Author: White, S.M.
Paper Title Page
MOPPC026 Simulations of Coherent Beam-Beam Effects with Head-on Compensation 187
 
  • S.M. White, W. Fischer, Y. Luo
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work partially supported by Brookhaven Science Associates, LARP, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron lenses are foreseen to be installed in RHIC in order to mitigate the head-on beam-beam effects. This would allow operation with higher bunch intensity and result in a significant increase in luminosity. We report on recent strong-strong simulations that were carried out using the RHIC upgrade parameters to assess the impact of coherent beam-beam effects in the presence of head-on compensation.
 
 
MOPPC027 Synchro-Betatron Effects in the Presence of Large Piwinski Angle and Crab Cavities at the HL-LHC 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.
 
 
MOPPC028 Coherent Beam-Beam Effects Observation and Mitigation at the RHIC Collider 193
 
  • S.M. White, M. Bai, W. Fischer, Y. Luo, A. Marusic, M.G. Minty
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work partially supported by Brookhaven Science Associates, LARP, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In polarized proton operation in RHIC coherent beam-beam modes are routinely observed with beam transfer function measurements in the vertical plane. With the existence of coherent modes a larger space is required in the tune diagram than without them and stable conditions can be compromised for operation with high intensity beams as foreseen for future luminosity upgrades. We report on experiments and simulations carried out to understand the existence of coherent modes in the vertical plane and their absence in the horizontal plane, and investigate possible mitigation strategies.
 
 
MOPPC029 Off-momentum Beat-beat Correction in the RHIC Proton Run 196
 
  • Y. Luo, M. Bai, W. Fischer, A. Marusic, K. Mernick, 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 this article we will present the measurement and correction of the off-momentum β*-beat in the RHIC proton run. The beta-beat will be measured with the AC dipole and by shifting RF frequency. We will focus on the correction of the off-momentum beta-beat at the interaction points IP6 and IP8 with the arc chromatic sextupole families. The effects of the off-momentum beta-beat correction on the global chromaticities and dynamic aperture will be estimated through beam experiments and the numerical simulation.
 
 
MOPPR076 Using the BRAN Luminosity Detectors for Beam Emittance Monitoring During LHC Physics Runs 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.
 
 
TUPPC056 Optics Measurements and Corrections at RHIC 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 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.
 
 
WEOBA02 Tevatron End-of-Run Beam Physics Experiments 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]  
 
WEOBA01 Construction Progress of the RHIC Electron Lenses 2125
 
  • W. Fischer, Z. Altinbas, M. Anerella, E.N. Beebe, M. Blaskiewicz, D. Bruno, W.C. Dawson, D.M. Gassner, X. Gu, R.C. Gupta, K. Hamdi, J. Hock, L.T. Hoff, A.K. Jain, R.F. Lambiase, Y. Luo, M. Mapes, A. Marone, T.A. Miller, M.G. Minty, C. Montag, M. Okamura, A.I. Pikin, S.R. Plate, D. Raparia, Y. Tan, C. Theisen, P. Thieberger, J.E. Tuozzolo, P. Wanderer, S.M. White, W. Zhang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
In polarized proton operation, the RHIC performance is limited by the head-on beam-beam effect. To overcome these limitations two electron lenses are under construction. We give an overview of the progress over the last year. Guns, collectors and the warm electron beam transport solenoids with their associated power supplies have been constructed. The superconducting solenoids that guide the electron beam during the interaction with the proton beam are near completion. A test stand has been set up to verify the performance of gun, collector and some of the instrumentation. The RHIC infrastructure is being prepared for installation, and simulations continue to optimize the performance.
 
slides icon Slides WEOBA01 [7.672 MB]