## 1 _Article_
In [15], a new method has been developed to experimentally determine the saturation factor \(\mathbf{k_{sat}}\) for the standard ionization chambers commercially available as PTW Advanced Markus Chamber, under low-energy electron beam irradiation. The free electron fraction contribution is retrieved to calculate the \(\mathbf{k_{sat}}\) for doses per pulse up to 0.5 Gy/pulse. For doses per pulse higher than 1 Gy/pulse, the huge charge produced in the small active volume modifies the externally applied electric field so that, in some points, the electric field can reach extremely high values and in other points null values leading to a total ion recombination. In order to solve the issue related to ion recombination occurring at high dose per pulse, alternative geometric configurations have been investigated in ultrathin, plane-parallel chambers with a 0.27 mm gap studied in [14] that show a linear response up to large doses per pulse (12 Gy/pulse), demonstrating how ultrathin gas ionization chambers could be a promising solution for secondary standard dosimetry at UHDR. An alternative approach has also been investigated in [17], proposing a new conceptual design of a gas-filled ionization chamber that minimizes the ion recombination. Dose rate independent passive dosimeters, such as radiochromic films (RCFs) and alanine detectors, are currently used as references in UHDR experiments, but the dose determination is typically time consuming and requires post-irradiation analysis processing, which makes them unsuitable as the reference dosimeters for clinical quality assurance (QA) assessment in the perspective of clinical transition. On the other hand, solid-state detectors have recently been investigated as valuable alternative devices for real-time active measurement for both relative and absolute dosimetry and for beam monitoring [10; 18]. In particular, newly designed diamond Schottky diode detectors have been produced at Rome Tor Vergata University in cooperation with PTW Freiburg and have been demonstrated to be linear with doses per pulse up to 12.5 Gy/pulse under UHDR electron beams [18]. Among solid-state base detectors, thanks to its intrinsic characteristics, Silicon Carbide (SiC) detectors have shown promising performances and represent a good compromise between the maturity of Silicon detector development and the robustness of diamonds, allowing for large areas and high applied voltages. For instance, the larger bandgap and e-h pair production energy of SiC compared to Silicon confers a high radiation hardness that makes them definitively more suitable for applications with high intense beam current, as in the case of UHDR beams. On the other hand, a lower value of the e-h pair production energy with respect to the diamond, as shown in Table 1, makes them more sensitive, leading to an expected higher signal-to-noise ratio. The response of novel, ultrathin SiC detectors, developed thanks to a collaboration between the INFN-CT and ST-Lab startup, was studied through simulations and through experimental characterization with low energy UHDR electron beams. First promising results obtained with low energy electron beams accelerated by a dedicated ElectronFLASH LINAC and developed by the SIT-Sordina company for FLASH-RT research studies are shown in this work, aiming at establishing this technology for beam monitoring and dosimetry of UHDR beams for FLASH radiotherapy.