Title: Ce 3$p$ hard x-ray photoelectron spectroscopy study of the topological Kondo insulator CeRu$_4$Sn$_6$,
Abstract: Bulk sensitive hard x-ray photoelectron spectroscopy data of the Ce 3$p$ core
level of CeRu$_4$Sn$_6$ are presented. Using a combination of full multiplet
and configuration iteration model we were able to obtain an accurate lineshape
analysis of the data, thereby taking into account correlations for the strong
plasmon intensities. We conclude that CeRu$_4$Sn$_6$ is a moderately mixed
valence compound with a weight of 8% for the Ce $f^0$ configuration in the
ground state.