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Background: The extremely fast delivery of doses with ultra high dose rate (UHDR) beams necessitates the investigation of novel approaches for real‐time dosimetry and beam monitoring. This aspect is fundamental in the perspective of the clinical application of FLASH radiotherapy (FLASH‐RT), as conventional dosimeters tend to saturate at such extreme dose rates. Purpose: This study aims to experimentally characterize newly developed silicon carbide (SiC) detectors of various active volumes at UHDRs and systematically assesses their response to establish their suitability for dosimetry in FLASH‐RT. Methods: SiC PiN junction detectors, recently realized and provided by STLab company, with different active areas (ranging from 4.5 to 10 mm2) and thicknesses (10–20 µm), were irradiated using 9 MeV UHDR pulsed electron beams accelerated by the ElectronFLASH linac at the Centro Pisano for FLASH Radiotherapy (CPFR). The linearity of the SiC response as a function of the delivered dose per pulse (DPP), which in turn corresponds to a specific instantaneous dose rate, was studied under various experimental conditions by measuring the produced charge within the SiC active layer with an electrometer. Due to the extremely high peak currents, an external customized electronic RC circuit was built and used in conjunction with the electrometer to avoid saturation. Results: The study revealed a linear response for the different SiC detectors employed up to 21 Gy/pulse for SiC detectors with 4.5 mm2/10 µm active area and thickness. These values correspond to a maximum instantaneous dose rate of 5.5 MGy/s and are indicative of the maximum achievable monitored DPP and instantaneous dose rate of the linac used during the measurements. Conclusions: The results clearly demonstrate that the developed devices exhibit a dose‐rate independent response even under extreme instantaneous dose rates and dose per pulse values. A systematic study of the SiC response was also performed as a function of the applied voltage bias, demonstrating the reliability of these dosimeters with UHDR also without any applied voltage. This demonstrates the great potential of SiC detectors for accurate dosimetry in the context of FLASH‐RT. [ABSTRACT FROM AUTHOR]

For many synchrotron radiation experiments, it is critical to perform continuous, real‐time monitoring of the X‐ray flux for normalization and stabilization purposes. Traditional transmission‐mode monitors included metal mesh foils and ionization chambers, which suffered from low signal stability and size constraints. Solid‐state detectors are now considered superior alternatives for many applications, offering appealing features like compactness and signal stability. However, silicon‐based detectors suffer from poor radiation resistance, and diamond detectors are limited in scalability and are expensive to produce. Silicon carbide (SiC) has recently emerged as an alternative to both materials, offering a high‐quality mature semiconductor with high thermal conductivity and radiation hardness. This study focuses on a systematic exploration of the SiC `free‐standing membrane' devices developed by SenSiC GmbH. In particular, we performed in‐depth sensor‐response analysis with photon energies ranging from tender (1.75 keV) to hard (10 keV) X‐rays at the Four‐Crystal Monochromator beamline in the PTB laboratory at the synchrotron radiation facility BESSY II, studying uniformity of transmission and responsivity compared with the state‐of‐the‐art beam monitors. Furthermore, we theoretically evaluated the expected signal in different regions of the sensors, also taking into account the effect of charge diffusion from the SiC substrate in the case of the not‐carved region. [ABSTRACT FROM AUTHOR]