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 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 < B peak < 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 ~ nm

CESR-c Energy dependence Damping and emittance control with wigglers

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

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 Q2Q1 PM CLEO solenoid Skew quad 3 sk_q03w sk_q03e

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

Wiggler Beam Measurements 6 wiggler lattice -Injection 30 Hz 68mA/80sec60 Hz 67ma/50sec

Wiggler Beam Measurements -Single beam stability 1/  = 4.5 s -1 1/  = 10.9s -1 2pm + 1 sc wigglers 6 sc wigglers

D , 8X5,  * =12mm Performance

D Performance

Integrated from start Of cesrc Integrated/day Including best day

CESR-c design parameters

CESR-c Energy dependence In a wiggler dominated ring 1/  ~ B w 2 L w  ~ B w L w  E /E ~ (B w ) 1/2 nearly independent of length (B w limited by tolerable energy spread) Then 18m of 2.1T wiggler ->  ~ 50ms -> 100nm-rad <  <300nm-rad

Bunch current 2mA/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

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-c 1.89 GeV, T wigglers Phase III IR

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-c 1.89 GeV, T wigglers Phase III IR 5.3GeV Phase II IR

Weak strong beambeam simulation –Lifetime Loss of 1 of 5000 particles in 100 k turns => 20 minute lifetime CESR-c 9X5CESR-c 9X4 Measure lifetime limited current ~ 2.2mA/bunch(9X5), ~2.6mA/bunch(9X4)

Q2Q1 PM CLEO solenoid Compensating solenoid Skew quad

Anti-solenoid in IR

+ + pQ x +qQ y +rQ z =n |p|+|q|+|r| ≤3 Q z =0.05 Q z =0.1

pQ x +qQ y +rQ z =n |p|+|q|+|r| ≤4 + + Q z =0.05 Q z =0.01

Longitudinal emittance 12 wigglers, 1.89GeV/beam –  E /E ~ 0.084%,  ~ 50 ms,  h = 120nm –  p = –  v * = 12mm –Then  l = 12mm => Q s = Element M inserted in ring opposite IP –Then  l = 12mm => Q s = or Q s =0.089 =>  l = 7.3mm

Longitudinal emittance Reduced momentum compaction and no solenoid

Luminosity projection

Instrumentation Turn by turn position at IP Fast luminosity monitor Bunch by bunch luminosity Bunch by bunch position/beam size Streak camera

Palmer

(magnification ~ 3.6) Palmer

Ongoing study Nonlinearities Optical distortion due to parasitic crossings Resonance remediation Low momentum compaction optics