IPAC2018 - List of Authors (Bosco, A.)

Paper	Title	Page
WEPAL072	A Novel Longitudinal Laserwire to Non-Invasively Measure 6-Dimensional Bunch Parameters at High Current Hydrogen Ion Accelerators	2349
	S.M. Gibson, A. Bosco Royal Holloway, University of London, Surrey, United Kingdom S.E. Alden, A. Bosco, S.M. Gibson JAI, Egham, Surrey, United Kingdom A.P. Letchford STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski Imperial College of Science and Technology, Department of Physics, London, United Kingdom J.K. Pozimski STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	Funding: We acknowledge funding by the STFC Grant ST/P003028/1 and the John Adams Institute at Royal Holloway, University of London. Optical methods for non-invasive beam diagnostics of high current H⁻ ion accelerators have been developed in recent years, . Such laserwires typically measure a 1D beam profile and/or 2D transverse emittance from the products of photo-detached ions as a laser beam is scanned across the H⁻ beam. For laser pulse durations (~80ns) longer than the RF period (~3ns), the detector integrates many complete bunches, enabling only transverse beam monitoring. This paper presents a new technique to capture a series of time resolved transverse emittance measurements along the bunch train. A fast (~10ps) pulsed laser photo-detaches ions within each bunch and is synchronized to sample consecutive bunches at certain longitudinal positions along each bunch. A fast detector records the spatial distribution and time-of-flight of the neutralized H⁰, thus both the transverse and longitudinal emittance are reconstructed. We present simulations of a time varying pulsed laser field interacting within an H⁻ bunch, and estimate the yield, spatial and time distributions of H⁰ arriving at the detector. We summarise the design of a recently funded longitudinal laserwire being installed in FETS at RAL, UK. NIM-A, 830, p526-531, T. Hofmann et al ** T. Hofmann et al, 'Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN' IPAC18.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL072
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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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WEPAL074	Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN	2357
	T. Hofmann, G.E. Boorman, A. Bosco, S.M. Gibson Royal Holloway, University of London, Surrey, United Kingdom F. Roncarolo CERN, Geneva, Switzerland
	A laser-based emittance monitor has been developed to non-invasively measure the transverse emittance of the LINAC4 H⁻ beam at its top energy of 160MeV. After testing several sub-systems of the instrument during linac commissioning at intermediate energies, two instruments are now permanently installed. These instruments use a pulsed laser beam delivered to the accelerator tunnel by optical fibres before final focusing onto the H⁻ beam. The photons in the laser pulse detach electrons from the H⁻ ions, which can then be deflected into an electron multiplier. In addition, the resulting neutral H⁰ atoms can be separated from the main beam by a dipole magnet before being recorded by downstream diamond strip-detectors. By scanning the laser in the horizontal and vertical plane the beam profiles are obtained from the electron signals and the emittance can be reconstructed by the H⁰ profiles at the diamond detectors. This paper describes the final system layout that consists of two independent instruments, each measuring profile and emittance of the H⁻ beam in the horizontal and vertical plane and discusses the preliminary commissioning results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL074
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Paper

Title

Page

A Novel Longitudinal Laserwire to Non-Invasively Measure 6-Dimensional Bunch Parameters at High Current Hydrogen Ion Accelerators

2349

S.M. Gibson, A. Bosco
Royal Holloway, University of London, Surrey, United Kingdom
S.E. Alden, A. Bosco, S.M. Gibson
JAI, Egham, Surrey, United Kingdom
A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
J.K. Pozimski
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Funding: We acknowledge funding by the STFC Grant ST/P003028/1 and the John Adams Institute at Royal Holloway, University of London.
Optical methods for non-invasive beam diagnostics of high current H⁻ ion accelerators have been developed in recent years*, **. Such laserwires typically measure a 1D beam profile and/or 2D transverse emittance from the products of photo-detached ions as a laser beam is scanned across the H⁻ beam. For laser pulse durations (~80ns) longer than the RF period (~3ns), the detector integrates many complete bunches, enabling only transverse beam monitoring. This paper presents a new technique to capture a series of time resolved transverse emittance measurements along the bunch train. A fast (~10ps) pulsed laser photo-detaches ions within each bunch and is synchronized to sample consecutive bunches at certain longitudinal positions along each bunch. A fast detector records the spatial distribution and time-of-flight of the neutralized H⁰, thus both the transverse and longitudinal emittance are reconstructed. We present simulations of a time varying pulsed laser field interacting within an H⁻ bunch, and estimate the yield, spatial and time distributions of H⁰ arriving at the detector. We summarise the design of a recently funded longitudinal laserwire being installed in FETS at RAL, UK.
* NIM-A, 830, p526-531, T. Hofmann et al
** T. Hofmann et al, 'Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN' IPAC18.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL072

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

WEPAL074

Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN

2357

T. Hofmann, G.E. Boorman, A. Bosco, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
F. Roncarolo
CERN, Geneva, Switzerland

A laser-based emittance monitor has been developed to non-invasively measure the transverse emittance of the LINAC4 H⁻ beam at its top energy of 160MeV. After testing several sub-systems of the instrument during linac commissioning at intermediate energies, two instruments are now permanently installed. These instruments use a pulsed laser beam delivered to the accelerator tunnel by optical fibres before final focusing onto the H⁻ beam. The photons in the laser pulse detach electrons from the H⁻ ions, which can then be deflected into an electron multiplier. In addition, the resulting neutral H⁰ atoms can be separated from the main beam by a dipole magnet before being recorded by downstream diamond strip-detectors. By scanning the laser in the horizontal and vertical plane the beam profiles are obtained from the electron signals and the emittance can be reconstructed by the H⁰ profiles at the diamond detectors. This paper describes the final system layout that consists of two independent instruments, each measuring profile and emittance of the H⁻ beam in the horizontal and vertical plane and discusses the preliminary commissioning results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL074

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