Machine Studies and Instrumentation in High Energy Particle Collider
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December/January operations focus on luminosity enhancement, orbit stability, beam monitoring, and simulation. Addressing tilt, tune spread, and monitoring vital for performance optimization.
Machine Studies and Instrumentation in High Energy Particle Collider
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CESR-c Status • -Operations/Luminosity • December/January vs September/October • Machine studies and instrumentation • Simulation and modeling D. Rubin - Cornell
Peak Luminosity D. Rubin - Cornell
Specific Luminosity D. Rubin - Cornell
Integrated Luminosity D. Rubin - Cornell
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 D. Rubin - Cornell
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 D. Rubin - Cornell
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 D. Rubin - Cornell
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 D. Rubin - Cornell
Machine Studies/Instrumentation • 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 D. Rubin - Cornell
SCMATING 2 = -160 D. Rubin - Cornell
SCMATING 2 = -120 D. Rubin - Cornell
SCMATING 2 = -70 D. Rubin - Cornell
SCMATING 2 = -40 D. Rubin - Cornell
SCMATING 2 = -120 D. Rubin - Cornell
SCMATING 2 = -70 D. Rubin - Cornell
SCMATING 2 = -40 D. Rubin - Cornell
SCMATING 2 = 70 D. Rubin - Cornell
SCMATING 2 = 40 D. Rubin - Cornell
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 D. Rubin - Cornell
Beam beam simulation 1.89 GeV/beam D. Rubin - Cornell
Simulation -Real wigglers, -Linearized wigglers, -Pretzel off/real wigglers No significant difference In low current behavior D. Rubin - Cornell
Machine Studies/Instrumentation (cont) • 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 D. Rubin - Cornell
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 D. Rubin - Cornell