IPAC2018 - List of Authors (Lefevre, T.)

Paper	Title	Page
WEPAF074	Non-invasive Beam Diagnostics with Cherenkov Diffraction Radiation	2005
	T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni CERN, Geneva, Switzerland L.Y. Bartnik, M.G. Billing, Y.B.P. Bordlemay Padilla, J.V. Conway, M.J. Forster, J.P. Shanks, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M. Bergamaschi, P. Karataev Royal Holloway, University of London, Surrey, United Kingdom V.V. Bleko, A.S. Konkov, J.S. Markova, A. Potylitsyn TPU, Tomsk, Russia L. Bobb DLS, Oxfordshire, United Kingdom K. Lekomtsev JAI, Egham, Surrey, United Kingdom
	Based on recent measurements of incoherent Cherenkov Diffraction Radiation (ChDR) performed on the Cornell Electron Storage Ring, we present here a concept for the centering of charged particle beams when passing close to dielectric material. This would find applications as beam instrumentation in dielectric capillary tubes, typically used in novel accelerating technologies, as well as in collimators using bent crystals for high-energy, high-intensity hadron beams, such as the Large Hadron Collid-er or Future Circular Collider. As a charged particle beam travels at a distance of a few mm or less from the surface of a dielectric material, incoherent ChDR is produced inside the dielectric. The photons are emitted at a large and well-defined angle that allows their detection with a limited contribution of background light. A set of ChDR detectors distributed around a dielectric would enable both the beam position and tilt angle to be measured with a good resolution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF074
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WEPAF080	Beam Size Measurements Based on Movable Quadrupolar Pick-ups	2028
	A. Sounas, M. Gąsior, T. Lefèvre, A. Mereghetti, J. Olexa, S. Redaelli, G. Valentino CERN, Geneva, Switzerland
	Measurements with quadrupolar pick-ups (PU) have attracted particular interest as non-intercepting diagnostics for determining the transverse beam size. They are based on processing the signals of an electromagnetic PU for the extraction of the second-order moment, which contains information about the beam size. Despite the simplicity of the concept, quadrupololar measurements have always been highly challenging in reality. This comes from the fact that the quadrupolar moment constitutes only a very small part of the total PU signal dominated by the intensity and the position signals. Therefore, the beam size information can easily be lost due to small imperfections in the signal processing chain, such as asymmetries in the electronics and cables. In this paper, we present a new method for quadrupolar measurements using movable PUs. Through position and aperture scans, our technique minimizes the parasitic beam position signal and takes into account imperfections of the PU, cables and electronics, thus enabling an efficient auto-calibration of the measurement system. Preliminary studies, using collimators with embedded electrostatic PUs in the LHC at CERN, have shown very promising results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF080
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WEPAL073	Enhanced Bunch Monitoring by Interferometric Electro-Optic Methods	2353
	S.M. Gibson, A. Arteche, A. Bosco Royal Holloway, University of London, Surrey, United Kingdom S.E. Bashforth, A. Bosco, S.M. Gibson JAI, Egham, Surrey, United Kingdom M. Krupa, T. Lefèvre CERN, Geneva, Switzerland
	Funding: We acknowledge funding by UK STFC grant ST/N001583/1, JAI at Royal Holloway University of London and CERN A prototype Electro-Optic Beam Position Monitor has been installed for tests* in the CERN SPS to develop the concept for high-bandwidth (6-12GHz) monitoring of crabbed-bunch rotation and intra-bunch instabilities at the High Luminosity LHC*. The technique relies on the ultrafast response of birefringent MgO:LiNO3 crystals to optically measure the intra-bunch transverse displacement of a passing relativistic bunch. This paper reports on recent developments, including a new interferometric electro-optic pick-up that was installed in the CERN SPS in September 2017; in first beam tests with nominal bunch charge, a corresponding interferometric signal has been observed. The interferometric arrangement has the advantages of being sensitive to the strongest polarisation coefficient of the crystal, and the phase offset of the interferometer is controllable by frequency scanning of the laser, which enables rapid optimisation of the working point. Novel concepts and bench tests for enhancements to the pick-up design are reviewed, together with prospects for sensitivity during the first crab-cavity beam tests at the CERN SPS in 2018. A. Arteche et al "First beam tests at the CERN SPS of an electro-optic beam position monitor for the HL-LHC" TUPCF23, IBIC 2017. ** HL-LHC TDR v0.1 doi.org/10.23731/CYRM-2017-004
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL073
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THPMF014	First Experiments at the CLEAR User Facility	4066
	R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, R. Garcia Alia, T. Lefèvre, G. McMonagle, P.K. Skowroński, M. Tali, F. Tecker CERN, Geneva, Switzerland E. Adli, C.A. Lindstrøm, K.N. Sjobak University of Oslo, Oslo, Norway R.M. Jones, A. Lagzda UMAN, Manchester, United Kingdom
	The new "CERN Linear Electron Accelerator for Research" (CLEAR) facility at CERN started its operation in fall 2017. CLEAR results from the conversion of the CALIFES beam line of the former CLIC Test Facility (CTF3) into a new testbed for general accelerator R&D and component studies for existing and possible future accelerator applications. CLEAR can provide a stable and reliable electron beam from 60 to 220 MeV in single or multi bunch configuration at 1.5 GHz. The experimental program includes studies for high gradient acceleration methods, e.g. for CLIC X-band and plasma technology, prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade, and irradiation test capabilities for characterization of electronic components and for medical applications. An overview of the facility capabilities and a summary of the latest results will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF014
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THPMK103	Initial Testing of Techniques for Large Scale Rf Conditioning for the Compact Linear Collider	4548
SUSPF019	use link to see paper's listing under its alternate paper code
	T.G. Lucas, M.J. Boland, P.J. Giansiracusa, R.P. Rassool, M. Volpi The University of Melbourne, Melbourne, Victoria, Australia N. Catalán Lasheras, A. Grudiev, T. Lefèvre, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano CERN, Geneva, Switzerland J. Paszkiewicz University of Oxford, Oxford, United Kingdom C. Serpico Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy A. Vnuchenko IFIC, Valencia, Spain R. Zennaro PSI, Villigen PSI, Switzerland
	Nominal operating conditions for the Compact Linear Collider (CLIC) 380 GeV requires 72 MV/m loaded accelerating gradients for a 180 ns flat-top pulse. Achieving this requires extensive RF conditioning which past tests have demonstrated can take several months per structure, when conditioned at the nominal repetition rate of 50 Hz. At CERN there are three individual X-band test stands currently operational, testing up to 6 structures concurrently. For CLIC's 380 GeV design, 28,000 accelerating structures will make up the main linac. For a large scale conditioning programme, it is important to understand the RF conditioning process and to optimise the time taken for conditioning. In this paper, we review recent X-band testing results from CERN's test stands. With these results we investigate how to optimise the conditioning process and demonstrate the feasibility of pre-conditioning the structures at a higher repetition rate before installation into the main linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK103
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Paper

Title

Page

Non-invasive Beam Diagnostics with Cherenkov Diffraction Radiation

2005

T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni
CERN, Geneva, Switzerland
L.Y. Bartnik, M.G. Billing, Y.B.P. Bordlemay Padilla, J.V. Conway, M.J. Forster, J.P. Shanks, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
M. Bergamaschi, P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
V.V. Bleko, A.S. Konkov, J.S. Markova, A. Potylitsyn
TPU, Tomsk, Russia
L. Bobb
DLS, Oxfordshire, United Kingdom
K. Lekomtsev
JAI, Egham, Surrey, United Kingdom

Based on recent measurements of incoherent Cherenkov Diffraction Radiation (ChDR) performed on the Cornell Electron Storage Ring, we present here a concept for the centering of charged particle beams when passing close to dielectric material. This would find applications as beam instrumentation in dielectric capillary tubes, typically used in novel accelerating technologies, as well as in collimators using bent crystals for high-energy, high-intensity hadron beams, such as the Large Hadron Collid-er or Future Circular Collider. As a charged particle beam travels at a distance of a few mm or less from the surface of a dielectric material, incoherent ChDR is produced inside the dielectric. The photons are emitted at a large and well-defined angle that allows their detection with a limited contribution of background light. A set of ChDR detectors distributed around a dielectric would enable both the beam position and tilt angle to be measured with a good resolution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF074

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

WEPAF080

Beam Size Measurements Based on Movable Quadrupolar Pick-ups

2028

A. Sounas, M. Gąsior, T. Lefèvre, A. Mereghetti, J. Olexa, S. Redaelli, G. Valentino
CERN, Geneva, Switzerland

Measurements with quadrupolar pick-ups (PU) have attracted particular interest as non-intercepting diagnostics for determining the transverse beam size. They are based on processing the signals of an electromagnetic PU for the extraction of the second-order moment, which contains information about the beam size. Despite the simplicity of the concept, quadrupololar measurements have always been highly challenging in reality. This comes from the fact that the quadrupolar moment constitutes only a very small part of the total PU signal dominated by the intensity and the position signals. Therefore, the beam size information can easily be lost due to small imperfections in the signal processing chain, such as asymmetries in the electronics and cables. In this paper, we present a new method for quadrupolar measurements using movable PUs. Through position and aperture scans, our technique minimizes the parasitic beam position signal and takes into account imperfections of the PU, cables and electronics, thus enabling an efficient auto-calibration of the measurement system. Preliminary studies, using collimators with embedded electrostatic PUs in the LHC at CERN, have shown very promising results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF080

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WEPAL073

Enhanced Bunch Monitoring by Interferometric Electro-Optic Methods

2353

S.M. Gibson, A. Arteche, A. Bosco
Royal Holloway, University of London, Surrey, United Kingdom
S.E. Bashforth, A. Bosco, S.M. Gibson
JAI, Egham, Surrey, United Kingdom
M. Krupa, T. Lefèvre
CERN, Geneva, Switzerland

Funding: We acknowledge funding by UK STFC grant ST/N001583/1, JAI at Royal Holloway University of London and CERN
A prototype Electro-Optic Beam Position Monitor has been installed for tests* in the CERN SPS to develop the concept for high-bandwidth (6-12GHz) monitoring of crabbed-bunch rotation and intra-bunch instabilities at the High Luminosity LHC**. The technique relies on the ultrafast response of birefringent MgO:LiNO3 crystals to optically measure the intra-bunch transverse displacement of a passing relativistic bunch. This paper reports on recent developments, including a new interferometric electro-optic pick-up that was installed in the CERN SPS in September 2017; in first beam tests with nominal bunch charge, a corresponding interferometric signal has been observed. The interferometric arrangement has the advantages of being sensitive to the strongest polarisation coefficient of the crystal, and the phase offset of the interferometer is controllable by frequency scanning of the laser, which enables rapid optimisation of the working point. Novel concepts and bench tests for enhancements to the pick-up design are reviewed, together with prospects for sensitivity during the first crab-cavity beam tests at the CERN SPS in 2018.
* A. Arteche et al "First beam tests at the CERN SPS of an electro-optic beam position monitor for the HL-LHC" TUPCF23, IBIC 2017.
** HL-LHC TDR v0.1 doi.org/10.23731/CYRM-2017-004

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL073

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THPMF014

First Experiments at the CLEAR User Facility

4066

R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, R. Garcia Alia, T. Lefèvre, G. McMonagle, P.K. Skowroński, M. Tali, F. Tecker
CERN, Geneva, Switzerland
E. Adli, C.A. Lindstrøm, K.N. Sjobak
University of Oslo, Oslo, Norway
R.M. Jones, A. Lagzda
UMAN, Manchester, United Kingdom

The new "CERN Linear Electron Accelerator for Research" (CLEAR) facility at CERN started its operation in fall 2017. CLEAR results from the conversion of the CALIFES beam line of the former CLIC Test Facility (CTF3) into a new testbed for general accelerator R&D and component studies for existing and possible future accelerator applications. CLEAR can provide a stable and reliable electron beam from 60 to 220 MeV in single or multi bunch configuration at 1.5 GHz. The experimental program includes studies for high gradient acceleration methods, e.g. for CLIC X-band and plasma technology, prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade, and irradiation test capabilities for characterization of electronic components and for medical applications. An overview of the facility capabilities and a summary of the latest results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF014

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THPMK103

Initial Testing of Techniques for Large Scale Rf Conditioning for the Compact Linear Collider

4548

SUSPF019

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

T.G. Lucas, M.J. Boland, P.J. Giansiracusa, R.P. Rassool, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia
N. Catalán Lasheras, A. Grudiev, T. Lefèvre, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano
CERN, Geneva, Switzerland
J. Paszkiewicz
University of Oxford, Oxford, United Kingdom
C. Serpico
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Vnuchenko
IFIC, Valencia, Spain
R. Zennaro
PSI, Villigen PSI, Switzerland

Nominal operating conditions for the Compact Linear Collider (CLIC) 380 GeV requires 72 MV/m loaded accelerating gradients for a 180 ns flat-top pulse. Achieving this requires extensive RF conditioning which past tests have demonstrated can take several months per structure, when conditioned at the nominal repetition rate of 50 Hz. At CERN there are three individual X-band test stands currently operational, testing up to 6 structures concurrently. For CLIC's 380 GeV design, 28,000 accelerating structures will make up the main linac. For a large scale conditioning programme, it is important to understand the RF conditioning process and to optimise the time taken for conditioning. In this paper, we review recent X-band testing results from CERN's test stands. With these results we investigate how to optimise the conditioning process and demonstrate the feasibility of pre-conditioning the structures at a higher repetition rate before installation into the main linac.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK103

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