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Bergoz Beam Position Monitors
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 The
Bergoz Log-Ratio Beam Position Monitor
(LR-BPM) is an electronics module designed for fast processing
of beam position signals. To acheive this, the signals
are parallel processed in a single pass position measurement.
It is a non-intercepting system that is suitable for use
in most Linacs, transfer lines, first turns, boosters
and fast-cycling synchrotrons
For Beam Position Monitoring in electron and positron
Storage Rings, please refer to the MX-BPM.
The LR-BPM is in use at <<Insert customers using
the LR-BPM here>>.
| The
LR-BPM features |
| • |
Input
signals are parallel processed allowing a single-pass
position measurement. |
| • |
Beam
charge range > 500 |
| • |
Beam-based
center determination |
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Bunches
at any repetition rate up to 500 MHz Individual
bunches can be distinguished from one another up
to 5 MHz repetition |
| • |
Log-Ratio
BPM is plug compatible with Bergoz' multiplexed
BPM |
| • |
L-band,
S-band, X-band beams can be processed provided bunch
groups are short (<3 ns) |
| • |
±2V
X and Youtputs are held until the next bunch when
Sample & Hold mode (optional) is activated. |
| • |
Provides
log signal from each pickup electrode for computer
analysis, with 5 MHz bandwidth. |
| • |
Beam-based
center determiuation accessory equalizes pickup
signals to simulate beam on center. |
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The
Log-Ratio Beam Position Monitor (LR-BPM) is an electronics
module for fast analog processing of beam pickup
signals |
| • |
LR-BPM
may be custom-built on daughter card for installation
on user's DSP motherboards |
| • |
Cables
length matching not critical pickup signals don't
need to be in phase |
Operating
Principle
Based on the pioneering work of Robert E. Shafer at Los
Alamos Laboratory, the Log-Ratio BPM derives beam position
from logarithm of the ratio of opposite pickup signals
Log(A/B).
Position measured by this method is more linear, over
a wider range, than difference-over-sum.
The position of the beam from rotated pickups is obtained
by axes translation to the vertical resp horizontal plane
by wideband analog circuits
Signal Processing
The signals from the pickups are stretched to produce
bursts. This is essential to measure the single pass of
a bunch. Four parallel logarithmic amplifiers detect the
burst envelopes. Amplifiers' response is log of amplitude
and the logs of opposite pickups are subtracted. If pickups
are rotated, axes are transtated to obtain X and Y positions.
The process is all wideband analog.
Beam-based Center Determination
Differences between parallel processing channels can be
nearly eliminated by using the Beam-based center determination
accessory. It equalizes opposite pickup signals to simulate
beam on center. The zero offsets can thus be measured
at regular intervals under user's control and subtracted
from subsequent readings. Signals entering the equalizer
must be in phase. It is controlled by the LR-BPM module,
via the input cables. Center determination and beam position
measurement may be interleaved. |
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