| Paper |
Title |
Other Keywords |
Page |
| CT08 |
Adaptive Optics for the LEP 2 Synchrotron Light Monitors
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synchrotron, radiation, synchrotron-radiation, optics |
77 |
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- G. Burtin, R.J. Colchester, G. Ferioli, J.J. Gras, R. Jung, J.M. Vouillot
CERN, Geneva, Switzerland
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The image obtained with the LEP synchrotron
radiation telescopes deteriorates, giving multiple and
deformed images, when the beam energy goes beyond
80 GeV at beam currents above 2 mA. This problem is
due to the deformation of the light extracting beryllium
mirror, by as little as 1 mm, and had been predicted at
the design stage. To overcome this problem, several
changes together with an adaptive optics set-up have
been introduced. These essentially consist of a
cylindrically deformable mirror to compensate the
cylindrical deformation of the beryllium mirror and a
movable detector to compensate the spherical
deformation. Both components are continuously
adjusted as a function of beam current and energy.
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| PS12 |
Performance of the new SPS beam position orbit system (MOPOS)
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ion, pick-up, heavy-ion, proton |
126 |
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- C. Boccard, T. Bogey, J. de Vries, S. Jackson, R. Jones, J.P. Papis, W. Rawnsley, K. Rybaltchenko, H. Schmickler
CERN, Geneva, Switzerland
| |
The orbit and trajectory measurement system COPOS
of the CERN SPS accelerator has been in operation since
the construction of the machine in 1976. Over the years
the system has been slightly modified in order to follow
the evolving demands of the machine, in particular for its
operation as a p-pbar collider and, since 1991, for the
acceleration of heavy ions.
In 1995 the performance of the system was reviewed
and the following shortcomings were identified:
- lack of turn-by-turn position measurements due to the
1ms integration time of the voltage to frequency
converters used for the analogue to digital conversion (to
be compared with a revolution time of 23 ms),
- ageing effects on the 200 MHz resonating input filters,
which had over the years drifted out of tolerance. As a
consequence the signal to noise ratio, the linearity and
the absolute precision were affected.
- the calibration system based on electromechanical relays
had become very unreliable, such that frequent
calibrations were no longer possible,
- a remote diagnostic for the observation of timing
signals relative to the beam signals was missing.
For the above reasons a large-scale upgrade program
was launched, the results of which are described in the
following sections.
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