| Paper |
Title |
Page |
| CT10 |
Real Time Display of the Vertical Beam Sizes in LEP Using the BEXE X-Ray Detector and Fast VME Based Computers
|
87 |
| |
- R. Jones, A. Manarin, G. Pignard, E. Rossa, H. Schmickler, M. Sillanoli, C. Surback
CERN, Geneva, Switzerland
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Fast X-ray detectors based on CdTe photoconductors
have been installed in LEP since the beginning of its
operation in 1989. The angular divergence of the high
energy photons from the synchrotron radiation (x-rays)
and the narrow spacing of the 64 photoconductors of the
detector allow a good measurement of vertical beam
profiles down to an rms beam size of 300 mm.
This paper presents some specific parameters and
experimental results of an upgrade program in which the
local processing power of the front-end electronics has
been increased by a factor 50. Such a powerful tool has
allowed a real time display of the time evolution of the
vertical beam sizes. An online correlation plot between
the electron and positron beam sizes (turn by turn) is
also displayed.
These online video images are available in the LEP
control room and are used in daily operation for
luminosity optimisation.
|
|
| PS12 |
Performance of the new SPS beam position orbit system (MOPOS)
|
126 |
| |
- C. Boccard, T. Bogey, J. de Vries, S. Jackson, R. Jones, J.P. Papis, W. Rawnsley, K. Rybaltchenko, H. Schmickler
CERN, Geneva, Switzerland
|
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| |
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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