IPAC2016 - List of Authors (Damerau, H.)

Paper	Title	Page
MOPOR012	Study of the Beam-Cavity Interaction in the PS 10 MHz RF System	618
	G. Favia, H. Damerau, M. Morvillo, C. Rossi CERN, Geneva, Switzerland M. Migliorati University of Rome "La Sapienza", Rome, Italy
	The eleven main accelerating cavities of the Proton Synchrotron (PS) at CERN consist of two ferrite-loaded coaxial λ/4 resonators each. Both resonators oscillate in phase, as their gaps are electrically connected by short bars. They are in addition magnetically coupled via the bias loop used for cavity tuning. The cavities are equipped with a wide-band feedback system, limiting the beam loading, and a further reduction of the beam induced voltage is achieved by relays which short-circuit each half-resonator gap when the cavity is not in use. Asymmetries of the beam induced voltage observed in the two half-cavities indicate that the coupling between the two resonators is not as tight as expected. The total cavity impedance coupling to the beam may be affected differently by the contributions of both resonators. A dedicated measurement campaign with high-intensity proton beam and numerical simulation have been performed to investigate the beam-cavity interaction. This paper reports the result of the study and the work aiming at the development of a model of the system, including the wide-band feedback, which reproduces this interaction.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR012
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MOPOR013	The PS 10 MHz High Level RF System Upgrade	622
	G. Favia, H. Damerau, V.D. Desquiens, S. Energico, M. Morvillo, D. Perrelet, C. Rossi CERN, Geneva, Switzerland
	In view of the upgrade of the injectors for the High Luminosity LHC, significantly higher bunch intensity is required for LHC-type beams. In this context an upgrade of the main accelerating RF system of the Proton Synchrotron (PS) is necessary, aiming at reducing the cavity impedance which is the source of longitudinal coupled-bunch oscillations. These instabilities pose as a major limitation for the increase of the beam intensity as planned after LS2. The 10 MHz RF system consists in 11 ferrite loaded cavities, driven by tube-based power amplifiers for reasons of radiation hardness. The cavity-amplifier system is equipped with a wide-band feedback that reduces the beam induced voltage. A further reduction of the beam loading is foreseen by upgrading the feedback system, which can be reasonably achieved by increasing the loop gain of the existing amplification chain. This paper describes the progress of the design of the upgraded feedback system and shows the results of the tests on the new amplifier prototype, installed in the PS during the 2015-16 technical stop. It also reports the first results of its performance with beam, observed in the beginning of the 2016 run.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR013
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MOPOR014	Measurements of the CERN PS Longitudinal Resistive Coupling Impedance	626
	M. Migliorati, N. Biancacci, H. Damerau, G. Sterbini CERN, Geneva, Switzerland M. Migliorati University of Rome "La Sapienza", Rome, Italy M. Migliorati, L. Ventura INFN-Roma1, Rome, Italy S. Persichelli University of Rome La Sapienza, Rome, Italy
	The longitudinal coupling impedance of the CERN PS has been studied in the past years in order to better understand collective effects which could produce beam intensity limitations for the LHC Injectors Upgrade project. By measuring the incoherent quadrupole synchrotron frequency vs beam intensity, the inductive impedance was evaluated and compared with the impedance model obtained by taking into account the contribution of the most important machine devices. In this paper, we present the results of the measurements performed during a dedicated campaign, of the real part of the longitudinal coupling impedance by means of the synchronous phase shift vs beam intensity. The phase shift has been measured by using two different techniques: in one case, we injected in the machine two bunches, one used as a reference with constant intensity, and the second one changing its intensity; in the second case, more conventional, we measured the bunch position with respect to the RF signal of the 40 MHz cavities. The obtained dependence of the synchrotron phase with intensity is then related to the loss factor and the resistive coupling impedance, which is compared to the real part of the PS impedance model.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR014
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MOPOY059	LHC Injectors Upgrade (LIU) Project at CERN	992
	E.N. Shaposhnikova, J. Coupard, H. Damerau, A. Funken, S.S. Gilardoni, B. Goddard, K. Hanke, L. Kobzeva, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, M. Vretenar CERN, Geneva, Switzerland
	A massive improvement program of the LHC injector chain is presently being conducted under the LIU project. For the proton chain, this includes the replacement of Linac2 with Linac4 as well as all necessary upgrades to the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS), aimed at producing beams with the challenging High Luminosity LHC (HL-LHC) parameters. Regarding the heavy ions, plans to improve the performance of Linac3 and the Low Energy Ion Ring (LEIR) are also pursued under the general LIU program. The full LHC injection chain returned to operation after Long Shutdown 1, with extended beam studies taking place in Run 2. A general project Cost and Schedule Review also took place in March 2015, and several dedicated LIU project reviews were held to address issues awaiting pending decisions. In view of these developments, 2014 and 2015 have been key years to define a number of important aspects of the final LIU path. This paper will describe the reviewed LIU roadmap and revised performance objectives of the main upgrades, including the work status and outlook in terms of the required installation and commissioning stages.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY059
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TUOBB03	CERN AWAKE Facility Readiness for First Beam	1071
	C. Bracco, M. Bernardini, A.C. Butterworth, H. Damerau, S. Döbert, V. Fedosseev, E. Feldbaumer, E. Gschwendtner, W. Höfle, A. Pardons, E.N. Shaposhnikova, H. Vincke CERN, Geneva, Switzerland
	The AWAKE project at CERN was approved in August 2013 and since then a big effort was made to be able to probe the acceleration of electrons before the "2019-2020 Long Shutdown". The next steps in this challenging schedule will be a dry run of all the beam line systems, at the end of the HW commissioning in June 2016, and the first proton beam sent to the plasma cell one month later. The current status of the project is presented together with an outlook over the foreseen works for operation with electrons in 2018.
	Slides TUOBB03 [10.682 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOBB03
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TUPMR027	CERN's Fixed Target Primary Ion Programme	1297
	D. Manglunki, M.E. Angoletta, J. Axensalva, G. Bellodi, A. Blas, M.A. Bodendorfer, T. Bohl, S. Cettour-Cave, K. Cornelis, H. Damerau, I. Efthymiopoulos, A. Fabich, J.A. Ferreira Somoza, A. Findlay, P. Freyermuth, S.S. Gilardoni, S. Hancock, E.B. Holzer, S. Jensen, V. Kain, D. Küchler, A.M. Lombardi, A.I. Michet, M. O'Neil, S. Pasinelli, R. Scrivens, R. Steerenberg, G. Tranquille CERN, Geneva, Switzerland
	The renewed availability of heavy ions at CERN for the needs of the LHC programme has triggered the interest of the fixed-target community. The project, which involves sending several species of primary ions at various energies to the North Area of the Super Proton Synchrotron, has now entered its operational phase. The first argon run, with momenta ranging from 13 AGeV/c to 150 AGeV/c, took place from February 2015 to April 2015. This paper presents the status of the project, the performance achieved thus far and an outlook on future plans.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR027
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TUPOR028	Excitation of Longitudinal Coupled-bunch Oscillations with the Wide-band Cavity in the CERN PS	1724
	L. Ventura, M. Migliorati INFN-Roma1, Rome, Italy H. Damerau, M. Migliorati, G. Sterbini CERN, Geneva, Switzerland M. Migliorati University of Rome "La Sapienza", Rome, Italy
	Longitudinal coupled-bunch oscillations in the CERN Proton Synchrotron have been studied in the past years and they have been recognized as one of the major challenges to reach the high brightness beam required by the High Luminosity LHC project. In the frame of the LHC Injectors Upgrade project in 2014 a new wide-band Finemet cavity has been installed in the Proton Synchrotron as a part of the coupled-bunch feedback system. To explore the functionality of the Finemet cavity during 2015 a dedicated measurement campaign has been performed. Coupled-bunch oscillations have been excited with the cavity around each harmonic of the revolution frequency with both a uniform and nominal filling pattern. In the following the measurements procedure and results are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR028
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THPMY039	RF Synchronization and Distribution for AWAKE at CERN	3743
	H. Damerau, D. Barrientos, T. Bohl, A.C. Butterworth, S. Döbert, W. Höfle, J.C. Molendijk, S.F. Rey, U. Wehrle CERN, Geneva, Switzerland J.T. Moody, P. Muggli MPI-P, München, Germany
	The Advanced Wakefield Experiment at CERN (AWAKE) requires two particle beams and a high power laser pulse to arrive simultaneously in a rubidium plasma cell. A proton bunch from the SPS extracted about once every 30 seconds must be synchronised with the AWAKE laser and the electron beam pulsing at a repetition rate of 10 Hz. The latter is directly generated using a photocathode triggered by part of the laser light, but the exact time of arrival in the plasma cell still depends on the phase of the RF in the accelerating structure. Each beam requires RF signals at characteristic frequencies: 6 GHz, 88.2 MHz and 10 Hz for the synchronisation of the laser pulse, 400.8 MHz and 8.7 kHz for the SPS, as well as 3 GHz to drive the accelerating structure of the electron beam. A low-level RF system has been designed to generate all signals derived from a common reference. Additionally precision triggers, synchronous with the arrival of the beams, will be distributed to beam instrumentation equipment. To suppress delay drifts of the several kilometer long optical fibres between AWAKE and the SPS RF systems, a compensated fibre link is being developed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY039
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Study of the Beam-Cavity Interaction in the PS 10 MHz RF System

618

G. Favia, H. Damerau, M. Morvillo, C. Rossi
CERN, Geneva, Switzerland
M. Migliorati
University of Rome "La Sapienza", Rome, Italy

The eleven main accelerating cavities of the Proton Synchrotron (PS) at CERN consist of two ferrite-loaded coaxial λ/4 resonators each. Both resonators oscillate in phase, as their gaps are electrically connected by short bars. They are in addition magnetically coupled via the bias loop used for cavity tuning. The cavities are equipped with a wide-band feedback system, limiting the beam loading, and a further reduction of the beam induced voltage is achieved by relays which short-circuit each half-resonator gap when the cavity is not in use. Asymmetries of the beam induced voltage observed in the two half-cavities indicate that the coupling between the two resonators is not as tight as expected. The total cavity impedance coupling to the beam may be affected differently by the contributions of both resonators. A dedicated measurement campaign with high-intensity proton beam and numerical simulation have been performed to investigate the beam-cavity interaction. This paper reports the result of the study and the work aiming at the development of a model of the system, including the wide-band feedback, which reproduces this interaction.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOR013

The PS 10 MHz High Level RF System Upgrade

622

G. Favia, H. Damerau, V.D. Desquiens, S. Energico, M. Morvillo, D. Perrelet, C. Rossi
CERN, Geneva, Switzerland

In view of the upgrade of the injectors for the High Luminosity LHC, significantly higher bunch intensity is required for LHC-type beams. In this context an upgrade of the main accelerating RF system of the Proton Synchrotron (PS) is necessary, aiming at reducing the cavity impedance which is the source of longitudinal coupled-bunch oscillations. These instabilities pose as a major limitation for the increase of the beam intensity as planned after LS2. The 10 MHz RF system consists in 11 ferrite loaded cavities, driven by tube-based power amplifiers for reasons of radiation hardness. The cavity-amplifier system is equipped with a wide-band feedback that reduces the beam induced voltage. A further reduction of the beam loading is foreseen by upgrading the feedback system, which can be reasonably achieved by increasing the loop gain of the existing amplification chain. This paper describes the progress of the design of the upgraded feedback system and shows the results of the tests on the new amplifier prototype, installed in the PS during the 2015-16 technical stop. It also reports the first results of its performance with beam, observed in the beginning of the 2016 run.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR013

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOR014

Measurements of the CERN PS Longitudinal Resistive Coupling Impedance

626

M. Migliorati, N. Biancacci, H. Damerau, G. Sterbini
CERN, Geneva, Switzerland
M. Migliorati
University of Rome "La Sapienza", Rome, Italy
M. Migliorati, L. Ventura
INFN-Roma1, Rome, Italy
S. Persichelli
University of Rome La Sapienza, Rome, Italy

The longitudinal coupling impedance of the CERN PS has been studied in the past years in order to better understand collective effects which could produce beam intensity limitations for the LHC Injectors Upgrade project. By measuring the incoherent quadrupole synchrotron frequency vs beam intensity, the inductive impedance was evaluated and compared with the impedance model obtained by taking into account the contribution of the most important machine devices. In this paper, we present the results of the measurements performed during a dedicated campaign, of the real part of the longitudinal coupling impedance by means of the synchronous phase shift vs beam intensity. The phase shift has been measured by using two different techniques: in one case, we injected in the machine two bunches, one used as a reference with constant intensity, and the second one changing its intensity; in the second case, more conventional, we measured the bunch position with respect to the RF signal of the 40 MHz cavities. The obtained dependence of the synchrotron phase with intensity is then related to the loss factor and the resistive coupling impedance, which is compared to the real part of the PS impedance model.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR014

Export •

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MOPOY059

LHC Injectors Upgrade (LIU) Project at CERN

992

E.N. Shaposhnikova, J. Coupard, H. Damerau, A. Funken, S.S. Gilardoni, B. Goddard, K. Hanke, L. Kobzeva, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, M. Vretenar
CERN, Geneva, Switzerland

A massive improvement program of the LHC injector chain is presently being conducted under the LIU project. For the proton chain, this includes the replacement of Linac2 with Linac4 as well as all necessary upgrades to the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS), aimed at producing beams with the challenging High Luminosity LHC (HL-LHC) parameters. Regarding the heavy ions, plans to improve the performance of Linac3 and the Low Energy Ion Ring (LEIR) are also pursued under the general LIU program. The full LHC injection chain returned to operation after Long Shutdown 1, with extended beam studies taking place in Run 2. A general project Cost and Schedule Review also took place in March 2015, and several dedicated LIU project reviews were held to address issues awaiting pending decisions. In view of these developments, 2014 and 2015 have been key years to define a number of important aspects of the final LIU path. This paper will describe the reviewed LIU roadmap and revised performance objectives of the main upgrades, including the work status and outlook in terms of the required installation and commissioning stages.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY059

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TUOBB03

CERN AWAKE Facility Readiness for First Beam

1071

C. Bracco, M. Bernardini, A.C. Butterworth, H. Damerau, S. Döbert, V. Fedosseev, E. Feldbaumer, E. Gschwendtner, W. Höfle, A. Pardons, E.N. Shaposhnikova, H. Vincke
CERN, Geneva, Switzerland

The AWAKE project at CERN was approved in August 2013 and since then a big effort was made to be able to probe the acceleration of electrons before the "2019-2020 Long Shutdown". The next steps in this challenging schedule will be a dry run of all the beam line systems, at the end of the HW commissioning in June 2016, and the first proton beam sent to the plasma cell one month later. The current status of the project is presented together with an outlook over the foreseen works for operation with electrons in 2018.

Slides TUOBB03 [10.682 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOBB03

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TUPMR027

CERN's Fixed Target Primary Ion Programme

1297

D. Manglunki, M.E. Angoletta, J. Axensalva, G. Bellodi, A. Blas, M.A. Bodendorfer, T. Bohl, S. Cettour-Cave, K. Cornelis, H. Damerau, I. Efthymiopoulos, A. Fabich, J.A. Ferreira Somoza, A. Findlay, P. Freyermuth, S.S. Gilardoni, S. Hancock, E.B. Holzer, S. Jensen, V. Kain, D. Küchler, A.M. Lombardi, A.I. Michet, M. O'Neil, S. Pasinelli, R. Scrivens, R. Steerenberg, G. Tranquille
CERN, Geneva, Switzerland

The renewed availability of heavy ions at CERN for the needs of the LHC programme has triggered the interest of the fixed-target community. The project, which involves sending several species of primary ions at various energies to the North Area of the Super Proton Synchrotron, has now entered its operational phase. The first argon run, with momenta ranging from 13 AGeV/c to 150 AGeV/c, took place from February 2015 to April 2015. This paper presents the status of the project, the performance achieved thus far and an outlook on future plans.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR027

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TUPOR028

Excitation of Longitudinal Coupled-bunch Oscillations with the Wide-band Cavity in the CERN PS

1724

L. Ventura, M. Migliorati
INFN-Roma1, Rome, Italy
H. Damerau, M. Migliorati, G. Sterbini
CERN, Geneva, Switzerland
M. Migliorati
University of Rome "La Sapienza", Rome, Italy

Longitudinal coupled-bunch oscillations in the CERN Proton Synchrotron have been studied in the past years and they have been recognized as one of the major challenges to reach the high brightness beam required by the High Luminosity LHC project. In the frame of the LHC Injectors Upgrade project in 2014 a new wide-band Finemet cavity has been installed in the Proton Synchrotron as a part of the coupled-bunch feedback system. To explore the functionality of the Finemet cavity during 2015 a dedicated measurement campaign has been performed. Coupled-bunch oscillations have been excited with the cavity around each harmonic of the revolution frequency with both a uniform and nominal filling pattern. In the following the measurements procedure and results are presented.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMY039

RF Synchronization and Distribution for AWAKE at CERN

3743

H. Damerau, D. Barrientos, T. Bohl, A.C. Butterworth, S. Döbert, W. Höfle, J.C. Molendijk, S.F. Rey, U. Wehrle
CERN, Geneva, Switzerland
J.T. Moody, P. Muggli
MPI-P, München, Germany

The Advanced Wakefield Experiment at CERN (AWAKE) requires two particle beams and a high power laser pulse to arrive simultaneously in a rubidium plasma cell. A proton bunch from the SPS extracted about once every 30 seconds must be synchronised with the AWAKE laser and the electron beam pulsing at a repetition rate of 10 Hz. The latter is directly generated using a photocathode triggered by part of the laser light, but the exact time of arrival in the plasma cell still depends on the phase of the RF in the accelerating structure. Each beam requires RF signals at characteristic frequencies: 6 GHz, 88.2 MHz and 10 Hz for the synchronisation of the laser pulse, 400.8 MHz and 8.7 kHz for the SPS, as well as 3 GHz to drive the accelerating structure of the electron beam. A low-level RF system has been designed to generate all signals derived from a common reference. Additionally precision triggers, synchronous with the arrival of the beams, will be distributed to beam instrumentation equipment. To suppress delay drifts of the several kilometer long optical fibres between AWAKE and the SPS RF systems, a compensated fibre link is being developed.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY039

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)