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J. Seeman,
K. Adams,
G. Aharonian,
M. Billing,
E. Blum,
G. Decker,
M. Giannella,
G. Jackson,
R. Littauer,
B. McDaniel,
D. Morse,
S. Peck,
D. Rice,
L. Sakazaki,
R. Siemann,
R. Talman,
M. Tigner
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ABSTRACT: CESR has produced e+ e- collisions for high energy physics in the very productive T region (4.7 to 5.7 GeV per beam) since the fall of 1979. The peak luminosity recorded during physics data taking over that period is shown in Fig. 1. The dramatic increase in the luminosity has resulted from the reduction of Ãy* from 11 cm to 3 cm, an increase in ¿x *, and increases in the vertical aperture. Furthermore, observations of the beam-beam interaction show that the luminosity increases as the square of the beam current at low currents and linearly with current at high currents. These observations are consistent with a vertical beam size which is constant at low currents and increases linearly at high currents. A linearly increasing vertical beam size implies a constant vertical tune shift. The luminosity and the beam lifetime are limited by nongaussian tails which reach the physical aperture of CESR.
IEEE Transactions on Nuclear Science 09/1983; · 1.45 Impact Factor
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D. Rice,
G. Aharonian,
K. Adams,
M. Billing,
G. Decker,
C. Dunnam,
M. Giannella,
G. Jackson,
R. Littauer,
B. McDaniel,
D. Morse,
S. Peck,
L. Sakazaki, J. Seeman,
R. Siemann,
R. Talman
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ABSTRACT: We discribe various beam diagnostic devices in use at CESR, an 8 GeV electron-positron storage ring operating primarily in the 4.7 to 5.5 GeV beam energy range. Getting the last 20% of performance depends to some extent on empirical tuning and appropriate presentation of various parameters is very important. Several devices are most useful in machine studies and we describe their operation. The individually regulated quadrupoles in CESR provide unique opportunities for lattice measurements and calibration of beam position monitors.
IEEE Transactions on Nuclear Science 09/1983; · 1.45 Impact Factor
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IEEE Transactions on Nuclear Science 07/1981; · 1.45 Impact Factor
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D. Rice,
K. Adams,
M. Billing,
E. Blum,
R. Littauer,
B. McDaniel,
R. Meller,
D. Morse,
S. Peck,
S. Peggs, J. Seeman,
R. Siemann,
R. Talman,
M. Tigner,
E. vonBorstel
[show abstract]
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ABSTRACT: Single bunch current dependent phenomena have been examined in CESR, the Cornell Electron Storage Ring. These measurements are described and their results compared with predictions using the broad band resonator model of vacuum chamber impedance. A transient anti-damping effect in the vertical plane has been observed. The influence of various machine parameters on this effect will be described and a possible mechanism suggested.
IEEE Transactions on Nuclear Science 07/1981; · 1.45 Impact Factor
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J. Seeman,
K. Adams,
M. Billing,
E. Blum,
J. Gareyte,
J. Kirchgessner,
R. Littauer,
B. McDaniel,
R. Meller,
S. Peck,
S. Peggs,
D. Rice,
G. Rouse,
R. Siemann,
R. Sundelin,
R. Talman,
M. Tigner,
E. vonBorstel
[show abstract]
[hide abstract]
ABSTRACT: A transverse coupled bunch instability has been observed in the Cornell Electron Storage Ring CESR for both positrons and electrons. This instability shows strong horizontal or vertical coherent signals but very weak longitudinal signals. Positron injection, which requires sixty-one uniformly spaced bunches in CESR, was originally restricted by the enlarged effective horizontal beam size resulting from this instability. Although several cures have been discovered, only external octupoles provide a sufficient increase in the threshold and are compatible with injection. The theory for coupled bunch motion correctly predicts the instability threshold assuming that the driving mechanism is a 1140 MHz parasitic resonance in the RF cavity. Changes in the threshold with tune and octupole field strength are also correctly predicted.
IEEE Transactions on Nuclear Science 07/1981; · 1.45 Impact Factor
