| Paper |
Title |
Page |
| THPLT150 |
Results from Orbit and Optics Improvement by Evaluating the Nonlinear Beam Position Monitor Response in CESR
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2804 |
| |
- R.W. Helms, G. Hoffstaetter
Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
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In the Cornell Electron/positron Storage Ring (CESR), pretzel orbits with large horizontal oscillations are used to keep electron and positron beams out of collision except at the interaction point. Since a beam position monitor's (BPM's) response is only linear near the center of the beam pipe, the assumption of linearity does not allow for accurate orbit and phase measurements under colliding beam conditions. Using a numerical model of the BPMs' response to large offsets of the beam position, and an enhanced algorithm for real-time inversion of this nonlinear response function, we have extended our orbit and betatron phase measurements to beams with large pretzel amplitudes. Several measurements demonstrate the applicability, accuracy, and usefulness of this method.
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| THPLT151 |
Evaluation of Beam Position Monitors in the Nonlinear Regime
|
2807 |
| |
- R.W. Helms, G. Hoffstaetter
Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
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Here we present a new algorithm for processing BPM signals and extracting orbit and phase data for very large beam excursion where the BPM response function changes nonlinearly with the beam position. Using two dimensional models of each BPM geometry, we calculate the button response using numerical solution of Laplace's equation and Green's reciprocity theorem. The difference between the calculated signals and the measured signals is minimized in real time to calculate the beam position and measurement errors. Using the derivatives of the response functions, we model the effect of beam shaking, and from it, calculate the betatron phase.
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