Summary
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Transcript of Summary
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apex bbtf 11Apr07
Preliminary results:Preliminary results:Beam-Beam Transfer Function Beam-Beam Transfer Function for Luminosity Optimization for Luminosity Optimization
P. Cameron, A. Drees, A. Dellapenna,…
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apex bbtf 11Apr07
SummarySummary• The approach at CESR
– Radiation damping means they can kick hard– Look off resonance
• The approach at RHIC – Excitation power is limited by emittance growth– Excite ‘on resonance’ to enhance the coupling
• Results– We observed anti-correlation between ZDC’s and BBTF!
• This is not understood, no obvious cause
– Higher excitation levels caused emittance growth– No plan to further pursue on-resonance excitation
• Future request– 2 hours in 2 weeks to study off-resonance excitation
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apex bbtf 11Apr07
CESR CESR systemsystem
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apex bbtf 11Apr07
The APEX procedure as The APEX procedure as originally conceivedoriginally conceived
• Take swept BBTF to find zero phase• Lock BBQ thru the continuous BBTF• Do vernier scan• Compare amplitude of BBTF and vernier scan results
• This can be done parasitically early in the run, to get preliminary results?
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apex bbtf 11Apr07
The APEX procedure as doneThe APEX procedure as done
• Concern with effects of phase shifts due to beam-beam corrupting the ‘tune-tracking’ approach
• Solution was– Excite beam in one ring with white noise – more robust, does not require locking BBQ to
beam– Do vernier scan– Record data with BTM DAQ for offline analysis– Initial offline analysis is spectral power within a specified tune window
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apex bbtf 11Apr07
blue beamyellow beam
Beam Transfer Function measure here excite here
Beam-Beam Transfer Function excite here measure here
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apex bbtf 11Apr07
Blue beam response to white noise excitation in yellow (both planes), as seen by the ‘back-up’ DAQ (turned out to be un-needed)
H
V
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apex bbtf 11Apr07
ZDC signals during the first two position scans
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apex bbtf 11Apr07
BPM signals during the first position scan
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apex bbtf 11Apr07
3D AFE signals during the first position scan
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apex bbtf 11Apr07
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apex bbtf 11Apr07
Integral of 3D AFE FFT in the tune window from .215 to .24 during the first position scan
BTF – yellow excitation
BBTF – blue responseBBTF – blue response
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apex bbtf 11Apr07
BBTF – blue vert response
BBTF – blue horizresponse
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apex bbtf 11Apr07
The vernier scan app for the first position scan
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apex bbtf 11Apr07
1st scan 2nd scan
forgot to turn kicker off
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apex bbtf 11Apr07
1st scan 2nd scan
IPM
Schottky
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apex bbtf 11Apr07
1st scan
2nd scan
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apex bbtf 11Apr07
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apex bbtf 11Apr07
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apex bbtf 11Apr07
SummarySummary• The approach at CESR
– Radiation damping means they can kick hard– Look off resonance
• The approach at RHIC – Excitation power is limited by emittance growth– Excite ‘on resonance’ to enhance the coupling
• Results– We observed anti-correlation between ZDC’s and BBTF!
• This is not understood, no obvious cause
– Higher excitation levels caused emittance growth– No plan to further pursue on-resonance excitation
• Future request– 2 hours in 2 weeks to study off-resonance excitation