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CESR-c Status

-Operations/Luminosity December/January vs September/October

-Machine studies and instrumentation

-Simulation and modeling

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Peak Luminosity

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Specific Luminosity

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Integrated Luminosity

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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

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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

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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

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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

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•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

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SCMATING 2 = -160

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SCMATING 2 = -120

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SCMATING 2 = -70

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SCMATING 2 = -40

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SCMATING 2 = -120

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SCMATING 2 = -70

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SCMATING 2 = -40

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SCMATING 2 = 70

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SCMATING 2 = 40

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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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-Real wigglers,-Linearized wigglers,-Pretzel off/real wigglers

No significant differenceIn low current behavior

Simulation

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•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)

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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

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