IPAC2016 - List of Authors (Maclean, E.H.)

Paper	Title	Page
MOPMR029	Experience with DOROS BPMs for Coupling Measurement and Correction	303
	T. Persson, J.M. Coello de Portugal, A. Garcia-Tabares, M. Gąsior, A. Langner, T. Lefèvre, E.H. Maclean, L. Malina, J. Olexa, P.K. Skowroński, R. Tomás CERN, Geneva, Switzerland J. Olexa STU, Bratislava, Slovak Republic
	The Diode ORbit and OScillation System (DOROS) system is designed to provide accurate measurements of the beam position in the LHC. The oscillation part of the system, which is able to provide turn-by-turn data, is used to measure the transverse coupling. Since the system provides high resolution measurements for many turns only small excitations are needed to accurately measure the transverse coupling. In this article we present the performance the system to measure coupling and compare it to the BPMs not equipped with this system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR029
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THPMB041	Optics-measurement-based BPM Calibration	3328
SUPSS047	use link to see paper's listing under its alternate paper code
	A. Garcia-Tabares, F.S. Carlier, J.M. Coello de Portugal, A. Langner, E.H. Maclean, L. Malina, T. Persson, P.K. Skowroński, M. Solfaroli Camillocci, R. Tomás CERN, Geneva, Switzerland
	The LHC beta functions (β) can be measured using the phase or the amplitude of betatron oscillations obtained with beam position monitors (BPMs). Using the amplitude information results in a β measurement affected by BPM calibration. This work aims at calibrating BPMs using optics measurements. For this, βs from amplitude and phase and normalized dispersion obtained from many different measurements in 2015 with different optics and corrections are analyzed. Simulations are also performed to support the analyses.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB041
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THPMB044	Limitations on Optics Measurements in the LHC	3339
	P.K. Skowroński, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, M. McAteer, T. Persson, R. Tomás CERN, Geneva, Switzerland A. Langner University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany L. Malina University of Oslo, Oslo, Norway
	In preparation of the optics commissioning at an energy of 6.5 TeV, many improvements have been done to cope with the expected reduced signal to noise ratio due to lowered bunch intensities imposed by machine protection considerations. This included, among others, an increase of the flat top duration of the AC dipole excitations, which allowed to use more turn-by-turn data for the analysis. The longer data acquisition revealed slow drifts of the optics, which limited the increased measurement precision. Furthermore, we will present how orbit drifts influenced dispersion measurements and, as a consequence, posed another limitation for the optics correction. In this paper we will discuss the implications of these observations for the measurement and correction of the optics.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB044
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THPMR037	Observations of Resonance Driving Terms in the LHC during Runs I and II	3468
	F.S. Carlier, J.M. Coello de Portugal, E.H. Maclean, T. Persson, R. Tomás CERN, Geneva, Switzerland
	Future operations of the LHC will require a good understanding of the nonlinear beam dynamics. In 2012, turn-by-turn measurements of large diagonal betatron excitations in LHC Beam 2 were taken at injection energy. Spectral analysis of these measurements shows an anomalous octupolar spectral line at frequency -Qx-2Qy in the horizontal motion. The presence of this spectral line, as well as other lines, was confirmed by measurements taken for LHC Beam 1 and Beam 2 during the commissioning in 2015. We take a close look at the various spectral lines appearing in the LHC transverse motion in order to improve the LHC nonlinear model.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR037
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THPMR038	Non-Linear Errors in the Experimental Insertions of the LHC	3472
	E.H. Maclean, F.S. Carlier, M. Giovannozzi, A. Langner, S. Mönig, T. Persson, P.K. Skowroński, R. Tomás CERN, Geneva, Switzerland
	Correction of nonlinear magnetic errors in low-β insertions can be of critical significance for the operation of a collider. This is expected to be of particular relevance to LHC Run II and the HL-LHC upgrade, as well as to future colliders such as the FCC. Current correction strategies for these accelerators have assumed it will be possible to calculate optimized local corrections through the insertions using a magnetic model of the errors. To test this assumption the nonlinear errors in the LHC experimental insertions have been examined via feed-down and amplitude detuning. It will be shown that while in some cases the magnetic measurements provide a sufficient description of the errors, in others large discrepancies exist which will require beam-based correction techniques.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR038
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THPMR039	Commissioning of Non-linear Optics in the LHC at Injection Energy	3476
	E.H. Maclean, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, A. Langner, L. Malina, T. Persson, P.K. Skowroński, R. Tomás CERN, Geneva, Switzerland
	Commissioning of the nonlinear optics at injection in the LHC was carried out for the first time in 2015 via beam-based methods. Building upon studies performed during Run I, corrections to the nonlinear chromaticity and detuning with amplitude were obtained. These corrections were observed to reduce beam-loss during measurement of linear optics.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR039
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THPMR040	Local Optics Corrections in the HL-LHC IR	3480
SUPSS046	use link to see paper's listing under its alternate paper code
	J.M. Coello de Portugal, F.S. Carlier, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, T. Persson, P.K. Skowroński, R. Tomás CERN, Geneva, Switzerland
	For the high luminosity upgrade of the LHC optics correction in the interaction regions is expected to be challenged by the very low β^* and the sizable expected quadrupolar errors in the triplet. This paper addresses the performance and limitations of the segment-by-segment technique to correct quadrupolar and skew quadrupolar errors in the HL-LHC IR via computer simulations. Required improvements to this technique and possible combinations with other correction approaches are also presented including experimental tests in the current LHC IR.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR040
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THPMR044	Short Term Dynamic Aperture with AC Dipoles	3496
	S. Mönig, J.M. Coello de Portugal, A. Langner, E.H. Maclean, T. Persson, R. Tomás CERN, Geneva, Switzerland
	The dynamic aperture of an accelerator is determined by its non-linear components and errors. Control of the dynamic aperture is important for a good understanding and operation of the accelerator. The AC dipole, installed in the LHC for the diagnostic of linear and non-linear optics, could serve as a tool for the determination of the dynamic aperture. However, since the AC dipole itself modifies the non-linear dynamics, the dynamic aperture with and without AC dipole are expected to differ. This paper will report the results of studies of the effect of the AC dipole on the dynamic aperture.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR044
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Experience with DOROS BPMs for Coupling Measurement and Correction

303

T. Persson, J.M. Coello de Portugal, A. Garcia-Tabares, M. Gąsior, A. Langner, T. Lefèvre, E.H. Maclean, L. Malina, J. Olexa, P.K. Skowroński, R. Tomás
CERN, Geneva, Switzerland
J. Olexa
STU, Bratislava, Slovak Republic

The Diode ORbit and OScillation System (DOROS) system is designed to provide accurate measurements of the beam position in the LHC. The oscillation part of the system, which is able to provide turn-by-turn data, is used to measure the transverse coupling. Since the system provides high resolution measurements for many turns only small excitations are needed to accurately measure the transverse coupling. In this article we present the performance the system to measure coupling and compare it to the BPMs not equipped with this system.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR029

Export •

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

THPMB041

Optics-measurement-based BPM Calibration

3328

SUPSS047

use link to see paper's listing under its alternate paper code

A. Garcia-Tabares, F.S. Carlier, J.M. Coello de Portugal, A. Langner, E.H. Maclean, L. Malina, T. Persson, P.K. Skowroński, M. Solfaroli Camillocci, R. Tomás
CERN, Geneva, Switzerland

The LHC beta functions (β) can be measured using the phase or the amplitude of betatron oscillations obtained with beam position monitors (BPMs). Using the amplitude information results in a β measurement affected by BPM calibration. This work aims at calibrating BPMs using optics measurements. For this, βs from amplitude and phase and normalized dispersion obtained from many different measurements in 2015 with different optics and corrections are analyzed. Simulations are also performed to support the analyses.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB041

Export •

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

THPMB044

Limitations on Optics Measurements in the LHC

3339

P.K. Skowroński, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, M. McAteer, T. Persson, R. Tomás
CERN, Geneva, Switzerland
A. Langner
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
L. Malina
University of Oslo, Oslo, Norway

In preparation of the optics commissioning at an energy of 6.5 TeV, many improvements have been done to cope with the expected reduced signal to noise ratio due to lowered bunch intensities imposed by machine protection considerations. This included, among others, an increase of the flat top duration of the AC dipole excitations, which allowed to use more turn-by-turn data for the analysis. The longer data acquisition revealed slow drifts of the optics, which limited the increased measurement precision. Furthermore, we will present how orbit drifts influenced dispersion measurements and, as a consequence, posed another limitation for the optics correction. In this paper we will discuss the implications of these observations for the measurement and correction of the optics.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB044

Export •

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

THPMR037

Observations of Resonance Driving Terms in the LHC during Runs I and II

3468

F.S. Carlier, J.M. Coello de Portugal, E.H. Maclean, T. Persson, R. Tomás
CERN, Geneva, Switzerland

Future operations of the LHC will require a good understanding of the nonlinear beam dynamics. In 2012, turn-by-turn measurements of large diagonal betatron excitations in LHC Beam 2 were taken at injection energy. Spectral analysis of these measurements shows an anomalous octupolar spectral line at frequency -Qx-2Qy in the horizontal motion. The presence of this spectral line, as well as other lines, was confirmed by measurements taken for LHC Beam 1 and Beam 2 during the commissioning in 2015. We take a close look at the various spectral lines appearing in the LHC transverse motion in order to improve the LHC nonlinear model.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR037

Export •

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

THPMR038

Non-Linear Errors in the Experimental Insertions of the LHC

3472

E.H. Maclean, F.S. Carlier, M. Giovannozzi, A. Langner, S. Mönig, T. Persson, P.K. Skowroński, R. Tomás
CERN, Geneva, Switzerland

Correction of nonlinear magnetic errors in low-β insertions can be of critical significance for the operation of a collider. This is expected to be of particular relevance to LHC Run II and the HL-LHC upgrade, as well as to future colliders such as the FCC. Current correction strategies for these accelerators have assumed it will be possible to calculate optimized local corrections through the insertions using a magnetic model of the errors. To test this assumption the nonlinear errors in the LHC experimental insertions have been examined via feed-down and amplitude detuning. It will be shown that while in some cases the magnetic measurements provide a sufficient description of the errors, in others large discrepancies exist which will require beam-based correction techniques.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR038

Export •

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

THPMR039

Commissioning of Non-linear Optics in the LHC at Injection Energy

3476

E.H. Maclean, F.S. Carlier, J.M. Coello de Portugal, A. Garcia-Tabares, A. Langner, L. Malina, T. Persson, P.K. Skowroński, R. Tomás
CERN, Geneva, Switzerland

Commissioning of the nonlinear optics at injection in the LHC was carried out for the first time in 2015 via beam-based methods. Building upon studies performed during Run I, corrections to the nonlinear chromaticity and detuning with amplitude were obtained. These corrections were observed to reduce beam-loss during measurement of linear optics.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR039

Export •

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

THPMR040

Local Optics Corrections in the HL-LHC IR

3480

SUPSS046

use link to see paper's listing under its alternate paper code

J.M. Coello de Portugal, F.S. Carlier, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, T. Persson, P.K. Skowroński, R. Tomás
CERN, Geneva, Switzerland

For the high luminosity upgrade of the LHC optics correction in the interaction regions is expected to be challenged by the very low β^* and the sizable expected quadrupolar errors in the triplet. This paper addresses the performance and limitations of the segment-by-segment technique to correct quadrupolar and skew quadrupolar errors in the HL-LHC IR via computer simulations. Required improvements to this technique and possible combinations with other correction approaches are also presented including experimental tests in the current LHC IR.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR040

Export •

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

THPMR044

Short Term Dynamic Aperture with AC Dipoles

3496

S. Mönig, J.M. Coello de Portugal, A. Langner, E.H. Maclean, T. Persson, R. Tomás
CERN, Geneva, Switzerland

The dynamic aperture of an accelerator is determined by its non-linear components and errors. Control of the dynamic aperture is important for a good understanding and operation of the accelerator. The AC dipole, installed in the LHC for the diagnostic of linear and non-linear optics, could serve as a tool for the determination of the dynamic aperture. However, since the AC dipole itself modifies the non-linear dynamics, the dynamic aperture with and without AC dipole are expected to differ. This paper will report the results of studies of the effect of the AC dipole on the dynamic aperture.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR044

Export •

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