CERN Accelerating science

Published Articles
Report number	CERN-ACC-2018-098
Title	Commissioning of the Operational Laser Emittance Monitors for LINAC4 at CERN
Author(s)	Hofmann, Thomas (Royal Holloway, U. of London) ; Boorman, Gary (Royal Holloway, U. of London) ; Bosco, Alessio (Royal Holloway, U. of London) ; Gibson, Stephen (Royal Holloway, U. of London) ; Roncarolo, Federico (CERN)
Publication	2018
Number of pages	4
In:	9th International Particle Accelerator Conference, Vancouver, Canada, 29 Apr - 4 May 2018, pp.WEPAL074
DOI	10.18429/JACoW-IPAC2018-WEPAL074
Subject category	Accelerators and Storage Rings
Accelerator/Facility, Experiment	CERN LINAC4
Abstract	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.
Copyright/License	CC-BY-3.0

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