Commissioning of low particle flux for proton beams at MedAustron.

MedAustron is a synchrotron based particle therapy centre located in Wiener Neustadt, Austria. It features three irradiation rooms for particle therapy, where proton beams with energies up to 252.7 MeV and carbon ions of up to 402.8 MeV/u are available for cancer treatment. In addition to the treatment rooms, MedAustron features a unique beam line exclusively for non-clinical research (NCR). This research beam line is also commissioned for proton energies up to 800 MeV, while available carbon ion energies correspond to the ones available in the treatment rooms. All irradiation rooms offer particle rates in the order of 10^9 particles/s for protons and 10^7 particles/s for carbon ions. Such high fluxes are needed to efficiently irradiate patients in a short amount of time. However, for research purposes also lower particle fluxes are required. Therefore lower proton flux settings for the NCR beamline were commissioned. Three particle flux settings ranging from ~2.4 kHz to ~5.2 MHz were established for seven proton energies below 252.7 MeV. In addition to the particle rate, the spot sizes and beam energies were measured for these settings. Also three low flux settings for 800 MeV protons ranging from ~2 kHz to ~1.3 MHz were commissioned.