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IT11 | Beam Diagnostics, Old and New
This is essentially a repeat of 'Beam Diagnostics Revisited', invited talk given at EPAC, Stockholm, June 1998 |
diagnostics, ion, linac, injection | 33 | ||
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The performance of accelerators and storage rings
depends critically on the completeness and quality of their
beam diagnostic systems. It is essential to equip them
from inception with all the instruments providing the
information on the properties and the behaviour of the
beams, needed during running-in, in operation, and for
development of performance towards the design goal and
often well beyond. Most of the instruments have proven
their worth since decades, but their power has been
increased through the modern means of data acquisition
and treatment. A few new instruments have made their
appearance in recent years, some still under development
and scrutiny for their operational value and precision. The
multi-accelerator chains of todays and tomorrows big
colliders have tight tolerances on beam loss and emittance
blow-up. For beam diagnostics this means a great
challenge for precision and consistency of measurements
all along the chain.
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CT01 | Measurements with a versatile Test Bench for Commissioning of the new GSI High Current Linac | rfq, ion, pick-up, diagnostics | 45 | ||
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For the commissioning of the new GSI prestripper a conventional
slitdetector system and a single shot pepperpot system has been
installed on a mobile test bench to measure intensity distributions in
the two transverse phase spaces. To determine intensity distributions
in the longitudinal phase space, including beam energy capacitive
pickups and newly developed diamond counters have been installed on the
test bench. The setup of the test bench provides also redundant
information for beam current, beam profile and beam position. The most
important features of all measuring systems including signal processing
and data evaluation are reported. First results from the commissioning
of the upgraded prestripper of the UNILAC at GSI are reported.
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CT02 | Determination of Radial Ion Beam Profile from the Energy Spectrum of Residual Gas Ions Accelerated in the Beam Potential | space-charge, ion, electron, acceleration | 50 | ||
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Residual gas ions (RGI) created from collisions of
positive beam ions (BI) with residual gas atoms are
accelerated out of the ion beam by its space charge
potential. It is demonstrated that with one-dimensional
radial symmetry the radial distributions of BI density and
space charge potential can be determined from the energy
distribution of RGI radially leaving the beam tube. RGI
energy spectra were taken with an electrostatic analyser of
Hughes-Rojansky type on a 10 keV 1.5 mA He+ beam.
For comparison the radial BI density distribution was
determined with a radial wire probe, an electron beam
probe and a beam transport calculation based on an
emittance measurement located downstream.
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CT11 | The OTR Screen Betatron Matching Monitor of the CERN SPS | injection, betatron, optics, scattering | 90 | ||
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In order to satisfy the stringent emittance
requirements of LHC, betatron matching monitors,
based on multiturn beam profile measurements, have
been proposed for the SPS and LHC. A test monitor
has been installed for evaluation in the CERN SPS first
in 1996 and improved in 1997. It is based on an OTR
screen and a fast beam profile acquisition system. It
has been used with proton beams to assess the quality
of the betatron matching from the PS to the SPS in
1998. Experience and results are presented.
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PS04 | Influence of transverse beam dimensions on beam position monitor signals | pick-up, quadrupole, synchrotron, instrumentation | 106 | ||
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In this paper we will evaluate the influence of
transverse beam dimensions on the signal functions of a
beam position monitor (BPM) with capacitive pick-up
electrodes. The error which occurs in the determination of
the beam position when disregarding these effects is
calculated as an example for the DELTA1 BPM.
The possibility to use this effect for the measurement
of the beam size / emittance is discussed.
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PS13 | Analysis of the proton beam in the DESY transport lines by video readout | proton, background, luminosity, vacuum | 129 | ||
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Injection efficiency, beam optic matching and
emittance preservation are very important parameters in
achieving a high luminosity in large proton
accelerators. We improved the analysing system of the
phosphor screen readout of the proton transport lines in
the accelerator chain of HERA with respect to the
parameters above. The screens are read out by simple
CCD video cameras. The signals are stored in local
frame grabbers. An analogue output of the stored image
is multiplexed and read-out by a fast PCI frame grabber
card in a PC. The beam orbit and the beam emittance
can be measured from each screen. A Visual Basic
program is used to displays the trajectory and the
envelope of the beam from a single transfer. The same
program helps to drive bumps to achieve a proper
steering through the line. The beam width can be
measured from selected screens to calculate the
emittance and other beam parameters including their
errors. The read out and analysing system will be
described and measurements will be shown.
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PT07 | Emittance measurements at the new UNILAC-pre-stripper using a pepper-pot with a PC-controlled CCD-camera | ion, laser, linac, ion-source | 171 | ||
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The complex mathematical algorithms and procedures
to extract emittance data from intensity distributions
measured with a single shot pepper-pot device are
described. First results of mathematical evaluation from
the commissioning of the new GSI pre-stripper linac
structures are presented.
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PT10 | Emittance and dispersion measurements at TTF | quadrupole, dipole, linac, acceleration | 180 | ||
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It is well known that beam dispersion , along with the
Twiss parameters and emittance, contributes to the beam
spot size. So that, in general, anomalous dispersion is an
undesirable event and must be minimized by careful tuning
the machine. If not, when the spot size is used to infer
beam emittances, as it is the case of the "quadrupole
scan" method, basically employed at TTF, the unknown
dispersion can lead to overestimated values for the emittance.
This paper presents the first attempt to determine the
dispersion function at several points of the TTF Linac and
to separate its contribution to the local emittance measurement,
performed by means of the OTR imaging technique.
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PT16 | Status of the delta synchrotron light-monitoring-system | synchrotron, radiation, synchrotron-radiation, shielding | 196 | ||
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A synchrotron radiation source like DELTA needs an optical
monitoring system to measure the beam size at different
points of the ring with high resolution and accuracy.
The measurements with the present synchrotron light
monitors show that beam sizes larger than 250 μm can be
measured. The measured emittance is of the order of the
theoretical values of the optics and goes down to 8 nm rad.
The magnification of the system can simply be increased
by adding another lens to measure smaller emittances and
beamsizes down to 100 μm. In this case you still have
an optical image of the beam available, but sometimes the
position of the camera has to be adapted due to the great
magnification of the optical system. The image processing
system which is based on a VME Framegrabber makes a
two dimensional gaussian fit to the images from different
synchrotron light-monitors.
First tests with monochromatic components of the synchrotron
radiation (500 nm and 550 nm) and with short
time cameras (shutter time down to 1/10000 s) have been
performed. A two-dimensional PSD has been installed to
measure slow beam motion. To measure small beam sizes,
especially in the vertical plane, diffraction elements will be
used.
This paper gives an overview over the present installation
and the results.
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