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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 Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

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Page 1: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

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

Page 2: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

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)

Page 3: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

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

Page 4: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

CESR-c Energy dependence

Damping and emittance control with wigglers

Page 5: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

7-pole, 1.3m 40cm period, 161A, B=2.1T

Superconducting wiggler prototype installed fall 2002

Page 6: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Solenoid compensation scheme

• PM, Q1, Q2 are rotated 4.5 degrees about axis, designed to compensate 1.5T solenoid at 5.3 GeV• Skew quad coils are superimposed on Q1 and Q2 for fine tuneing and energy

reach• Skew quad 3, is third component in “3-pair” compensation scheme• The first bending magnet is immediately beyond skew quad 3

Q2 Q1PM

CLEO solenoid

Skew quad 3 sk_q03w

sk_q03e

Page 7: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Wiggler Beam Measurements

-Injection

1 sc wiggler (and 2 pm CHESS wigglers) -> 8mA/min

6 sc wiggler -> 50mA/min

1/ = 4.5 s-1

1/ = 10.9s-1

Page 8: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Wiggler Beam Measurements 6 wiggler lattice

-Injection

30 Hz 68mA/80sec 60 Hz 67ma/50sec

Page 9: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Wiggler Beam Measurements

-Single beam stability

1/ = 4.5 s-1 1/ = 10.9s-1

2pm + 1 sc wigglers 6 sc wigglers

Page 10: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

D303.2004, 8X5, *=12mm

Performance

Page 11: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

D303.2004

Performance

Page 12: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Performance

Integrated from startOf cesrc

Integrated/dayIncluding best day

Page 13: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

CESR-c design parameters

Page 14: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

CESR-c Energy dependence In a wiggler dominated ring

• 1/ ~ Bw2Lw

~ Bw Lw

E/E ~ (Bw)1/2 nearly independent of length (Bw limited by tolerable energy spread)Then 18m of 2.1T wiggler -> ~ 50ms -> 100nm-rad < <300nm-rad

Page 15: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

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 current

Performance vs design

Page 16: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Weak strong beambeam simulation

• Comparison with measurements• In simulation, tune scan yields operating point• Data: Assume all bunches have equal current and contribute equal luminosity

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

Page 17: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Weak strong beambeam simulation• Comparison with measurements

• In simulation, tune scan yields operating point• Data: Assume all bunches have equal current and contribute equal luminosity

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

5.3GeVPhase II IR

Page 18: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Weak strong beambeam simulation

– Lifetime

1

τ=

1

N

dN

dt=

1

N

ΔN

nturns

f rev

Loss of 1 of 5000 particles in 100 k turns => 20 minute lifetime

CESR-c 9X5 CESR-c 9X4

Measure lifetime limited current ~ 2.2mA/bunch(9X5), ~2.6mA/bunch(9X4)

Page 19: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Q2 Q1PM

CLEO solenoid

Compensating solenoid

Skew quad

Page 20: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Anti-solenoid in IR

Page 21: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation
Page 22: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

+

+

pQx+qQy+rQz=n|p|+|q|+|r| ≤3

Qz=0.05

Qz=0.1

Page 23: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

pQx+qQy+rQz=n|p|+|q|+|r| ≤4

+

+

Qz=0.05

Qz=0.01

Page 24: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Longitudinal emittance• 12 wigglers, 1.89GeV/beam

E/E ~ 0.084%, ~ 50 ms, h = 120nm p = 0.0113 v

* = 12mm– Then l = 12mm => Qs= 0.089

• Element M inserted in ring opposite IP– Then l = 12mm => Qs= 0.049 or Qs =0.089 => l = 7.3mm

Page 25: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Longitudinal emittance• Reduced momentum compaction and no solenoid

Page 26: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation
Page 27: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Luminosity projection

Page 28: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Instrumentation

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

Page 29: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Palmer

Page 30: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

(magnification ~ 3.6)Palmer

Page 31: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation
Page 32: CESR-c Status CESR Layout - Pretzel, Wigglers, solenoid compensation Performance to date Design parameters Our understanding of shortfall Plans for remediation

Ongoing study

NonlinearitiesOptical distortion due to parasitic crossingsResonance remediationLow momentum compaction optics