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January 15, 2005 D. Rubin - Cornell 1
CESR-c Status
-Operations/Luminosity December/January vs September/October
-Machine studies and instrumentation
-Simulation and modeling
January 15, 2005 D. Rubin - Cornell 2
Peak Luminosity
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Specific Luminosity
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Integrated Luminosity
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January 15, 2005 D. Rubin - Cornell 6
January 15, 2005 D. Rubin - Cornell 7
Machine Studies/Instrumentation
•Horizontal separator tilt
Level measurements, tilt < 0.3 mrad, negligible effect on orbit But what about plate/vacuum can alignment ? Beam based measurement, tilt ~ 4 mrad
•Tune spread - Safe operating space in tune plane narrows with increasing current - Tune spread reduces current limit
- Instability in magnet power supply? - Modify feedback circuit for all quad choppers, no effect on tune spread
January 15, 2005 D. Rubin - Cornell 8
January 15, 2005 D. Rubin - Cornell 9
Machine Studies/Instrumentation
•Orbit stability Evidence of vertical orbit motion in - synchrotron radiation light monitor - orbit measurement with beam position monitors - turn by turn data at IR beam detectors - fast luminosity monitor Sources of vertical motion might include - Instability in quadrupole power supplies (Q48,49) - of vertical separator plate voltages - of skew quadrupole currents, SCIR skew quads
January 15, 2005 D. Rubin - Cornell 10
Machine Studies/Instrumentation
• Continuously monitor electron positron orbit difference - BPM electronics and software under development “true” differences with arbitrary time scales
- Better monitoring of suspect elements
January 15, 2005 D. Rubin - Cornell 11
Machine Studies/Instrumentation
• Luminosity monitor - Luminosity signal is compromised by lost particles when electron lifetime is poor - Detector segmentation provides means for correction DSP software begin developed - Plan to implement “true” calibration
- Software also in the works to enable bunch by bunch luminosity measurement
January 15, 2005 D. Rubin - Cornell 12
•Knobs to control differential coupling using skew sextupoles 3 new sextupoles installed
• Demonstrated capability to measure with turn by turn BPM data, coupling at IP - And “good” luminosity corresponds to measured flat beam at IP
• Developing IR BPM calibration and software to implement as part of coupling correction procedure
Machine Studies/Instrumentation
January 15, 2005 D. Rubin - Cornell 13
SCMATING 2 = -160
January 15, 2005 D. Rubin - Cornell 14
SCMATING 2 = -120
January 15, 2005 D. Rubin - Cornell 15
SCMATING 2 = -70
January 15, 2005 D. Rubin - Cornell 16
SCMATING 2 = -40
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SCMATING 2 = -120
January 15, 2005 D. Rubin - Cornell 18
SCMATING 2 = -70
January 15, 2005 D. Rubin - Cornell 19
SCMATING 2 = -40
January 15, 2005 D. Rubin - Cornell 20
SCMATING 2 = 70
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SCMATING 2 = 40
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January 15, 2005 D. Rubin - Cornell 23
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
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Beam beam simulation
1.89 GeV/beam
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January 15, 2005 D. Rubin - Cornell 26
-Real wigglers,-Linearized wigglers,-Pretzel off/real wigglers
No significant differenceIn low current behavior
Simulation
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January 15, 2005 D. Rubin - Cornell 28
•More bunches-10 bunches/train, 2 sets of 5 displaced by 2ns-Calculation of optical distortion due to parasitic additional interactions indicates small effect-Established injection of single 10 bunch train-Collisions of 2,3 electron bunches with 10 bunch positron train
• Alternatively 9 bunches/train 1 set 5 and 1 set 4 displaced 6ns under study
Machine Studies/Instrumentation (cont)
January 15, 2005 D. Rubin - Cornell 29
Simulation plan
•Lattice with distributed radiation excitation•Dependence
•differential offset/angle at IP•coupling/ differential coupling•sextupoles/chromaticity•tune spread
Thanks to CLEO collaborators Minnesota and Illinois and CHESS for making computers available and for help getting started
January 15, 2005 D. Rubin - Cornell 30