Time-Correlated Single-Photon Counting for versatile longitudinal diagnostics at the MAX IV Laboratory storage rings

TL;DR

This paper demonstrates the implementation of Time-Correlated Single-Photon Counting (TCSPC) at MAX IV to non-invasively measure electron bunch profiles, enhancing diagnostics for synchrotron light source operation.

Contribution

It introduces a TCSPC-based diagnostic tool integrated into MAX IV's control system for real-time longitudinal beam profile measurements.

Findings

Successful measurement of bunch length and profiles.

Enhanced diagnostic capabilities in presence of Landau cavities.

Real-time monitoring integrated into control system.

Abstract

Precise diagnostic on the electron beam parameters is a very valuable tool and essential in the operation of synchrotron light sources. One possible option is to employ the emitted synchrotron radiation for non-destructive measurements. A tool, which has been used in many ring based synchrotron light sources is Time-Correlated Single-Photon Counting (TCSPC). It allows to measure the arrival time distribution of the emitted photons and by that reveals the filling pattern, i.e., the charge distribution onto the electron bunches stored in the storage ring. At MAX IV, two TCSPC setups were installed and the analysis was developed further to also allow for the measurement of the longitudinal profiles of the individual bunches. The analysis is available as a Tango device in the accelerator control system and continuously provides, for example, the bunch length of each bunch as well as the bunch profiles and phases. This improved the diagnostic capabilities significantly, for example, in the presence of Landau cavities, which are becoming increasingly more common in new fourth-generation synchrotron light sources.