Dosimetry at ultra-high instantaneous dose rates with SiC diodes in a photoinjector based electron accelerator

We report for the first time a methodology for the dosimetric characterization of the PHIL (Photo Injector at Laboratoire de l’accélérateur linéaire) electron accelerator beamline using a variety of new radiation-hard silicon carbide (SiC)–based detectors developed for Ultra-High Dose Rate (UHDR) applications, including single diodes (0.6–2.2 mm) and a 4 × 4 pixel array. The 7 MeV electrons were pulsed in bunches on ps scale in rates of 10 Hz. Although the maximum measured average dose rate ( ∼ 1.2 Gy/s) remains below the UHDR threshold for triggering the biological FLASH effect under UHDR ( > 40 Gy/s), the instantaneous dose rates are on the order of 1 0 10 Gy/s. The SiC detectors exhibited linear response over the beam charge range of 2–36 pC per bunch enabling also beam profiling with these detectors. No saturation effects were observed in any of the SiC devices, whereas instantaneous dose rates far exceeded those used in FLASH studies due to the extremely short bunch duration ( ∼ 20 ps). These results constitute the highest instantaneous dose rate measured with SiC dosimeters reported to date, which validate their suitability as dosimeter for future accelerator developments with capacities beyond current UHDRs used in FLASH therapy. This work marks a substantial methodological advance for accelerators with extremely short picosecond electron bunches and RF-induced parasitic signals.