Longitudinal Schottky signal spectrum at heavy-ion storage ring: Simulation and analysis

The heavy-ion accelerator cooler storage ring provides a unique experimental platform for precision measurements with highly charged ions and interdisciplinary research. As one of the most powerful beam diagnostic devices, the Schottky resonator system can be used to nondestructively monitor beam qualities and as a critical instrument for various in-ring experiments, e.g., analyzing of beam cooling dynamics and measuring the fundamental properties of exotic nuclei. In this article, the properties of the longitudinal Schottky signal spectrum of the coasting ion beam are studied via theoretical derivation and simulation analysis. On this basis, the structure and characteristics of the longitudinal Schottky signal spectrum of bunched ion beams are systematically simulated and analyzed. Furthermore, a new method is proposed and simulated for accurately reconstructing the momentum distribution of bunched ion beams from the longitudinal Schottky signal spectrum. Finally, the simulation results are verified with the experimentally measured longitudinal Schottky signal spectrum at the storage ring CSRe. These studies establish a solid foundation for analyzing cooling dynamics and beam property diagnostics during the laser cooling of relativistic bunched heavy-ion beams. Moreover, they strongly support other experiments based on the longitudinal Schottky signal spectrum, such as stochastic cooling, electron cooling, and nuclear mass and lifetime measurements.