Resonant island trapping in a hybrid multibend achromat synchrotron light source

We report the first direct experimental observations of resonance island formation in a hybrid multibend achromat (HMBA) storage ring lattice. Using a low-emittance electron beam, we achieved high-precision measurements that resolve the onset, evolution, and transient dynamics of particle capture near resonance islands. These measurements are compared with simulation predictions, enabling a direct validation of HMBA lattice models. The experimental results also provide new insight into the capture and trapping mechanisms governing the island population, as well as beam lifetime in resonance islands. Together, these findings establish a detailed experimental basis for understanding nonlinear dynamics in next-generation HMBA-based synchrotron light sources.