IBIC2023, Saskatoon, Canada
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EXPANSION OF THE ΜTCA BASED DIRECT SAMPLING LLRF AT
MEDAUSTRON FOR HADRON SYNCHROTRON APPLICATIONS
M. Wolf∗ , M. Cerv, C. Kurfuerst, S. Myalski, M. Repovz, C. Schmitzer
EBG MedAustron GmbH, Wr. Neustadt, Austria
A. Bardorfer, B. Baricevic, P. Leban, P. Paglovec, M. Skabar
Instrumentation Technologies, Solkan, Slovenia
Abstract
The MedAustron Ion Therapy Centre is a synchrotronbased particle therapy facility located in Lower Austria,
which delivers proton and carbon ion beams for cancer treatments. Currently the facility treats over 400 patients per
year and is expected to double this number in the future. Six
years since the start of clinical operation, MedAustron isexperiencing end-of-life issues concerning the digital Low
Level RF components in the injector and the synchrotron.
Replacements for these applications are under development
and the chosen hardware is suitable to also update multiple beam diagnostic devices in the facility. Main targets
for updates are the Schottky monitors, which were neverproperly integrated into the MedAustron Control system andthe position pickup measurement system, which currently
does not support turn by turn measurements. Comparison
measurements with other state of the art diagnostic devices
are ongoing to demonstrate the capabilities of the generichardware. Furthermore, these measurements should show
the increased usability and diagnostic potential compared to
the legacy devices.

amplifiers. The distribution amplifiers generate multiple
copies of the pickups signals. Spare outputs of the distribution amplifiers are used to parasitically measure the twohorizontal pickups in high and low dispersion regions.

Digital Data Processing of thePosition Measurement
The output of the position measurement system is digitized with off the shelf hardware from Vadatech which waspresented in Ref. [1]. For the beam position measurement
one AMC560 Carrier card and one FMC231 AD/DA converter card is used. The signals produced by the distribution amplifiers are directly sampled and then demodulated
to baseband signals using the revolution frequency of thesynchrotron. The resulting amplitude of the delta signal
is divided by the amplitude of the sum signal, to calculate
position information independent of the beam current. The
results of this calculation can then be calibrated to represent
absolute position data. This calibration will be finalized in
the future.

INTRODUCTION
MedAustron and Instrumentation Technologies continued
to work on a LLRF and beam diagnostic solution to replace
all RF applications used at MedAustron and already presented in the last years [1–3]. In the current paper new beamdiagnostic usecases in the MedAustron Synchrotron will beshown and measurement results of Schottky detectors andclassical Shoebox Pickups will be compared to other off theshelf equipment.

MEASUREMENT SETUP
Position Measurement System
The MedAustron Synchrotron contains multiple beam position monitors in form of Shoebox Pickups. These Pickups
are located in different dispersion regions of the Synchrotron
and can be used to measure the orbit of the beam circulatingin the synchrotron. Head amplifiers are connected to thesepickups with short cables to keep the interference and cableinfluences at a minimum. These head amplifiers generate
sum and delta signals out of the pickup plate signals. Afterwards these sum and delta signals are forwarded out of
the synchrotron hall and further amplified in distribution∗ markus.wolf@medaustron.atFigure 1: Qualitative position measurement in high and low
dispersion regions of the synchrotron.

Schottky Monitors
The Schottky monitors are directly connected to standard
low noise amplifiers (FEMTO- HVA-200M-40-F) and afterwards connected to the digitizer hardware outside of thesynchrotron hall. In this setup sum and delta signals arecalculated after digitizing the signals.
MOP01302 Beam Position Monitors

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12th Int. Beam Instrum. Conf.
ISBN: 9 7 8 - 3 - 9 5 4 5 0 - 2 3 6 - 3

12th Int. Beam Instrum. Conf.
ISBN: 9 7 8 - 3 - 9 5 4 5 0 - 2 3 6 - 3

IBIC2023, Saskatoon, Canada
JACoW Publishing
ISSN: 2 6 7 3 - 5 3 5 0d o i : 1 0 . 1 8 4 2 9 / J A C o W - I B I C 2 0 2 3 - M O P 0 1 3

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0.25Time [s]Content from this work may be used under the terms of the CC-BY-4.0 licence (© 2023). Any distribution of this work must maintain attribution to the author(s), title of the work, publisher, and DOIHadron Vertical Schottky

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Figure 2: Waterfall diagram and frequency analysis of beam injection with the Libera Hadron.

Digital Data Processing of theSchottky Measurements
The schottky plate data is directly sampled by the µTCA
based Vadatech solution and for comparison also by a Libera
Hadron. Sum and delta signals are calculated in the digitaldomain and the results are then plotted in form of waterfall
diagrams showing how the particle bunch changes its shapeinside the synchrotron. Additionally the data is fed intoa FFT algorithm, which should provide information about
the revolution frequency, the synchrotron frequency and thebeam tune.

MEASUREMENTS
Position Measurement
The position measurement (Fig. 1) shows the injection,
adiabatic capture and the start of the acceleration inside thesynchrotron. Due to a small mismatch of the Dipole field
and the injection energy the beam position drifts a little bitat the beginning. Only after the radial loop is turned on theposition stabilizes till the end of the measurement. At thebeginning of the acceleration (at 100 ms) field ramping of themagnets is not exactly synchronous to the beam acceleration
resulting in a small oscillation seen in the low Dispersion
area.

Schottky Measurements
The schottky measurements are done with two different
measurement devices and show the beam bunch in a waterfall
diagram after capture (MedAustron uses a coasting injection)and before the acceleration starts. Dipole and quadrupole oscillations are clearly visible with both measurement devices.

Both of the devices show a good resolution of the beam,
which should make a tomography of the beam possible.
The FFT plots show the whole range from the beam injection, the capture and the start of the acceleration. Comparedto each other both devices show a good resolution for thesum signals. Differences can only be seen at the Delta plots.
There it looks like the Hadron (Fig. 2) exhibits a bit morenoise compared to the Vadatech solution (Fig. 3) over almost
the whole frequency range shown. Unfortunately none of thetwo devices can clearly show the beam tune while the beam
is captured and without an excitation kick (either by a kicker
or transversal RF excitation). Only at the very beginning of
the measurement (first 10 ms) a small peak could be seen,
which might be the beam tune. Further measurements will
be needed to verify if these peaks are really the beam tune
and to identify system improvements, which might show thebeam tune more clearly.

RESULTS AND OUTLOOKThe chosen new hardware for the MedAustron RF applications continues to improve beam diagnostic capabilities
available at the facility. The results show the suitability forthe low frequency range needed at MedAustron and the beam
resolution and turn by turn measurement bring new diagnostics like a beam tomography within reach. Nonethelessalready the shown measurements increase the knowledge
about the machine behavior compared to the legacy beamdiagnostic devices.

MOP01364

02 Beam Position Monitors

12th Int. Beam Instrum. Conf.
ISBN: 9 7 8 - 3 - 9 5 4 5 0 - 2 3 6 - 3

IBIC2023, Saskatoon, Canada
JACoW Publishing
ISSN: 2 6 7 3 - 5 3 5 0d o i : 1 0 . 1 8 4 2 9 / J A C o W - I B I C 2 0 2 3 - M O P 0 1 3

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Figure 3: Waterfall diagram and frequency analysis of beam injection with the Vadatech µTCA solution.

REFERENCES[1] M. Wolf et al., “Development and Integration of a New LowLevel RF System for MedAustron”, in Proc. LINAC’22, Liverpool, UK, Aug.-Sep. 2022, pp. 764–766.
doi:10.18429/JACoW-LINAC2022-THPOPA12[2] M. Repov et al., “Development of a New Measurement Systemfor Beam Position Pickups in the LINAC and Beam Energy

Measurement (Time of Flight) in the MEBT for Medaustron”,in Proc. IBIC’22, Kraków, Poland, Sep. 2022, pp. 238–240.
doi:10.18429/JACoW-IBIC2022-TUP10[3] M. Wolf et al., “Expansion of the µTCA based direct sampling LLRF at MedAustron for hadron synchrotron applications”, presented at the IPAC’23, Venice, Italy, May 2023,
paper THPA091, to be published.

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MTCA Vertical Schottky