Speaker
Description
Precise characterization of the electron bunch length in storage rings is essential for understanding longitudinal beam dynamics and instabilities. While Time-Correlated Single Photon Counting (TCSPC) is widely used for this purpose, the conventional accumulated temporal profile is often artificially broadened by the longitudinal center-of-mass oscillations of the bunch relative to the RF bucket. To mitigate this limitation, we present a novel measurement and data-processing methodology implemented at the HLS-II. Instead of using dedicated timing hardware, a high-bandwidth oscilloscope is utilized to synchronously acquire both the single-photon pulses from a Photomultiplier Tube (PMT) and the pick-up signals from Beam Position Monitors (BPMs). This homodyne acquisition scheme intrinsically guarantees absolute timestamp alignment between the photon events and the turn-by-turn bunch position. Through offline digital signal processing—including precise phase extraction of the BPM signals and digital constant fraction discrimination for the PMT pulses—the instantaneous longitudinal center shift of the bunch is calculated and used to mathematically compensate the photon arrival times. Preliminary results demonstrate that this cost-effective, oscilloscope-based approach effectively decouples the intrinsic bunch length from longitudinal rigid-dipole oscillations, significantly improving the temporal resolution and providing a robust tool for transient beam dynamics diagnostics.
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| Supervisor's name | Yongbin Leng |
| Supervisor's email | lengyb@ustc.edu.cn |
| Paper submission software | MSWord |