We introduce an AXUV forward modelling tool to aid the interpretation of phenomena from experiments on ASDEX Upgrade (AUG) and to support the validation of plasma modelling. AXUV diodes [1] detect electromagnetic radiation across a wide spectral range, albeit with a non-uniform spectral responsivity. This diagnostic has a significantly higher time resolution ($\sim \mu s$) than foil bolometers ($\sim ms$). It is suitable for examining fast phenomena, such as shattered-pellet injection (SPI)[2,3], during which the radiation localisation and radiated power provide information on the deposition of pellet material. Due to the characteristics and inevitable degradation of AXUV diodes, absolute power measurements are subject to large systematic uncertainties. Additionally, when the emitted spectra are time-varying, the detection efficiency changes throughout the discharge, for example, in neon-doped SPI experiments. These factors motivated the development of a synthetic diagnostic for AUG AXUV cameras in Cherab [4] for two pairs of poloidally displaced cameras, toroidally $\sim$110 degrees apart. The synthetic diagnostic provides a means to advance our understanding of the underlying physics during SPI and of how the diodes measure radiation in these circumstances. The details of the synthetic diagnostics are presented, with applications to AUG SPI simulations performed in JOREK [5,6]. The synthetic signals generated from these simulations are also compared to experimental measurements from the 2022 SPI campaign. Good agreement was found in the time evolution for the high Ne-content (10%) pellet, whereas the low Ne-content (0.17%) case exhibited some significant differences. ### References [1] M. Bernert et al., “Application of AXUV diode detectors at ASDEX Upgrade,” Rev. Sci. Instrum., vol. 85, no. 3, p. 033503, Mar. 2014, doi: 10.1063/1.4867662. [2] M. Dibon et al., “Design of the shattered pellet injection system for ASDEX Upgrade,” Review of Scientific Instruments, vol. 94, no. 4, p. 043504, Apr. 2023, doi: 10.1063/5.0141799. [3] P. Heinrich, “Shattered pellet injection studies at the tokamak ASDEX Upgrade,” PhD, Technical University Munich, Garching bei München, 2025. [4] M. Carr et al., “Towards integrated data analysis of divertor diagnostics with ray-tracing,” presented at the 44th EPS Conference on Plasma Physics, Belfast, Northern Ireland (UK), 2017. [5] W. Tang et al., “Quantitative 3D non-linear simulations of shattered pellet injection in ASDEX Upgrade using JOREK,” Feb. 13, 2026, arXiv: arXiv:2602.12813. doi: 10.48550/arXiv.2602.12813. [6] M. Hoelzl et al., “The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas,” Nucl. Fusion, vol. 61, no. 6, p. 065001, May 2021, doi: 10.1088/1741-4326/abf99f.