Design and deployment of an in-vacuum Electro-Optic BPM at the CERN SPS

Accurate monitoring and control of charged particle beams at the HL-LHC demands the development of new beam diagnostics tools. This poster provides an overview of the electro-optic beam position monitor (EO-BPM), currently taking measurements at CERN's SPS. This device uses the Pockels effect to monitor the transverse position and instabilities in the particle beam. Comprising of a laser source, electro-optic crystal, optical system, and a fast photodetector, the EO-BPM operates by generating a modulated optical signal directly linked to the propagating electric field of the beam. The EO-BPM is designed as a self containing button with fibre-coupled laser connected to the crystal inside and a fibre coupled Mach-Zehnder interferometer yielding sum and difference signals on the outside. A segment of the SPS beam pipe is fitted with a mount to connect the button, allowing the electric field induced by the particle beam to be captured and transferred to the electro-optic crystal. The goal is to gain insight into the transverse position along the bunch and the identification of intra-bunch instabilities, contributing to precision in beam monitoring and control.