Beam monitoring and dosimetry for in vivo studies with laser-driven protons at Draco PW

Petawatt laser-plasma based proton sources, capable of providing multi-10 MeV proton pulses at ultra-high dose rates of 10^9 Gy/s, are unique sources for radiobiological studies of ~mm size 3D in vivo samples in the recently strongly investigated FLASH regime.
At Draco PW (HZDR), a compact and tunable pulsed power beamline is utilized for efficient beam transport and spectral filtering for dose deposition in a sample. The setup was successfully used for in vivo radiobiological studies with up to 20 Gy single shot doses as well as for accumulative multi-shot low dose (~500 mGy) schemes for %-level accuracy of dose delivery.
Regarding beam monitoring and dosimetry, the inherent fluctuations of the laser-driven source, the ultra-high dose rate and the experimental environment (pulsed power, EMP) pose challenges for established dosimetry methods.
In this presentation, we present a non-invasive scintillator-based time-of-flight spectrometer as a unique tool for single-shot online beam optimization and monitoring of laser-driven proton pulses in application experiments. Calibration of the device against established dosimeters (here radiochromic film) in combination with Monto Carlo simulations additionally allows dosimetric use, overcoming saturation issues with dose rate or linear energy transfer present in other devices.
To illustrate the suitability of the time-of-flight spectrometer as a beam monitor and absolute dosimeter for laser-based protons, the time-of-flight data of two radiobiological in vivo irradiation campaigns performed at the implemented beamline at the DRACO PW facility are presented.