Göttingen 2025 – wissenschaftliches Programm

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 6: Accelerators for Medical Applications (joint session ST/AKBP)

AKBP 6.7: Vortrag

Mittwoch, 2. April 2025, 15:30–15:45, ZHG009

Acoustic tracing of dose deposition of laser accelerated ion-bunches by modulation of the depth-dose curve — •Jeannette Cadeggianini, Alexander Prasselsperger, Anna-Katharina Schmidt, and Jörg Schreiber — Ludwig-Maximilian-Universität, München, Germany

A high-repetition-rate online dose reconstruction method is crucial for accelerated particle applications. Ionoacoustic measurements determine monoenergetic ion energies by recording acoustic signals generated by localized thermal expansion in the Bragg region. These waveforms encode the ion beam's energy and spatial distribution.

However, this method depends on pronounced spatial energy density gradients, which are absent in laser-accelerated ion beams, which exhibit broad, exponential energy spectra. To address this, we introduce TIMBRE (Tracing Ionoacoustic Modulations of Broad Energy Distributions), which uses modulator foils to create steeper energy deposition gradients. These foils serve two functions: due to the materials the stopping power in the foils is higher than in the interspaces, generating an acoustic wave at each interface because of the steep pressure gradient. Simultaneously, each foil reduces the amplitude of the signals from shallower foils, compressing the dynamic range.

By unfolding the measured acoustic traces with the corresponding analytic model, TIMBRE reconstructs depth dose distributions of laser-accelerated ion bunches. It offers a real-time diagnostic, supporting modern accelerators operating at Hz-level repetition rates and beyond.

Keywords: Ionoacoustics; Bragg peak; online detector; accelerated ions