Enhanced Bunch Monitoring by Interferometric Electro-Optic Methods

Stephen Gibson, Alberto Arteche, Sophie Bashforth, Alessio Bosco, Michal Krupa, Thibaut Lefevre

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A prototype Electro-Optic Beam Position Monitor has been installed for tests in the CERN SPS to develop the concept for high-bandwidth (6-12 GHz) 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 polarization 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.
Original languageEnglish
Title of host publication9th International Particle Accelerator Conference
Place of PublicationGeneva
PublisherJACoW Publishing
Number of pages4
ISBN (Electronic)978-3-95450-184-7
Publication statusPublished - Jun 2018

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