IBIC2014 - List of Keywords (high-voltage)

Paper	Title	Other Keywords	Page
MOPD15	CW Beam Stability Analysis in Time and Frequency Domain	electron, diagnostics, radiation, laser	179
	M. Kuntzsch, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P. Michel, R. Schurig, J. Teichert HZDR, Dresden, Germany
	The superconducting quasi CW Linac ELBE has been characterized in terms of energy and timing stability. The measurement results presented show a combination of a laser-based bunch arrival-time measurements (BAM), a fast beam position monitor (BPM) readout with single bunch resolution and a compression monitor (BCM) based on a fast pyro-electric detector. By changing the bunch compression factor a separation and identification of jitter sources has been achieved. The quasi CW mode of operation enables frequency domain data analysis with high dynamic range, which gives a better understanding of the main sources of jitter. Experimental results for both injectors (thermionic DC, superconducting RF) are presented.
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TUPD09	Vacuum Improvement of Bunch Shape Monitor for J-PARC Linac	vacuum, target, electron, linac	430
	A. Miura, Y. Kawane, N. Ouchi JAEA/J-PARC, Tokai-mura, Japan T. Miyao KEK, Ibaraki, Japan
	During the shutdown in summer 2012, we installed three BSMs (Bunch Shape Monitors) at the upstream of the ACS (Annular Coupled Structure Linac) section in order to perform longitudinal matching. ACS cavities were installed in summer 2013 to upgrade the Linac energy from 181 MeV to 400 MeV. Prior to the ACS installation, BSMs were installed and the beam commissioning of the BSMs has been conducted after the summer shutdown in 2012. During the BSM measurements, a problem of the degradation in vacuum conditions was found. One reason for this problem is the dark current resulting in the desorption of absorbed gas molecules. And another reason is the outgas released from materials when the high voltage and RF power are supplied for the electro-static lens and RF deflector, respectively. In order to solve this problem, BSMs were dismounted from the beam line and the off-line baking operations with outgas analysis had been performed to avoid the degradation of the vacuum. As the result of the gas analysis, we found that the outgas contains some heavy hydrocarbons. After these heavy hydrocarbon gaseous were removed and the vacuum level improved for about one order, we completed off-line baking. We will install all three BSMs in at the upstream of the ACS again with the additional vacuum pumps. This paper describes the vacuum degradation of the BSMs, how to conduct the baking operation for BSMs and its results. The improved set-ups of the vacuum are also introduced.
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WEPF08	Dosimetry of Pulsed Beams in Proton Therapy	proton, experiment, ion, electron	548
	J. van de Walle, Y. Claereboudt, G. Krier, D. Prieels IBA, Louvain-la-Neuve, Belgium G. Boissonnat, J. Colin, J.-M. Fontbonne LPC, Caen, France
	Ion Beam Applications (IBA) has developed in recent years the ProteusONE proton therapy system, which aims at reducing the cost and footprint of proton therapy systems, making them affordable and accessible to more patients worldwide. The heart of the ProteusONE system is a super conducting synchro-cyclotron (S2C2), which provides short (10 μs) proton bunches at 1 kHz. This is in contrast to the proton therapy systems including the IBA Cyclone230, which delivers a continuous beam. Nevertheless, the same average dose rates are provided by both systems. As a consequence, the instantaneous dose rates with the S2C2 are much higher and recombination losses in the large area beam diagnostics and dosimetry devices become non negligible. Since the proton charge which is send to a patient should be measured with high precision, these recombination losses have to be addressed carefully. In this work, a large area (30x30 cm²) and large gap (>3 mm) ionization chamber (IC) is presented which allows to quantify recombination losses in each beam pulse on-line. The principle is based on the introduction of two ionization volumes in series with slightly different gap sizes. The ratio of detected charges in both IC's is the basic observable which is used to recalculate the efficiency of each IC. The principle of this so-called "asymmetric ionization chamber" (AIC) was tested with beam from the S2C2 prototype. The results show that the efficiency can be re-calculated to 0.5% precision for voltages higher than 1000 V. Together with the experimental results, the theoretical background of the recombination losses will be discussed and it will be shown how this theory is applied in a robust and simple way to correct for these losses in the proton therapy system.
	Poster WEPF08 [0.999 MB]
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Paper

Title

Other Keywords

Page

MOPD15

CW Beam Stability Analysis in Time and Frequency Domain

electron, diagnostics, radiation, laser

179

M. Kuntzsch, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P. Michel, R. Schurig, J. Teichert
HZDR, Dresden, Germany

The superconducting quasi CW Linac ELBE has been characterized in terms of energy and timing stability. The measurement results presented show a combination of a laser-based bunch arrival-time measurements (BAM), a fast beam position monitor (BPM) readout with single bunch resolution and a compression monitor (BCM) based on a fast pyro-electric detector. By changing the bunch compression factor a separation and identification of jitter sources has been achieved. The quasi CW mode of operation enables frequency domain data analysis with high dynamic range, which gives a better understanding of the main sources of jitter. Experimental results for both injectors (thermionic DC, superconducting RF) are presented.

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TUPD09

Vacuum Improvement of Bunch Shape Monitor for J-PARC Linac

vacuum, target, electron, linac

430

A. Miura, Y. Kawane, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
T. Miyao
KEK, Ibaraki, Japan

During the shutdown in summer 2012, we installed three BSMs (Bunch Shape Monitors) at the upstream of the ACS (Annular Coupled Structure Linac) section in order to perform longitudinal matching. ACS cavities were installed in summer 2013 to upgrade the Linac energy from 181 MeV to 400 MeV. Prior to the ACS installation, BSMs were installed and the beam commissioning of the BSMs has been conducted after the summer shutdown in 2012. During the BSM measurements, a problem of the degradation in vacuum conditions was found. One reason for this problem is the dark current resulting in the desorption of absorbed gas molecules. And another reason is the outgas released from materials when the high voltage and RF power are supplied for the electro-static lens and RF deflector, respectively. In order to solve this problem, BSMs were dismounted from the beam line and the off-line baking operations with outgas analysis had been performed to avoid the degradation of the vacuum. As the result of the gas analysis, we found that the outgas contains some heavy hydrocarbons. After these heavy hydrocarbon gaseous were removed and the vacuum level improved for about one order, we completed off-line baking. We will install all three BSMs in at the upstream of the ACS again with the additional vacuum pumps. This paper describes the vacuum degradation of the BSMs, how to conduct the baking operation for BSMs and its results. The improved set-ups of the vacuum are also introduced.

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reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEPF08

Dosimetry of Pulsed Beams in Proton Therapy

proton, experiment, ion, electron

548

J. van de Walle, Y. Claereboudt, G. Krier, D. Prieels
IBA, Louvain-la-Neuve, Belgium
G. Boissonnat, J. Colin, J.-M. Fontbonne
LPC, Caen, France

Ion Beam Applications (IBA) has developed in recent years the ProteusONE proton therapy system, which aims at reducing the cost and footprint of proton therapy systems, making them affordable and accessible to more patients worldwide. The heart of the ProteusONE system is a super conducting synchro-cyclotron (S2C2), which provides short (10 μs) proton bunches at 1 kHz. This is in contrast to the proton therapy systems including the IBA Cyclone230, which delivers a continuous beam. Nevertheless, the same average dose rates are provided by both systems. As a consequence, the instantaneous dose rates with the S2C2 are much higher and recombination losses in the large area beam diagnostics and dosimetry devices become non negligible. Since the proton charge which is send to a patient should be measured with high precision, these recombination losses have to be addressed carefully. In this work, a large area (30x30 cm²) and large gap (>3 mm) ionization chamber (IC) is presented which allows to quantify recombination losses in each beam pulse on-line. The principle is based on the introduction of two ionization volumes in series with slightly different gap sizes. The ratio of detected charges in both IC's is the basic observable which is used to recalculate the efficiency of each IC. The principle of this so-called "asymmetric ionization chamber" (AIC) was tested with beam from the S2C2 prototype. The results show that the efficiency can be re-calculated to 0.5% precision for voltages higher than 1000 V. Together with the experimental results, the theoretical background of the recombination losses will be discussed and it will be shown how this theory is applied in a robust and simple way to correct for these losses in the proton therapy system.

Poster WEPF08 [0.999 MB]

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