Shake-up photoemission delay in Neon*

In the ionization of an atom, electrons emerge from different shells with different delays. A longstanding controversy surrounding the measured ($21\pm5$~as at 105~eV) and computed ($\leq 10$~as) time delay difference between the $2s$- and $2p$-shell photoemission from neon [1] has been explained in a recent experimental work [2]. Shake-up channels, which were not resolved in [1], were responsible for the discrepancy between theoretical calculations and the experimental data. This new finding, however, still awaits quantitative theoretical confirmation. In particular, it is still to be determined whether other channels beyond the one identified as being responsible for the measurement bias, might also contribute. In this work, we report advances of a theoretical study conducted with the \footnotesize\textsc{NEWSTOCK} {\it ab initio} method to analyze and quantify the effect of shake-up channels above 70~eV photon energy in neon. [1] M. Sch\"{u}ltze {\it et al.} Science {\bf 328} 1658 (2010), [2] M. Isinger {\it et al.} Science {\bf 358} 893 (2017).