HB2016 - List of Authors (Rumolo, G.)

Paper

Title

Page

LHC Run 2: Results and Challenges

14

R. Bruce, G. Arduini, H. Bartosik, R. De Maria, M. Giovannozzi, G. Iadarola, J.M. Jowett, M. Lamont, A. Lechner, K.S.B. Li, D. Mirarchi, E. Métral, T. Pieloni, S. Redaelli, G. Rumolo, B. Salvant, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland

The first proton run of the LHC was very successful and resulted in important physics discoveries. It was followed by a two-year shutdown where a large number of improvements were carried out. In 2015, the LHC was restarted and this second run aims at further exploring the physics of the standard model and beyond at an increased beam energy. This article gives a review of the performance achieved so far and the limitations encountered, as well as the future challenges for the CERN accelerators to maximize the data delivered to the LHC experiments in Run 2. Furthermore, the status of the 2016 LHC run and commissioning is discussed.

Slides MOAM5P50 [9.283 MB]

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MOPR026

Space Charge Mitigation With Longitudinally Hollow Bunches

130

A. Oeftiger, S. Hancock, G. Rumolo
CERN, Geneva, Switzerland

Funding: CERN, Doctoral Studentship and EPFL, Doctorate
Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN's PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

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TUAM2X01

Measurement and Interpretation of Transverse Beam Instabilities in the CERN Large Hadron Collider (LHC) and Extrapolations to HL-LHC

254

E. Métral, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, G. Iadarola, K.S.B. Li, T. Pieloni, A. Romano, G. Rumolo, B. Salvant, M. Schenk, C. Tambasco
CERN, Geneva, Switzerland
J. Barranco
EPFL, Lausanne, Switzerland

Since the first transverse instability observed in 2010, many studies have been performed on both measurement and simulation sides and several lessons have been learned. In a machine like the LHC, not only all the mechanisms have to be understood separately, but the possible interplays between the different phenomena need to be analyzed in detail, including the beam-coupling impedance (with in particular all the necessary collimators to protect the machine but also new equipment such as crab cavities for HL-LHC), linear and nonlinear chromaticity, Landau octupoles (and other intrinsic nonlinearities), transverse damper, space charge, beam-beam (long-range and head-on), electron cloud, linear coupling strength, tune separation between the transverse planes, tune split between the two beams, transverse beam separation between the two beams, etc. This paper reviews all the transverse beam instabilities observed and simulated so far, the mitigation measures which have been put in place, the remaining questions and challenges and some recommendations for the future.

Slides TUAM2X01 [36.385 MB]

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TUAM4X01

Electron Cloud in the CERN Accelerator Complex

266

G. Rumolo, H. Bartosik, E. Belli, G. Iadarola, K.S.B. Li, L. Mether, A. Romano
CERN, Geneva, Switzerland
M. Schenk
EPFL, Lausanne, Switzerland

Operation with closely spaced bunched beams causes the build up of an Electron Cloud (EC) in both the LHC and the two last synchrotrons of its injector chain (PS and SPS). Pressure rise and beam instabilities are observed at the PS during the last stage of preparation of the LHC beams. The SPS was affected by coherent and incoherent emittance growth along the LHC bunch train over many years, before scrubbing has finally suppressed the EC in a large fraction of the machine. When the LHC started regular operation with 50 ns beams in 2011, EC phenomena appeared in the arcs during the early phases, and in the interaction regions with two beams all along the run. Operation with 25 ns beams (late 2012 and 2015), which is nominal for LHC, has been hampered by EC induced high heat load in the cold arcs, bunch dependent emittance growth and degraded beam lifetime. Dedicated and parasitic machine scrubbing is presently the weapon used at the LHC to combat EC in this mode of operation. This talk summarises the EC experience in the CERN machines (PS, SPS, LHC) and highlight the dangers for future operation with more intense beams as well as the strategies to mitigate or suppress the effect.

Slides TUAM4X01 [9.785 MB]

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TUPM4X01

LHC Injectors Upgrade for the HL-LHC

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

The goal of the HL-LHC is to increase the LHC peak nominal Luminosity by a factor of seven in order to provide more accurate measurements of new particles and enable observation of rare processes that occur below the current sensitivity level. Achieving this target requires to double the beam intensity and reduce the emittance by 40%. All the LHC injectors, from the LINAC to the Super Proton Synchrotron (SPS) including the heavy ion chain, have to be improved to reliably supply such high brightness beams to the HL-LHC. The upgrade campaign will be completed during the Second Long Shutdown (LS2) in 2019-2020. The performance objectives and the status of this challenging program is presented.

Slides TUPM4X01 [10.021 MB]

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WEAM3X01

Code Development for Collective Effects

362

K.S.B. Li, H. Bartosik, G. Iadarola, A. Oeftiger, A. Passarelli, A. Romano, G. Rumolo, M. Schenk
CERN, Geneva, Switzerland
S. Hegglin
ETH, Zurich, Switzerland
A. Oeftiger, M. Schenk
EPFL, Lausanne, Switzerland

The presentation will cover approaches and strategies of modeling and implementing collective effects in modern simulation codes. We will review some of the general approaches to numerically model collective beam dynamics in circular accelerators. We will then look into modern ways of implementing collective effects with a focus on plainness, modularity and flexibility, using the example of the PyHEADTAIL framework, and highlight some of the advantages and drawbacks emerging from this method. To ameliorate one of the main drawbacks, namely a potential loss of performance compared to the classical fully compiled codes, several options for speed improvements will be mentioned and discussed. Finally some examples and application will be shown together with future plans and perspectives.

Slides WEAM3X01 [65.643 MB]

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WEAM4X01

Numerical Modeling of Fast Beam Ion Instabilities

368

L. Mether, G. Iadarola, G. Rumolo
CERN, Geneva, Switzerland

The fast beam ion instability may pose a risk to the operation of future electron accelerators with beams of high intensity and small emittances, including several structures of the proposed CLIC accelerator complex. Numerical models can be used to identify necessary vacuum specifications to suppress the instability, as well as requirements for a possible feedback system. Vacuum requirements imposed by the instability have previously been estimated for linear CLIC structures, using the strong-strong macroparticle simulation tool FASTION. Currently, efforts are being made to improve the simulation tools, and allow for equivalent studies of circular structures, such as the CLIC damping rings, on a multi-turn scale. In this contribution, we review the recent code developments, and present first simulation results.

Slides WEAM4X01 [3.379 MB]

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WEAM5X01

Beam-Dynamics Issues in the FCC

373

F. Zimmermann, W. Bartmann, M. Benedikt, M.I. Besana, R. Bruce, O.S. Brüning, X. Buffat, F. Burkart, H. Burkhardt, S. Calatroni, F. Cerutti, S.D. Fartoukh, M. Fiascaris, C. Garion, B. Goddard, B.J. Holzer, W. Höfle, J.M. Jowett, R. Kersevan, R. Martin, L. Mether, A. Milanese, T. Pieloni, S. Redaelli, G. Rumolo, B. Salvant, M. Schaumann, D. Schulte, E.N. Shaposhnikova, L.S. Stoel, C. Tambasco, R. Tomás, D. Tommasini
CERN, Geneva, Switzerland
J.L. Abelleira, E. Cruz Alaniz, A. Seryi
JAI, Oxford, United Kingdom
R.B. Appleby
UMAN, Manchester, United Kingdom
P. Bambade, A. Faus-Golfe, J. Molson
LAL, Orsay, France
J. Barranco
EPFL, Lausanne, Switzerland
J.-L. Biarrotte, A. Lachaize
IPN, Orsay, France
O. Boine-Frankenheim, U. Niedermayer
TEMF, TU Darmstadt, Darmstadt, Germany
M. Boscolo, F. Collamati, A. Drago
INFN/LNF, Frascati (Roma), Italy
A. Chancé
CEA, Gif-sur-Yvette, France
B. Dalena, J. Payet
CEA/IRFU, Gif-sur-Yvette, France
J.D. Fox, G. Stupakov
SLAC, Menlo Park, California, USA
G. Guillermo Cantón
CINVESTAV, Mérida, Mexico
S. Khan, B. Riemann
DELTA, Dortmund, Germany
V. Kornilov
GSI, Darmstadt, Germany
T.M. Mitsuhashi, K. Ohmi
KEK, Ibaraki, Japan

Funding: European Commission under the Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305. Also by the German BMBF.
The international Future Circular Collider (FCC) study is designing hadron, lepton and lepton-hadron colliders based on a new 100 km tunnel in the Geneva region. The main focus and ultimate goal of the study are high-luminosity proton-proton collisions at a centre-of-mass energy of 100 TeV, using 16 T Nb3Sn dipole magnets. Specific FCC beam dynamics issues are related to the large circumference, the high brightness - made available by radiation damping -, the small geometric emittance, unprecedented collision energy and luminosity, the huge amount of energy stored in the beam, large synchrotron radiation power, plus the injection scenarios. In addition to the FCC-hh proper, also a High-Energy LHC (HE-LHC) is being explored, using the FCC-hh magnet technology in the existing LHC tunnel, which can yield a centre-of-mass energy around 25 TeV.

Slides WEAM5X01 [10.402 MB]

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Paper	Title	Page
MOAM5P50	LHC Run 2: Results and Challenges	14
	R. Bruce, G. Arduini, H. Bartosik, R. De Maria, M. Giovannozzi, G. Iadarola, J.M. Jowett, M. Lamont, A. Lechner, K.S.B. Li, D. Mirarchi, E. Métral, T. Pieloni, S. Redaelli, G. Rumolo, B. Salvant, R. Tomás, J. Wenninger CERN, Geneva, Switzerland
	The first proton run of the LHC was very successful and resulted in important physics discoveries. It was followed by a two-year shutdown where a large number of improvements were carried out. In 2015, the LHC was restarted and this second run aims at further exploring the physics of the standard model and beyond at an increased beam energy. This article gives a review of the performance achieved so far and the limitations encountered, as well as the future challenges for the CERN accelerators to maximize the data delivered to the LHC experiments in Run 2. Furthermore, the status of the 2016 LHC run and commissioning is discussed.
	Slides MOAM5P50 [9.283 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPR026	Space Charge Mitigation With Longitudinally Hollow Bunches	130
	A. Oeftiger, S. Hancock, G. Rumolo CERN, Geneva, Switzerland
	Funding: CERN, Doctoral Studentship and EPFL, Doctorate Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN's PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUAM2X01	Measurement and Interpretation of Transverse Beam Instabilities in the CERN Large Hadron Collider (LHC) and Extrapolations to HL-LHC	254
	E. Métral, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, G. Iadarola, K.S.B. Li, T. Pieloni, A. Romano, G. Rumolo, B. Salvant, M. Schenk, C. Tambasco CERN, Geneva, Switzerland J. Barranco EPFL, Lausanne, Switzerland
	Since the first transverse instability observed in 2010, many studies have been performed on both measurement and simulation sides and several lessons have been learned. In a machine like the LHC, not only all the mechanisms have to be understood separately, but the possible interplays between the different phenomena need to be analyzed in detail, including the beam-coupling impedance (with in particular all the necessary collimators to protect the machine but also new equipment such as crab cavities for HL-LHC), linear and nonlinear chromaticity, Landau octupoles (and other intrinsic nonlinearities), transverse damper, space charge, beam-beam (long-range and head-on), electron cloud, linear coupling strength, tune separation between the transverse planes, tune split between the two beams, transverse beam separation between the two beams, etc. This paper reviews all the transverse beam instabilities observed and simulated so far, the mitigation measures which have been put in place, the remaining questions and challenges and some recommendations for the future.
	Slides TUAM2X01 [36.385 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUAM4X01	Electron Cloud in the CERN Accelerator Complex	266
	G. Rumolo, H. Bartosik, E. Belli, G. Iadarola, K.S.B. Li, L. Mether, A. Romano CERN, Geneva, Switzerland M. Schenk EPFL, Lausanne, Switzerland
	Operation with closely spaced bunched beams causes the build up of an Electron Cloud (EC) in both the LHC and the two last synchrotrons of its injector chain (PS and SPS). Pressure rise and beam instabilities are observed at the PS during the last stage of preparation of the LHC beams. The SPS was affected by coherent and incoherent emittance growth along the LHC bunch train over many years, before scrubbing has finally suppressed the EC in a large fraction of the machine. When the LHC started regular operation with 50 ns beams in 2011, EC phenomena appeared in the arcs during the early phases, and in the interaction regions with two beams all along the run. Operation with 25 ns beams (late 2012 and 2015), which is nominal for LHC, has been hampered by EC induced high heat load in the cold arcs, bunch dependent emittance growth and degraded beam lifetime. Dedicated and parasitic machine scrubbing is presently the weapon used at the LHC to combat EC in this mode of operation. This talk summarises the EC experience in the CERN machines (PS, SPS, LHC) and highlight the dangers for future operation with more intense beams as well as the strategies to mitigate or suppress the effect.
	Slides TUAM4X01 [9.785 MB]
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TUPM4X01	LHC Injectors Upgrade for the HL-LHC
	C. Bracco, J. Coupard, H. Damerau, A. Funken, B. Goddard, K. Hanke, A.M. Lombardi, D. Manglunki, S. Mataguez, M. Meddahi, B. Mikulec, G. Rumolo, R. Scrivens, E.N. Shaposhnikova, M. Vretenar CERN, Geneva, Switzerland
	The goal of the HL-LHC is to increase the LHC peak nominal Luminosity by a factor of seven in order to provide more accurate measurements of new particles and enable observation of rare processes that occur below the current sensitivity level. Achieving this target requires to double the beam intensity and reduce the emittance by 40%. All the LHC injectors, from the LINAC to the Super Proton Synchrotron (SPS) including the heavy ion chain, have to be improved to reliably supply such high brightness beams to the HL-LHC. The upgrade campaign will be completed during the Second Long Shutdown (LS2) in 2019-2020. The performance objectives and the status of this challenging program is presented.
	Slides TUPM4X01 [10.021 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEAM3X01	Code Development for Collective Effects	362
	K.S.B. Li, H. Bartosik, G. Iadarola, A. Oeftiger, A. Passarelli, A. Romano, G. Rumolo, M. Schenk CERN, Geneva, Switzerland S. Hegglin ETH, Zurich, Switzerland A. Oeftiger, M. Schenk EPFL, Lausanne, Switzerland
	The presentation will cover approaches and strategies of modeling and implementing collective effects in modern simulation codes. We will review some of the general approaches to numerically model collective beam dynamics in circular accelerators. We will then look into modern ways of implementing collective effects with a focus on plainness, modularity and flexibility, using the example of the PyHEADTAIL framework, and highlight some of the advantages and drawbacks emerging from this method. To ameliorate one of the main drawbacks, namely a potential loss of performance compared to the classical fully compiled codes, several options for speed improvements will be mentioned and discussed. Finally some examples and application will be shown together with future plans and perspectives.
	Slides WEAM3X01 [65.643 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEAM4X01	Numerical Modeling of Fast Beam Ion Instabilities	368
	L. Mether, G. Iadarola, G. Rumolo CERN, Geneva, Switzerland
	The fast beam ion instability may pose a risk to the operation of future electron accelerators with beams of high intensity and small emittances, including several structures of the proposed CLIC accelerator complex. Numerical models can be used to identify necessary vacuum specifications to suppress the instability, as well as requirements for a possible feedback system. Vacuum requirements imposed by the instability have previously been estimated for linear CLIC structures, using the strong-strong macroparticle simulation tool FASTION. Currently, efforts are being made to improve the simulation tools, and allow for equivalent studies of circular structures, such as the CLIC damping rings, on a multi-turn scale. In this contribution, we review the recent code developments, and present first simulation results.
	Slides WEAM4X01 [3.379 MB]
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WEAM5X01	Beam-Dynamics Issues in the FCC	373
	F. Zimmermann, W. Bartmann, M. Benedikt, M.I. Besana, R. Bruce, O.S. Brüning, X. Buffat, F. Burkart, H. Burkhardt, S. Calatroni, F. Cerutti, S.D. Fartoukh, M. Fiascaris, C. Garion, B. Goddard, B.J. Holzer, W. Höfle, J.M. Jowett, R. Kersevan, R. Martin, L. Mether, A. Milanese, T. Pieloni, S. Redaelli, G. Rumolo, B. Salvant, M. Schaumann, D. Schulte, E.N. Shaposhnikova, L.S. Stoel, C. Tambasco, R. Tomás, D. Tommasini CERN, Geneva, Switzerland J.L. Abelleira, E. Cruz Alaniz, A. Seryi JAI, Oxford, United Kingdom R.B. Appleby UMAN, Manchester, United Kingdom P. Bambade, A. Faus-Golfe, J. Molson LAL, Orsay, France J. Barranco EPFL, Lausanne, Switzerland J.-L. Biarrotte, A. Lachaize IPN, Orsay, France O. Boine-Frankenheim, U. Niedermayer TEMF, TU Darmstadt, Darmstadt, Germany M. Boscolo, F. Collamati, A. Drago INFN/LNF, Frascati (Roma), Italy A. Chancé CEA, Gif-sur-Yvette, France B. Dalena, J. Payet CEA/IRFU, Gif-sur-Yvette, France J.D. Fox, G. Stupakov SLAC, Menlo Park, California, USA G. Guillermo Cantón CINVESTAV, Mérida, Mexico S. Khan, B. Riemann DELTA, Dortmund, Germany V. Kornilov GSI, Darmstadt, Germany T.M. Mitsuhashi, K. Ohmi KEK, Ibaraki, Japan
	Funding: European Commission under the Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305. Also by the German BMBF. The international Future Circular Collider (FCC) study is designing hadron, lepton and lepton-hadron colliders based on a new 100 km tunnel in the Geneva region. The main focus and ultimate goal of the study are high-luminosity proton-proton collisions at a centre-of-mass energy of 100 TeV, using 16 T Nb3Sn dipole magnets. Specific FCC beam dynamics issues are related to the large circumference, the high brightness - made available by radiation damping -, the small geometric emittance, unprecedented collision energy and luminosity, the huge amount of energy stored in the beam, large synchrotron radiation power, plus the injection scenarios. In addition to the FCC-hh proper, also a High-Energy LHC (HE-LHC) is being explored, using the FCC-hh magnet technology in the existing LHC tunnel, which can yield a centre-of-mass energy around 25 TeV.
	Slides WEAM5X01 [10.402 MB]
Export •	reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)