Comparison of simulated backgrounds with in-orbit observations for HXI onboard ASO-S

Abstract The Hard X-ray Imager (HXI) payload, a component of China's Advanced Space-based Solar Observatory (ASO-S) satellite, is designed to observe solar X-ray emissions in the 30-200 keV range, with the aim of investigating non-thermal physical processes during solar flares. Before launch, Geant4 simulations were employed to assess the on-orbit background of the HXI instrument, evaluating its performance and potential to achieve its scientific objectives. This study addresses issues identified in previous simulations and conducts further analyses to examine the distribution of background counts across the 99 detectors. The results demonstrate alignment between simulations and observations at low and medium geomagnetic latitudes; however, challenges persist at high geomagnetic latitudes due to limitations in the current albedo photon model. This investigation provides insights into background sources from various particles, enhances understanding of space background characteristics, and offers guidance for background subtraction in imaging processes.