Solid-state acoustic detection of laser-accelerated proton beams for transient flow intensity monitoring

Laser-accelerated proton beams deliver ultrashort, high transient flow energy deposition that remains challenging to diagnose in real time. Here, we report a proof-of-principle observation of acoustic waves generated by laser-accelerated protons in solid media and investigate solid-state thermoacoustic conversion as a potential approach for sensing ultrahigh-intensity proton beams. Localized proton energy deposition induces transient heating and stress formation in an aluminum target, producing measurable MHz acoustic signals after the electromagnetic pulse interference is separated from the acoustic response. By combining experiments with multiphysics simulations, we examine the proton-driven origin of the signals, quantify their propagation-distance-dependent attenuation, and observe an approximately linear correlation between the reconstructed acoustic pressure and the estimated proton flow intensity. Measurements with a tungsten target further support the robustness and multi-material applicability of the solid-state acoustic response. These results extend proton-induced acoustics from liquid-based range-verification studies toward solid media, where thermoacoustic signals may provide a complementary observable for transient high-current proton beams in vacuum-compatible and electromagnetically harsh environments, with possible extensions to acoustic signaling through solid structures under extreme conditions.