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We established an experimental platform for the investigation of the radiobiological effects of stable few-MeV laser-accelerated ions at the BELLA Center using a peak laser pulse intensity of 2x1019 W cm-2 [1]. The focal spot size of laser pulses from the BELLA PW laser system is large compared to that found in typical laser-driven ion beamlines, which resulted in reduced divergence and increased ion numbers [2]. Such beams are ideally suited for subsequent capture and transport with an active plasma lens (APL) [3]. Combined with our high shot rate capability (0.2 Hz), around 1000 shots at ultra-high instantaneous dose rates (0.6 Gy/shot resulting in 107 Gy/s), with a uniform dose distribution over a 1 cm diameter lateral area, could thus be delivered to biological cell sample cups, located in air at 1.7 m distance from the laser-target interaction. The proton beamline was complemented by online (integrating current transformer and scintillator) and offline (radiochromic films) beam diagnostics for dosimetry. This assembly was used to investigate the differential sparing of healthy tissues versus the tumor response under reduced oxygen conditions. This talk gives details on the proton beamline, dosimetry as well as preliminary cell irradiation results.
This work is supported by U.S. Department of Energy Office of Science, Offices of High Energy Physics and Fusion Energy Sciences, Contract No. DE-AC02-05CH11231 and LBNL Laboratory Directed Research and Development Grant, PI A. M. Snijders
[1] K. Nakamura, et al., Diagnostics, Control and Performance Parameters for the BELLA High Repetition Rate Petawatt Class Laser, IEEE J. Quantum Electron., 53, (2017), 1200121 [2] S. Steinke, et al., Acceleration of high charge ion beams with achromatic divergence by petawatt laser pulses, Phys. Rev. Accel. Beams, 23, (2020), 021302
[3] J. Van Tilborg, et al., Active Plasma Lensing for Relativistic Laser-Plasma-Accelerated Electron Beams, Phys. Rev. Lett., 115, (2015), 184802
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