IPAC2017 - List of Authors (Papotti, G.)

Paper	Title	Page
MOPAB109	Operational Experience with Luminosity Scans for Beam Size Estimation in 2016 LHC Proton Physics Operation	374
	M. Hostettler LHEP, Bern, Switzerland K. Fuchsberger, G. Papotti CERN, Geneva, Switzerland
	Luminosity scans were regularly performed at the CERN Large Hadron Collider (LHC) as of 2015 as a complementary method for measuring the beam size. The CMS experiment provides bunch-by-bunch luminosities at sufficient rates to allow evaluation of bunch-by-bunch beam sizes, and the scans are performed in the horizontal and vertical plane separately. Closed orbit differences between bunches can also be derived by this analysis. During 2016 LHC operation, these scans were also done in an automated manner on a regular basis, and the analysis was improved to significantly reduce the systematic uncertainty, especially in the crossing plane. This contribution first highlights the recent improvements to the analysis and elaborates on their impact. The measured beam sizes during 2016 proton physics operation are then shown and compared to measurements from synchrotron light telescopes and estimates based on the absolute luminosities of the LHC experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB109
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MOPAB110	Comparison of Transverse Emittance Measurements in the LHC	377
	M. Hostettler, R. Alemany-Fernández, F. Alessio, M. Ferro-Luzzi, K. Fuchsberger, G. Iadarola, R. Matev, S. Papadopoulou, Y. Papaphilippou, G. Papotti, G. Trad CERN, Geneva, Switzerland F. Antoniou The University of Liverpool, Liverpool, United Kingdom G.R. Coombs University of Glasgow, Glasgow, United Kingdom T.B. Hadavizadeh Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Transverse emittance measurement in a collider is of crucial importance for understanding beam dynamics observations and evaluating the machine performance. Devices measuring the beam emittance face the challenge of dealing with considerable systematic errors that can compromise the quality of the measurement. Having different instruments or techniques that provide beam size estimations in order to compare the outcome and give an unbiased value of the emittance is very important in a collider. The comparison of the different results is as well very useful to identify possible problems in a given equipment which could remain unnoticed if such device is the only source of emittance reconstruction. In the LHC several of these instruments and techniques are available; wire scanners, synchrotron light monitors, emittance reconstruction from transverse convolved beam sizes extracted from luminosity scans at the LHC collision points and from beam-gas imaging in the vertex detector of the LHCb experiment. Those systems are briefly presented in this paper together with the comparison of the emittances reconstructed by each of them during physics production over the 2016 LHC run.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB110
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TUPVA005	Impact of the Crossing Angle on Luminosity Asymmetries at the LHC in 2016 Proton Physics Operation	2035
SUSPSIK001	use link to see paper's listing under its alternate paper code
	M. Hostettler LHEP, Bern, Switzerland F. Antoniou, I. Efthymiopoulos, K. Fuchsberger, G. Iadarola, N. Karastathis, M. Lamont, Y. Papaphilippou, G. Papotti, J. Wenninger CERN, Geneva, Switzerland
	During 2016 proton physics operation at the CERN Large Hadron Collider (LHC), an asymmetry of up to 10% was observed between the luminosities measured by the ATLAS and CMS experiments. As the same bunch pairs collide in both experiments, a difference in luminosities must be of either geometric or instrumental origin. This paper quantifies the impact of the crossing angle on this asymmetry. As the beams cross in different planes in the two experiments, non-round beams are expected to yield an asymmetry due to the crossing angle. Results from crossing angle measurements at both experiments are also shown and the impact on the luminosities is evaluated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA005
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WEOBA2	Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core	2482
	M. Fitterer, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA R. Bruce, G. Papotti, S. Redaelli, D. Valuch, C. Xu CERN, Geneva, Switzerland G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy. Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.
	Slides WEOBA2 [2.074 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOBA2
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Paper

Title

Page

Operational Experience with Luminosity Scans for Beam Size Estimation in 2016 LHC Proton Physics Operation

374

M. Hostettler
LHEP, Bern, Switzerland
K. Fuchsberger, G. Papotti
CERN, Geneva, Switzerland

Luminosity scans were regularly performed at the CERN Large Hadron Collider (LHC) as of 2015 as a complementary method for measuring the beam size. The CMS experiment provides bunch-by-bunch luminosities at sufficient rates to allow evaluation of bunch-by-bunch beam sizes, and the scans are performed in the horizontal and vertical plane separately. Closed orbit differences between bunches can also be derived by this analysis. During 2016 LHC operation, these scans were also done in an automated manner on a regular basis, and the analysis was improved to significantly reduce the systematic uncertainty, especially in the crossing plane. This contribution first highlights the recent improvements to the analysis and elaborates on their impact. The measured beam sizes during 2016 proton physics operation are then shown and compared to measurements from synchrotron light telescopes and estimates based on the absolute luminosities of the LHC experiments.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB109

Export •

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

MOPAB110

Comparison of Transverse Emittance Measurements in the LHC

377

M. Hostettler, R. Alemany-Fernández, F. Alessio, M. Ferro-Luzzi, K. Fuchsberger, G. Iadarola, R. Matev, S. Papadopoulou, Y. Papaphilippou, G. Papotti, G. Trad
CERN, Geneva, Switzerland
F. Antoniou
The University of Liverpool, Liverpool, United Kingdom
G.R. Coombs
University of Glasgow, Glasgow, United Kingdom
T.B. Hadavizadeh
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Transverse emittance measurement in a collider is of crucial importance for understanding beam dynamics observations and evaluating the machine performance. Devices measuring the beam emittance face the challenge of dealing with considerable systematic errors that can compromise the quality of the measurement. Having different instruments or techniques that provide beam size estimations in order to compare the outcome and give an unbiased value of the emittance is very important in a collider. The comparison of the different results is as well very useful to identify possible problems in a given equipment which could remain unnoticed if such device is the only source of emittance reconstruction. In the LHC several of these instruments and techniques are available; wire scanners, synchrotron light monitors, emittance reconstruction from transverse convolved beam sizes extracted from luminosity scans at the LHC collision points and from beam-gas imaging in the vertex detector of the LHCb experiment. Those systems are briefly presented in this paper together with the comparison of the emittances reconstructed by each of them during physics production over the 2016 LHC run.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB110

Export •

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

TUPVA005

Impact of the Crossing Angle on Luminosity Asymmetries at the LHC in 2016 Proton Physics Operation

2035

SUSPSIK001

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

M. Hostettler
LHEP, Bern, Switzerland
F. Antoniou, I. Efthymiopoulos, K. Fuchsberger, G. Iadarola, N. Karastathis, M. Lamont, Y. Papaphilippou, G. Papotti, J. Wenninger
CERN, Geneva, Switzerland

During 2016 proton physics operation at the CERN Large Hadron Collider (LHC), an asymmetry of up to 10% was observed between the luminosities measured by the ATLAS and CMS experiments. As the same bunch pairs collide in both experiments, a difference in luminosities must be of either geometric or instrumental origin. This paper quantifies the impact of the crossing angle on this asymmetry. As the beams cross in different planes in the two experiments, non-round beams are expected to yield an asymmetry due to the crossing angle. Results from crossing angle measurements at both experiments are also shown and the impact on the luminosities is evaluated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA005

Export •

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

WEOBA2

Hollow Electron Beam Collimation for HL-LHC - Effects on the Beam Core

2482

M. Fitterer, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA
R. Bruce, G. Papotti, S. Redaelli, D. Valuch, C. Xu
CERN, Geneva, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the US Department of Energy.
Collimation with hollow electron beams is currently one of the most promising concepts for active halo control in the High Luminosity Large Hadron Collider (HL-LHC). To ensure the successful operation of the hollow beam collimator the unwanted effects on the beam core, which might arise from the operation with a pulsed electron beam, must be minimized. This paper gives a summary of the effect of hollow electron lenses on the beam core in terms of sources, provides estimates for HL-LHC and discusses the possible mitigation methods.

Slides WEOBA2 [2.074 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOBA2

Export •

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