| Paper |
Title |
Other Keywords |
Page |
| CT06 |
The Measurement of Q' And Q'' in the CERN-SPS by Head-Tail Phase Shift Analysis
|
instrumentation, diagnostics, chromatic-effects |
79 |
| |
- R. Jones, H. Schmickler
CERN, Geneva, Switzerland
| |
A so-called "Head-Tail" chromaticity measurement system has recently
been installed in the CERN-SPS, which allows the chromaticity (Q’) to be
calculated from several hundred turns of data after transverse
excitation. The measurement relies on the periodic dephasing and
rephasing that occurs between the head and tail of a single bunch for
non-zero chromaticity. By measuring the turnby-turn position data from
two longitudinal positions in a bunch it is possible to extract the
relative dephasing of the head and the tail, and so to determine the
chromaticity. In addition, by changing the orbit of the circulating beam
this technique allows the variation of chromaticity with radial position
(Q’’) to be measured with a much higher resolution than is currently
possible using RF modulation. This paper describes this "Head-Tail"
measurement technique and discusses some recent results obtained using
prototype LHC beam (25 ns spacing) in the CERN-SPS.
|
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| CT07 |
Excitation of Large Transverse Beam Oscillations without Emittance Blow-Up Using the "AC-Dipole" Principle
|
instrumentation, diagnostics, emittance |
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.
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|
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| CT08 |
Measuring Beta-Functions with K-Modulation
|
instrumentation, diagnostics, emittance |
85 |
| |
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