Paper |
Title |
Page |
CT07 |
Excitation of Large Transverse Beam Oscillations without Emittance Blow-Up Using the "AC-Dipole" Principle
|
82 |
|
- O. Berrig, W. Höfle, R. Jones, J. Koopman, J.-P. Koutchouk, F. Schmidt
CERN, Geneva, Switzerland
|
|
|
The so-called "AC-Dipole" principle allows the excitation of transverse
oscillations to large (several σ) excursions without emittance
blow-up. The idea was originally proposed and tested at BNL for
resonance crossing with polarized beams, using an orbit corrector dipole
with an excitation frequency close to the betatron tune, hence
"AC-Dipole". This method of beam excitation has several potential
applications in the LHC, such as phase advance and β-measurements,
dynamic aperture studies and the investigation of resonance strengths.
The technique was recently tested in the CERN-SPS using the transverse
damper as an "AC-Dipole" providing the fixed frequency excitation.
results from this experiment are presented, along with an explanation of
the underlying principle.
|
|
CT08 |
Measuring Beta-Functions with K-Modulation
|
85 |
|
- O. Berrig, C. Fischer, H. Schmickler
CERN, Geneva, Switzerland
|
|
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The precise measurement of the local value of the beta-function at the
place of a beam size monitor is necessary for the precise determination
of the beam emittance. We developed a new method for the measurement of
the beta-function by using of continuous square-wave modulation of the
force of the quadrupole and by continuous tune tracking. Measurements
were performed at LEP in order to evaluate the precision that can be
achieved with this method in the LHC. The paper describes the method and
discusses in details the results obtained at LEP for colliding and
non-colliding beams.
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