updated IR optics and conceptual designs of large aperture superconducting quadrupole magnets for a muon collider with a c.o.m. energy of 3 TeV and an average luminosity of 4·1034 cm-2 s-1 are presented. All magnets are based on the Nb3Sn superconductor and designed to provide an adequate operation field gradient in the given aperture with the critical current margin required for reliable machine operation. Special dipole coils were added to quadrupole designs to provide ~2 T bending field and thus facilitate chromaticity correction and dilute decay electron fluxes on the detector. Magnet cross-sections were optimized to achieve the best possible field quality in the magnet aperture occupied with beams. Magnet parameters are reported and compared with the requirements. Energy deposition calculations with the MARS code have allowed to optimize parameters of inner absorbers, collimators in interconnect regions and Machine-Detector Interface. 		 
 
THPPD040 Quench Protection Analysis of a Single-Aperture 11T Nb3Sn Demonstrator Dipole for LHC Upgrades dipole, simulation, quadrupole, status 3599
 
  • A.V. Zlobin, I. Novitski, R. Yamada
    Fermilab, Batavia, USA
  
  Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
The planned upgrade of the LHC collimation system foresees additional collimators to be installed in the dispersion suppressor areas around points 2, 3, and 7. The necessary longitudinal space for the collimators could be provided by replacing some 8.33-T 15-m-long NbTi LHC main dipoles with shorter 11-T Nb3Sn dipoles compatible with the LHC lattice and main systems. To demonstrate this possibility, in 2011 Fermilab and CERN started a joint R&D program with the goal of building by 2014 a 5.5-m-long twin-aperture dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2-m-long single-aperture demonstration dipole with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and 60-mm bore with ~20% margin. This paper summarizes the results of quench protection analysis of the single-aperture Nb3Sn demonstrator dipole for the LHC collimation system upgrade. 		 
 
THPPD076 Evaluation of Components for the High Precision Inductive Adder for the CLIC Damping Rings damping, kicker, emittance, collider 3692
 
  • J. Holma, M.J. Barnes
    CERN, Geneva, Switzerland
  
  The CLIC study is exploring the scheme for an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC damping rings will produce, through synchrotron radiation, ultra-low emittance beam with high bunch charge, necessary for the luminosity performance of the collider. To limit the beam emittance blow-up due to oscillations, the pulse generators for the damping ring kickers must provide extremely flat, high-voltage pulses. The specifications for the extraction kickers of the CLIC damping rings are particularly demanding: the flattop of the output pulse must be 160 ns duration, 12.5 kV and 250 A, with a combined ripple and droop of not more than ±0.02 %. An inductive adder allows the use of different modulation techniques and is therefore a very promising approach to meeting the specifications. In addition to semiconductors working in their saturated region, semiconductors working in their linear region are needed for applying analogue modulation techniques. Simulations have been carried out to define component specifications for the inductive adder: this paper reports the results of tests and measurements of various components.  
 
THPPP006 Radiation Damage to Electronics at the LHC radiation, shielding, hadron, proton 3734
 
  • M. Brugger
    CERN, Geneva, Switzerland
  
  Control systems installed in LHC underground areas using COTS (Commercial Off The Shelf) components are all affected by the risk of ‘Single Event Effects.’ In the LHC tunnel, in addition, cumulative dose effects have also to be considered. While for the tunnel equipment certain radiation tolerant design criteria were already taken into account during the LHC construction phase, most of the equipment placed in adjacent and partly shielded areas was not conceived nor tested for their current radiation environment. Given the large amount of electronics being installed in these areas, a CERN wide project called R2E (Radiation To Electronics) has been initiated to quantify the risk of radiation-induced failures and to mitigate the risk for nominal beams and beyond to below one failure a week. This paper summarizes the analysis and mitigation approach chosen for the LHC, presents the encountered difficulties and the obtained experience in the following aspects: radiation fields & related calculations, monitoring and benchmarking; commercial equipment/systems and their use in the LHC radiation fields; radiation tests with dedicated test areas and facilities*.
* Work presented on behalf of the CERN ’Radiation to Electronics (R2E) Mitigation Project’ and the ‘Radiation Working Group (RadWG)’ 		 
 
THPPP010 LHC Orbit Correction Reproducibility and Related Machine Protection controls, feedback, status, injection 3746
 
  • K. Fuchsberger, T. Baer, R. Schmidt, J. Wenninger
    CERN, Geneva, Switzerland
  
  The Large Hadron Collider (LHC) has an unprecedented nominal stored beam energy of up to 362 MJ per beam. In order to ensure an adequate machine protection by the collimation system, a high reproducibility of the beam position at collimators and special elements like the final focus quadrupoles is essential. This is realized by a combination of manual orbit corrections, feed forward and real time feedback. In order to protect the LHC against inconsistent orbit corrections, which could put the machine in a vulnerable state, a novel software-based interlock system for orbit corrector currents was developed. In this paper, the principle of the new interlock system is described and the reproducibility of the LHC orbit correction is discussed against the background of this system.  
 
THPPP012 Performance of the CERN Heavy Ion Production Complex ion, target, injection, proton 3752
 
  • D. Manglunki, M. E. Angoletta, H. Bartosik, G. Bellodi, A. Blas, T. Bohl, C. Carli, E. Carlier, S. Cettour Cave, K. Cornelis, H. Damerau, I. Efthymiopoulos, A. Findlay, S.S. Gilardoni, S. Hancock, J.M. Jowett, D. Kuchler, S. Maury, M. O'Neil, Y. Papaphilippou, S. Pasinelli, R. Scrivens, G. Tranquille, B. Vandorpe, U. Wehrle, J. Wenninger
    CERN, Geneva, Switzerland
  
  The second LHC ion run took place at 1.38 A TeV/c per beam in autumn 2011; more than 100 inverse microbarns was accumulated by each of the experiments. In addition, the LHC injector chain delivered primary Pb and secondary Be ion beams to fixed target experiments in the North Area. This paper presents the current performance of the heavy ion production complex, and prospects to further improve it in the near future.  
 
THPPP018 Operation of the LHC at High Luminosity and High Stored Energy injection, vacuum, emittance, radiation 3767
 
  • J. Wenninger, R. Alemany-Fernandez, G. Arduini, R.W. Assmann, B.J. Holzer, E.B. Holzer, V. Kain, M. Lamont, A. Macpherson, G. Papotti, M. Pojer, L. Ponce, S. Redaelli, M. Solfaroli Camillocci, J.A. Uythoven, W. Venturini Delsolaro
    CERN, Geneva, Switzerland
  
  In 2011 the operation of the Large Hadron Collider LHC entered its first year of high luminosity production at a beam energy of 3.5 TeV. In the first months of 2011 the number of bunches was progressively increased to 1380, followed by a reduction of the transverse emittance, an increase of the bunch population and a reduction of the betatron function at the collision points. The performance improvements steps that were accumulated in 2011 eventually brought the peak luminosity to 3.6·1033 cm-2s−1. The integrated luminosity delivered to each of the high luminosity experiments amounted to 5.6 fb-1, a factor of 5 above the initial target defined in 2010. The operational experience with high intensity and high luminosity at the LHC will be presented here, together with the issues that had to be tackled on the road to high intensity and luminosity.  
 
THPPR036 Quench Limit Calculations for Steady State Heat Deposits in LHC Inner Triplet Magnets quadrupole, proton, insertion, simulation 4050
 
  • D. Bocian
    IFJ-PAN, Kraków, Poland
  • F. Cerutti, B. Dehning, A.P. Siemko
    CERN, Geneva, Switzerland
  
  In hadron colliders such as the LHC, the energy deposited in the superconductors by the particles lost from the beams or coming from the collision debris may provoke quenches detrimental to the accelerator operation. A Network Model is used to simulate the thermodynamic behavior of the superconducting magnets. In previous papers the validations of network model with measurements performed in the CERN and Fermilab magnet test facilities were presented. This model was subsequently used for thermal analysis of the current LHC inner triplet quadrupole magnets for beam energy of 3.5 TeV and 7 TeV. The detailed study of helium cooling channels efficiency for energy deposits simulated with FLUKA is presented. Some conclusions are drawn on expected inner triplet magnets quench limit.  
 
THPPR037 Estimation of Thresholds for the Signals of the BLMs around the LHC Final Focus Triplet Magnets proton, simulation, radiation, beam-losses 4053
 
  • M. Sapinski, F. Cerutti, B. Dehning, A. Ferrari, A. Lechner, M. Mauri, A. Mereghetti
    CERN, Geneva, Switzerland
  • C. Hoa
    CEA-CENG, Grenoble, France
  
  The Interaction Points of the Large Hadron Collider are the regions where the two circulating beams collide. Hence, the magnets the closest to any Interaction Point are exposed to an elevated radiation field due to the collision debris. In this study the signal in the Beam Loss Monitors due to the debris is estimated and compared with the measurements. In addition, the energy density in the coils and the signal in the Beam Loss Monitors at quench are estimated for various beam loss scenarios. It is shown that the Beam Loss Monitors, as presently installed on the outside of the vacuum vessel of the magnets, cannot disentangle the signals due to a localised halo loss from that of the constant signal due to the collision debris.  
 
THPPR040 First Operational Experience with the LHC Machine Protection System when Operating with Beam Energies Beyond the 100 MJ Range injection, monitoring, feedback, interlocks 4062
 
  • M. Zerlauth, R.W. Assmann, B. Dehning, M. Ferro-Luzzi, B. Goddard, M. Lamont, R. Schmidt, A.P. Siemko, J.A. Uythoven, J. Wenninger
    CERN, Geneva, Switzerland
  
  The LHC made a remarkable progress in luminosity production during 2011 operation. This was made possible by a progressive increase of beam intensities by more than 5 orders of magnitude, reaching stored beam energies beyond 100MJ at the end of the year. The correct functioning of the machine protection systems was vital during initial operation and even more when approaching nominal beam parameters, where an uncontrolled loss of a small fraction of the beam is already sufficient to damage accelerator equipment or the large experimental detectors The machine protection system depends on the interplay of many different elements: beam dumping system, beam interlocks, beam instrumentation, equipment monitoring, collimators and absorbers, etc. The strategy applied during 2011 to allow for an efficient but yet safe increase of the beam intensities is presented along with the associated risks and drawbacks of a too aggressive approach. The experience gained with the key systems will be discussed along with possibilities to further enhance machine availability whilst maintaining the current level of safety.  
 
FRYCP01 Physics Results at the LHC and Implications for Future HEP Programmes collider, proton, electron, linear-collider 4190
 
  • R. Heuer
    CERN, Geneva, Switzerland
  
  This presentation should review the accumulated data of the TEVATRON and the first two years of LHC operation, highlighting major results and findings for high energy physics. This talk should highlight the most burning questions in high energy physics that emerged in light of these new results and discuss their implication for the planning and preparation of future accelerator projects.  
slides icon Slides FRYCP01 [14.536 MB]