IPAC2013 - List of Authors (Levinsen, Y.I.)

Paper	Title	Page
MOPME076	Determination of Octupole and Sextupole Polarities in the LHC	655
	M.J. McAteer, Y.I. Levinsen, E.H. Maclean, T. Persson, P. Skowroński, R.J. Steinhagen, R. Tomás CERN, Geneva, Switzerland
	We report the results of measurements to verify the polarity of the LHC’s lattice focusing and defocusing octupoles (MOF and MOD), spool piece octupole correctors (MCO), arc skew sextupole correctors (MSS), and interaction region sextupoles (MCSX and MCSSX). Octupole polarities were determined by measuring the change to second order chromaticity when a magnet family was trimmed. The MSS skew sextupole corrector polarities were checked by measuring the change to chromatic coupling when a magnet family was trimmed. The polarities of the MCSSX skew sextupoles in IR 1 and the MCSX normal sextupoles in IR 5 were checked by measuring the tune shift due to a magnet trim. Comparison of measurements with model predictions indicates that the polarities of the octupoles and the IR sextupoles are correct, and the polarities of the MSS skew sextupole correctors are reversed.

MOPWO028	Recent Developments and Future Plans for SixTrack	948
	R. De Maria, R. Bruce, R. Calaga, L. Deniau, M. Fjellstrom, M. Giovannozzi, L. Lari, Y.I. Levinsen, E. McIntosh, A. Mereghetti, D. Pastor Sinuela, S. Redaelli, H. Renshall, A. Rossi, F. Schmidt, R. Tomás, V. Vlachoudis CERN, Geneva, Switzerland R. Appleby, D.R. Brett UMAN, Manchester, United Kingdom D. Banfi, J. Barranco EPFL, Lausanne, Switzerland B. Dalena CEA/IRFU, Gif-sur-Yvette, France L. Lari IFIC, Valencia, Spain V. Previtali Fermilab, Batavia, USA G. Robert-Demolaize BNL, Upton, Long Island, New York, USA
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. SixTrack is a symplectic 6D tracking code routinely used to simulate single particle trajectories in high energy circular machines like the LHC and RHIC. The paper presents the developments recently implemented and those foreseen for extending the physics models: exact Hamiltonian, different ions and charge states, RF multipoles, non-linear fringe fields, Taylor maps, e-lenses, ion scattering. Moreover new functionalities are also added like variable number of tracked particles, time dependent strengths, GPU computations with a refactoring of the core structure. The developments will benefit studies on the LHC and SPS, for collimation efficiency, ion operations, failure scenarios and HL-LHC design.

MOPWO053	Evolution of the Tracking Code PLACET	1014
	A. Latina, Y.I. Levinsen, D. Schulte CERN, Geneva, Switzerland J. Snuverink JAI, Egham, Surrey, United Kingdom
	The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. A major restructuring of its core has resulted in an improvement in its modularity, with some immediate advantages: its tracking core, which is one of the fastest available for this kind of simulations, is now interfaced toward three different scripting languages to offer great simulation capabilities: Tcl/Tk, Octave and Python. These three languages provide access to a vast library of scientific tools, mechanisms for parallel computing, and access to Java interfaces for control systems (such as that of CTF3). Also, new functionalities have been added: parallel tracking to exploit modern multicore CPUs, the possibility to track through the interaction region in presence of external magnetic fields (detector solenoid) and higher order imperfections in magnets. PLACET is currently used to simulate the CLIC Drive Beam, the CLIC Main Beam, CTF3, FACET at SLAC, and ATF2 at KEK.

TUPFI039	Optics Performance of the LHC During the 2012 Run	1433
	P. Skowroński, T. Bach, M. Giovannozzi, A. Langner, Y.I. Levinsen, E.H. Maclean, T. Persson, S. Redaelli, T. Risselada, M. Solfaroli Camillocci, R. Tomás, G. Vanbavinckhove CERN, Geneva, Switzerland M.J. McAteer The University of Texas at Austin, Austin, USA R. Miyamoto ESS, Lund, Sweden T. Persson Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden
	During 2012 the LHC was operating at 4TeV with beta star at ATLAS and CMS interaction points of 0.6m. During dedicated machine studies the nominal LHC optics was also setup with beta star of 0.4m. A huge effort was put into the optics commissioning leading to a record low peak beta-beating of around 7%. We describe the correction procedures and discuss the measurement results.

TUPFI041	Operating the LHC Off-momentum for p-Pb Collisions	1439
	R. Versteegen, R. Bruce, J.M. Jowett, A. Langner, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, T. Persson, S. Redaelli, B. Salvachua, P. Skowroński, M. Solfaroli Camillocci, R. Tomás, G. Valentino, J. Wenninger CERN, Geneva, Switzerland E.H. Maclean JAI, Oxford, United Kingdom M.J. McAteer The University of Texas at Austin, Austin, USA T. Persson Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden G. Valentino University of Malta, Information and Communication Technology, Msida, Malta S.M. White BNL, Upton, Long Island, New York, USA
	The first high-luminosity p-Pb run at the LHC took place in January-February 2013 at an energy of 4 Z TeV per beam. The RF frequency difference of proton and Pb is about 60 Hz for equal magnetic rigidities, which means that beams move slightly to off-momentum, non-central, orbits during physics when frequencies are locked together. The resulting optical perturbations ("beta-beating") restrict the available aperture and required a special correction. This was also the first operation of the LHC with low beta in all four experiments and required a specific collimation set up. Predictions from offline calculations of beta-beating correction are compared with measurements during the optics commissioning and collimator set up.

TUPME051	CLIC Final Focus System Alignment and Magnet Tolerances	1682
	J. Snuverink, J. Barranco, H. Garcia, Y.I. Levinsen, D. Schulte, R. Tomás CERN, Geneva, Switzerland
	The design requirements for the magnets in the Compact Linear Collider (CLIC) Final Focus System (FFS) are very stringent. In this paper the sensitivity for the misalignment and the magnetic imperfections for the different magnets in the FFS and the crab cavity are presented. Possible mitigation methods are discussed.

TUPWO048	Understanding the Tune, Coupling, and Chromaticity Dependence of the LHC on Landau Octupole Powering	1976
	E.H. Maclean, M. Giovannozzi, W. Herr, Y.I. Levinsen, G. Papotti, T. Persson, P. Skowroński, R. Tomás, J. Wenninger CERN, Geneva, Switzerland
	During the 2012 LHC run there were several observations of unexpectedly large shifts to the tune, chromaticity, and coupling which were correlated with changes in the powering of Landau octupoles (MO). Understanding the chromaticity dependence is of particular importance given it's influence on instabilities. This paper summarizes the observations and our attempts to-date to understand the relationship between Q, Q', c- and the MO powering.

TUPWO049	Automatic Correction of Betatron Coupling in the LHC using Injection Oscillations	1979
	T. Persson, T. Bach, D. Jacquet, V. Kain, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, P. Skowroński, R. Tomás, G. Vanbavinckhove CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.

Paper

Title

Page

Determination of Octupole and Sextupole Polarities in the LHC

655

M.J. McAteer, Y.I. Levinsen, E.H. Maclean, T. Persson, P. Skowroński, R.J. Steinhagen, R. Tomás
CERN, Geneva, Switzerland

We report the results of measurements to verify the polarity of the LHC’s lattice focusing and defocusing octupoles (MOF and MOD), spool piece octupole correctors (MCO), arc skew sextupole correctors (MSS), and interaction region sextupoles (MCSX and MCSSX). Octupole polarities were determined by measuring the change to second order chromaticity when a magnet family was trimmed. The MSS skew sextupole corrector polarities were checked by measuring the change to chromatic coupling when a magnet family was trimmed. The polarities of the MCSSX skew sextupoles in IR 1 and the MCSX normal sextupoles in IR 5 were checked by measuring the tune shift due to a magnet trim. Comparison of measurements with model predictions indicates that the polarities of the octupoles and the IR sextupoles are correct, and the polarities of the MSS skew sextupole correctors are reversed.

MOPWO028

Recent Developments and Future Plans for SixTrack

948

R. De Maria, R. Bruce, R. Calaga, L. Deniau, M. Fjellstrom, M. Giovannozzi, L. Lari, Y.I. Levinsen, E. McIntosh, A. Mereghetti, D. Pastor Sinuela, S. Redaelli, H. Renshall, A. Rossi, F. Schmidt, R. Tomás, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby, D.R. Brett
UMAN, Manchester, United Kingdom
D. Banfi, J. Barranco
EPFL, Lausanne, Switzerland
B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
L. Lari
IFIC, Valencia, Spain
V. Previtali
Fermilab, Batavia, USA
G. Robert-Demolaize
BNL, Upton, Long Island, New York, USA

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
SixTrack is a symplectic 6D tracking code routinely used to simulate single particle trajectories in high energy circular machines like the LHC and RHIC. The paper presents the developments recently implemented and those foreseen for extending the physics models: exact Hamiltonian, different ions and charge states, RF multipoles, non-linear fringe fields, Taylor maps, e-lenses, ion scattering. Moreover new functionalities are also added like variable number of tracked particles, time dependent strengths, GPU computations with a refactoring of the core structure. The developments will benefit studies on the LHC and SPS, for collimation efficiency, ion operations, failure scenarios and HL-LHC design.

MOPWO053

Evolution of the Tracking Code PLACET

1014

A. Latina, Y.I. Levinsen, D. Schulte
CERN, Geneva, Switzerland
J. Snuverink
JAI, Egham, Surrey, United Kingdom

The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. A major restructuring of its core has resulted in an improvement in its modularity, with some immediate advantages: its tracking core, which is one of the fastest available for this kind of simulations, is now interfaced toward three different scripting languages to offer great simulation capabilities: Tcl/Tk, Octave and Python. These three languages provide access to a vast library of scientific tools, mechanisms for parallel computing, and access to Java interfaces for control systems (such as that of CTF3). Also, new functionalities have been added: parallel tracking to exploit modern multicore CPUs, the possibility to track through the interaction region in presence of external magnetic fields (detector solenoid) and higher order imperfections in magnets. PLACET is currently used to simulate the CLIC Drive Beam, the CLIC Main Beam, CTF3, FACET at SLAC, and ATF2 at KEK.

TUPFI039

Optics Performance of the LHC During the 2012 Run

1433

P. Skowroński, T. Bach, M. Giovannozzi, A. Langner, Y.I. Levinsen, E.H. Maclean, T. Persson, S. Redaelli, T. Risselada, M. Solfaroli Camillocci, R. Tomás, G. Vanbavinckhove
CERN, Geneva, Switzerland
M.J. McAteer
The University of Texas at Austin, Austin, USA
R. Miyamoto
ESS, Lund, Sweden
T. Persson
Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden

During 2012 the LHC was operating at 4TeV with beta star at ATLAS and CMS interaction points of 0.6m. During dedicated machine studies the nominal LHC optics was also setup with beta star of 0.4m. A huge effort was put into the optics commissioning leading to a record low peak beta-beating of around 7%. We describe the correction procedures and discuss the measurement results.

TUPFI041

Operating the LHC Off-momentum for p-Pb Collisions

1439

R. Versteegen, R. Bruce, J.M. Jowett, A. Langner, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, T. Persson, S. Redaelli, B. Salvachua, P. Skowroński, M. Solfaroli Camillocci, R. Tomás, G. Valentino, J. Wenninger
CERN, Geneva, Switzerland
E.H. Maclean
JAI, Oxford, United Kingdom
M.J. McAteer
The University of Texas at Austin, Austin, USA
T. Persson
Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta
S.M. White
BNL, Upton, Long Island, New York, USA

The first high-luminosity p-Pb run at the LHC took place in January-February 2013 at an energy of 4 Z TeV per beam. The RF frequency difference of proton and Pb is about 60 Hz for equal magnetic rigidities, which means that beams move slightly to off-momentum, non-central, orbits during physics when frequencies are locked together. The resulting optical perturbations ("beta-beating") restrict the available aperture and required a special correction. This was also the first operation of the LHC with low beta in all four experiments and required a specific collimation set up. Predictions from offline calculations of beta-beating correction are compared with measurements during the optics commissioning and collimator set up.

TUPME051

CLIC Final Focus System Alignment and Magnet Tolerances

1682

J. Snuverink, J. Barranco, H. Garcia, Y.I. Levinsen, D. Schulte, R. Tomás
CERN, Geneva, Switzerland

The design requirements for the magnets in the Compact Linear Collider (CLIC) Final Focus System (FFS) are very stringent. In this paper the sensitivity for the misalignment and the magnetic imperfections for the different magnets in the FFS and the crab cavity are presented. Possible mitigation methods are discussed.

TUPWO048

Understanding the Tune, Coupling, and Chromaticity Dependence of the LHC on Landau Octupole Powering

1976

E.H. Maclean, M. Giovannozzi, W. Herr, Y.I. Levinsen, G. Papotti, T. Persson, P. Skowroński, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland

During the 2012 LHC run there were several observations of unexpectedly large shifts to the tune, chromaticity, and coupling which were correlated with changes in the powering of Landau octupoles (MO). Understanding the chromaticity dependence is of particular importance given it's influence on instabilities. This paper summarizes the observations and our attempts to-date to understand the relationship between Q, Q', c- and the MO powering.

TUPWO049

Automatic Correction of Betatron Coupling in the LHC using Injection Oscillations

1979

T. Persson, T. Bach, D. Jacquet, V. Kain, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, P. Skowroński, R. Tomás, G. Vanbavinckhove
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.