February 5, 2005D. Rubin - Cornell1 CESR-c Status -Operations/Luminosity -Machine studies -Simulation and modeling -4.1GeV

February 5, 2005D. Rubin - Cornell2 Peak Luminosity

February 5, 2005D. Rubin - Cornell3 Specific Luminosity

February 5, 2005D. Rubin - Cornell4 Integrated Luminosity

February 5, 2005D. Rubin - Cornell5 Lost time

February 5, 2005D. Rubin - Cornell6 Machine Studies/Instrumentation Longitudinal instability Recent measurement indicates threshold at 5.1mA (feedback off) vs 35mA in September ? -> RF, tuning angle, phase noise? Streak camera shows train to train motion Stability is recovered with feedback to >100mA IR BPM turn by turn => coupling at IP part of standard characterization

February 5, 2005D. Rubin - Cornell7

February 5, 2005D. Rubin - Cornell8 Machine Studies/Instrumentation Flat route - Develop systematic method for optimizing conditions - Measure and correct orbit, phase, coupling, differential coupling, sextupole resonances - IR turn by turn measurements give pretzel off coupling of a single beam at the IP - corrected with skew quads - and electron/positron coupling with pretzel on - corrected with skew sextupoles With the installation of additional skew sextupoles correction of differential coupling has been automated.

February 5, 2005D. Rubin - Cornell9 Machine Studies/Instrumentation 10 wiggler optics - In 12 wiggler optics most of emittance generated in single wiggler at 15 - Flexibility of optics design constrain by low emittance requirement - Turning off wiggler at 15E/W yields optics with more efficient pretzel separation Compensation of parasitic interactions -Long range interactions distort beta of counterrotating beams. -Current dependent quadrupole corrections preserve zero current optical functions -Develop technique for measuring beta of electron bunch with 8X5 bunches of positrons

February 5, 2005D. Rubin - Cornell10 Machine Studies/Instrumentation Luminosity monitor Optimizers Separator nonlinearities/pretzel tonality Monitoring of differential vertical positions and sources of instability

February 5, 2005D. Rubin - Cornell11 Beam beam simulation Semi strong-strong simulation Machine model includes all individual guide field elements (RF, wigglers, separators,…) and nonlinearities radiation, damping, crossing angle, pretzel, parasitic interactions, … Weak beam ~ 200 macroparticles Track for 200,000 turns Use weak beam size to update strong beam -> Beams have equal charge and size Strong beam is fixed in space

February 5, 2005D. Rubin - Cornell12 Simulation plan Lattice with distributed radiation excitation Solenoid off optics 10 wiggler optics Dependence differential offset/angle at IP coupling/ differential coupling sextupoles/chromaticity tune spread

February 5, 2005D. Rubin - Cornell13 -Real wigglers, -Linearized wigglers, -Pretzel off/real wigglers No significant difference In low current behavior Simulation

February 5, 2005D. Rubin - Cornell14 Energy dependence of solenoid compensation - Phase space, dynamic aperture, tune scan - Chromaticity of coupling parameters - Characteristic of SC IR - Enhanced sensitivity due to bigger energy spread - Beam beam simulation Very preliminary

February 5, 2005D. Rubin - Cornell GeV Energy dependence  =  1/3 where  is the radiation damping rate Maximum current limited by  x. I max ~ E  x

February 5, 2005D. Rubin - Cornell GeV In a machine without fixed field wigglers  ~ E 2 => I max ~ E 3  ~ E 3 =>  ~ E so L ~ E 5

February 5, 2005D. Rubin - Cornell GeV In CESR-c Wiggler field at higher energy, limited by energy spread  ~ B w 2 E  ~ B w E, but limited by physical aperture and parasitic crossings  E /E ~ (B w E) 1/2 => B w ~1/E so L ~ E 5/3 => 15% more luminosity at 2.05 vs 1.89 GeV

February 5, 2005D. Rubin - Cornell18