CESR-c Status

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CESR-c Status. CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation Instrumentation Ongoing studies Projections. CESR-c. Energy reach 1.5-6GeV/beam - PowerPoint PPT Presentation

Transcript of CESR-c Status

  • CESR-c StatusCESR Layout - Pretzel, Wigglers, solenoid compensationPerformance to dateDesign parametersOur understanding of shortfallPlans for remediationInstrumentationOngoing studiesProjections

  • CESR-cEnergy reach 1.5-6GeV/beam

    Electrostatically separated electron-positron orbits accomodate counterrotating trains

    Electrons and positrons collide with ~3.5 mrad horizontal crossing angle

    9 5-bunch trains in each beam(768m circumference)

  • 12 superconducting wigglers 1.4 T < Bpeak < 2.1 T - Reduce radiation damping time from 500ms to 50ms at 1.9GeV beam energy Injection rate damping rate Instability thresholds damping rate Increased beambeam limit, tolerance to long range beam-beam effects - Increase emittance from 30nm to ~100-200nm

  • CESR-c Energy dependence Damping and emittance control with wigglers

  • 7-pole, 1.3m 40cm period, 161A, B=2.1TSuperconducting wiggler prototype installed fall 2002

  • Solenoid compensation schemePM, Q1, Q2 are rotated 4.5 degrees about axis, designed to compensate 1.5T solenoid at 5.3 GeVSkew quad coils are superimposed on Q1 and Q2 for fine tuneing and energy reachSkew quad 3, is third component in 3-pair compensation schemeThe first bending magnet is immediately beyond skew quad 3Q2Q1PMCLEO solenoidSkew quad 3 sk_q03wsk_q03e

  • Wiggler Beam MeasurementsInjection1 sc wiggler (and 2 pm CHESS wigglers) -> 8mA/min6 sc wiggler -> 50mA/min1/ = 4.5 s-11/ = 10.9s-1

  • Wiggler Beam Measurements 6 wiggler latticeInjection30 Hz 68mA/80sec60 Hz 67ma/50sec

  • Wiggler Beam MeasurementsSingle beam stability1/ = 4.5 s-11/ = 10.9s-12pm + 1 sc wigglers6 sc wigglers

  • D303.2004, 8X5, *=12mmPerformance

  • D303.2004Performance

  • PerformanceIntegrated from startOf cesrcIntegrated/dayIncluding best day

  • CESR-c design parameters

  • CESR-c Energy dependence In a wiggler dominated ring

    1/ ~ Bw2Lw ~ Bw LwE/E ~ (Bw)1/2 nearly independent of length (Bw limited by tolerable energy spread)Then 18m of 2.1T wiggler -> ~ 50ms -> 100nm-rad <

  • Bunch current2mA/bunch vs 4mA/bunch Limited by parasitic interactions (Single bunch current limit > 4mA) Our scaling from 5.3GeV beam energy neglected contribution to beam size from energy spread and high field wigglers => large energy spread

    Beam current 8X5 vs 9X5 (ion effects)

    Beam beam tune shift parameter Large energy spread, energy dependence of solenoid compensation dilutes beam size at low current Large energy spread, small * => high synchrotron tune, synchrobetatron resonances limit tune shift at high currentPerformance vs design

  • Weak strong beambeam simulationComparison with measurementsIn simulation, tune scan yields operating pointData: Assume all bunches have equal current and contribute equal luminosity

    CESR-c1.89 GeV, 12 2.1T wigglersPhase III IR

  • Weak strong beambeam simulationComparison with measurementsIn simulation, tune scan yields operating pointData: Assume all bunches have equal current and contribute equal luminosity

    CESR-c1.89 GeV, 12 2.1T wigglersPhase III IR5.3GeVPhase II IR

  • Weak strong beambeam simulation

    Lifetime Loss of 1 of 5000 particles in 100 k turns => 20 minute lifetimeCESR-c 9X5CESR-c 9X4Measure lifetime limited current ~ 2.2mA/bunch(9X5), ~2.6mA/bunch(9X4)

  • Q2Q1PMCLEO solenoidCompensating solenoidSkew quad

  • Anti-solenoid in IR

  • ++pQx+qQy+rQz=n|p|+|q|+|r| 3Qz=0.05

    Qz=0.1

  • pQx+qQy+rQz=n|p|+|q|+|r| 4++Qz=0.05Qz=0.01

  • Longitudinal emittance12 wigglers, 1.89GeV/beamE/E ~ 0.084%, ~ 50 ms, h = 120nmp = 0.0113v* = 12mmThen l = 12mm => Qs= 0.089

    Element M inserted in ring opposite IPThen l = 12mm => Qs= 0.049 or Qs =0.089 => l = 7.3mm

  • Longitudinal emittanceReduced momentum compaction and no solenoid

  • Luminosity projection

  • InstrumentationTurn by turn position at IPFast luminosity monitor Bunch by bunch luminosityBunch by bunch position/beam sizeStreak camera

  • Palmer

  • (magnification ~ 3.6)Palmer

  • Ongoing studyNonlinearitiesOptical distortion due to parasitic crossingsResonance remediationLow momentum compaction optics