IPAC2016 - List of Authors (Höfle, W.)

Paper	Title	Page
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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TUPMW011	Current Status of Instability Threshold Measurements in the LHC at 6.5 TeV	1434
	L.R. Carver, J. Barranco, N. Biancacci, X. Buffat, W. Höfle, G. Kotzian, T. Lefèvre, T.E. Levens, E. Métral, T. Pieloni, B. Salvant, C. Tambasco CERN, Geneva, Switzerland N. Wang IHEP, Beijing, People's Republic of China M. Zobov INFN/LNF, Frascati (Roma), Italy
	Throughout 2015, many measurements of the minimum stabilizing octupole current required to prevent coherent transverse instabilities have been performed. These measurements allow the LHC impedance model at flat top to be verified and give good indicators of future performance and limitations. The results are summarized here, and compared to predictions from the simulation code DELPHI.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW011
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TUPMW027	The 2015 Heavy-Ion Run of the LHC	1493
	J.M. Jowett, R. Alemany-Fernandez, R. Bruce, M. Giovannozzi, P.D. Hermes, W. Höfle, M. Lamont, T. Mertens, S. Redaelli, M. Schaumann, J.A. Uythoven, J. Wenninger CERN, Geneva, Switzerland
	In late 2015 the LHC collided lead nuclei at a beam energy of 6.37 Z TeV, chosen to match the 5.02 TeV per colliding nucleon pair of the p-Pb collision run in 2013. In so doing, it surpassed its design luminosity by a factor of 2. Besides the higher energy, the operational configuration had a number of new features with respect to the previous Pb-Pb run at 3.5 Z TeV in 2011; unusual bunch patterns providing collisions in the LHCb experiment for the first time, luminosity levelling and sharing requirements, a vertical displacement of the interaction point in the ALICE experiment, and operation closer to magnet quench limits with mitigation measures. We present a summary of the commissioning and operation and what has been learned in view of future heavy-ion operation at higher luminosity.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW027
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WEOCA01	Operation of the LHC with Protons at High Luminosity and High Energy	2066
	G. Papotti, M. Albert, R. Alemany-Fernandez, G.E. Crockford, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, D. Jacquet, M. Lamont, D. Nisbet, L. Normann, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli Camillocci, R. Suykerbuyk, J.A. Uythoven, J. Wenninger CERN, Geneva, Switzerland
	In 2015 the Large Hadron Collider (LHC) entered the first year in its second long Run, after a 2-year shutdown that prepared it for high energy. The first two months of beam operation were dedicated to setting up the nominal cycle for proton-proton operation at 6.5 TeV/beam, and culminated with the first physics with 3 nominal bunches/ring at 13 TeV CoM on 3 June. The year continued with a stepwise intensity ramp up that allowed reaching 2244 bunches/ring for a peak luminosity of ~5·10³³ cm^-2s⁻¹ and a total of just above 4 fb-1 delivered to the high luminosity experiments. Beam operation was shaped by the high intensity effects, e.g. electron cloud and macroparticle-induced fast losses (UFOs), which on a few occasions caused the first beam induced quenches at high energy. This paper describes the operational experience with high intensity and high energy at the LHC, together with the issues that had to be tackled along the way.
	Slides WEOCA01 [4.013 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOCA01
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WEPMW028	First Attempts at using Active Halo Control at the LHC	2486
	J.F. Wagner Goethe Universität Frankfurt, Frankfurt am Main, Germany R. Bruce, H. Garcia Morales, W. Höfle, G. Kotzian, R. Kwee-Hinzmann, A. Langner, A. Mereghetti, E. Quaranta, S. Redaelli, A. Rossi, B. Salvachua, R. Tomás, G. Valentino, D. Valuch, J.F. Wagner CERN, Geneva, Switzerland G. Stancari Fermilab, Batavia, Illinois, USA
	Funding: Research supported by the High Luminosity LHC project. The beam halo population is a non-negligible factor for the performance of the LHC collimation system and the machine protection. In particular this could become crucial for aiming at stored beam energies of 700 MJ in the High Luminosity (HL-LHC) project, in order to avoid beam dumps caused by orbit jitter and to ensure safety during a crab cavity failure. Therefore several techniques to safely deplete the halo, i.e. active halo control, are under development. In a first attempt a novel way for safe halo depletion was tested with particle narrow-band excitation employing the LHC Transverse Damper (ADT). At an energy of 450 GeV a bunch selective beam tail scraping without affecting the core distribution was attempted. This paper presents the first measurement results, as well as a simple simulation to model the underlying dynamics.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW028
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WEPOR010	Recent Upgrades to the CERN SPS Wideband Intra-bunch Transverse Feedback Processor	2687
	J.E. Dusatko, J.D. Fox, C.H. Rivetta SLAC, Menlo Park, California, USA W. Höfle CERN, Geneva, Switzerland O. Turgut Stanford University, Stanford, California, USA
	In support of the CERN High Luminosity LHC (HL-LHC) upgrade program, a research and development effort has been underway to understand and develop feedback control techniques for mitigating transverse intra-bunch instabilities in the SPS driven by electron cloud and TMCI effects. These effects could be a limiting factor to overall machine performance. A result of this effort has been the development of a very wide band transverse feedback demonstration system. This system has been used for the last several years in machine development studies where we have demonstrated single-bunch stability control of low order intra-bunch modes. In continuation of these efforts, recent upgrades have been performed in all stages of the system, including the feedback processor itself. This paper discusses the upgrades specific to it, including the ability to process multiple proton bunches in the SPS; and also highlights future directions in the development effort.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR010
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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

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

Export •

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

TUPMW011

Current Status of Instability Threshold Measurements in the LHC at 6.5 TeV

1434

L.R. Carver, J. Barranco, N. Biancacci, X. Buffat, W. Höfle, G. Kotzian, T. Lefèvre, T.E. Levens, E. Métral, T. Pieloni, B. Salvant, C. Tambasco
CERN, Geneva, Switzerland
N. Wang
IHEP, Beijing, People's Republic of China
M. Zobov
INFN/LNF, Frascati (Roma), Italy

Throughout 2015, many measurements of the minimum stabilizing octupole current required to prevent coherent transverse instabilities have been performed. These measurements allow the LHC impedance model at flat top to be verified and give good indicators of future performance and limitations. The results are summarized here, and compared to predictions from the simulation code DELPHI.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW011

Export •

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

TUPMW027

The 2015 Heavy-Ion Run of the LHC

1493

J.M. Jowett, R. Alemany-Fernandez, R. Bruce, M. Giovannozzi, P.D. Hermes, W. Höfle, M. Lamont, T. Mertens, S. Redaelli, M. Schaumann, J.A. Uythoven, J. Wenninger
CERN, Geneva, Switzerland

In late 2015 the LHC collided lead nuclei at a beam energy of 6.37 Z TeV, chosen to match the 5.02 TeV per colliding nucleon pair of the p-Pb collision run in 2013. In so doing, it surpassed its design luminosity by a factor of 2. Besides the higher energy, the operational configuration had a number of new features with respect to the previous Pb-Pb run at 3.5 Z TeV in 2011; unusual bunch patterns providing collisions in the LHCb experiment for the first time, luminosity levelling and sharing requirements, a vertical displacement of the interaction point in the ALICE experiment, and operation closer to magnet quench limits with mitigation measures. We present a summary of the commissioning and operation and what has been learned in view of future heavy-ion operation at higher luminosity.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW027

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WEOCA01

Operation of the LHC with Protons at High Luminosity and High Energy

2066

G. Papotti, M. Albert, R. Alemany-Fernandez, G.E. Crockford, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, D. Jacquet, M. Lamont, D. Nisbet, L. Normann, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli Camillocci, R. Suykerbuyk, J.A. Uythoven, J. Wenninger
CERN, Geneva, Switzerland

In 2015 the Large Hadron Collider (LHC) entered the first year in its second long Run, after a 2-year shutdown that prepared it for high energy. The first two months of beam operation were dedicated to setting up the nominal cycle for proton-proton operation at 6.5 TeV/beam, and culminated with the first physics with 3 nominal bunches/ring at 13 TeV CoM on 3 June. The year continued with a stepwise intensity ramp up that allowed reaching 2244 bunches/ring for a peak luminosity of ~5·10³³ cm^-2s⁻¹ and a total of just above 4 fb-1 delivered to the high luminosity experiments. Beam operation was shaped by the high intensity effects, e.g. electron cloud and macroparticle-induced fast losses (UFOs), which on a few occasions caused the first beam induced quenches at high energy. This paper describes the operational experience with high intensity and high energy at the LHC, together with the issues that had to be tackled along the way.

Slides WEOCA01 [4.013 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOCA01

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WEPMW028

First Attempts at using Active Halo Control at the LHC

2486

J.F. Wagner
Goethe Universität Frankfurt, Frankfurt am Main, Germany
R. Bruce, H. Garcia Morales, W. Höfle, G. Kotzian, R. Kwee-Hinzmann, A. Langner, A. Mereghetti, E. Quaranta, S. Redaelli, A. Rossi, B. Salvachua, R. Tomás, G. Valentino, D. Valuch, J.F. Wagner
CERN, Geneva, Switzerland
G. Stancari
Fermilab, Batavia, Illinois, USA

Funding: Research supported by the High Luminosity LHC project.
The beam halo population is a non-negligible factor for the performance of the LHC collimation system and the machine protection. In particular this could become crucial for aiming at stored beam energies of 700 MJ in the High Luminosity (HL-LHC) project, in order to avoid beam dumps caused by orbit jitter and to ensure safety during a crab cavity failure. Therefore several techniques to safely deplete the halo, i.e. active halo control, are under development. In a first attempt a novel way for safe halo depletion was tested with particle narrow-band excitation employing the LHC Transverse Damper (ADT). At an energy of 450 GeV a bunch selective beam tail scraping without affecting the core distribution was attempted. This paper presents the first measurement results, as well as a simple simulation to model the underlying dynamics.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW028

Export •

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

WEPOR010

Recent Upgrades to the CERN SPS Wideband Intra-bunch Transverse Feedback Processor

2687

J.E. Dusatko, J.D. Fox, C.H. Rivetta
SLAC, Menlo Park, California, USA
W. Höfle
CERN, Geneva, Switzerland
O. Turgut
Stanford University, Stanford, California, USA

In support of the CERN High Luminosity LHC (HL-LHC) upgrade program, a research and development effort has been underway to understand and develop feedback control techniques for mitigating transverse intra-bunch instabilities in the SPS driven by electron cloud and TMCI effects. These effects could be a limiting factor to overall machine performance. A result of this effort has been the development of a very wide band transverse feedback demonstration system. This system has been used for the last several years in machine development studies where we have demonstrated single-bunch stability control of low order intra-bunch modes. In continuation of these efforts, recent upgrades have been performed in all stages of the system, including the feedback processor itself. This paper discusses the upgrades specific to it, including the ability to process multiple proton bunches in the SPS; and also highlights future directions in the development effort.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR010

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

Export •

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