Measurement of the energy distribution in the very forward direction at $13~\mathrm{TeV}$ with CMS

The event-by-event energy deposition into the very forward acceptance, $-6.6<\eta<-5.2$, of CMS is measured and characterized in proton-proton collisions at $13~\mathrm{TeV}$. Data from the electromagnetic and hadronic sections of the CASTOR calorimeter are used for this purpose. The results are corrected to stable particle level and presented independently for the electromagnetic as well as the hadronic component of the hadronic multiparticle production. The data are sensitive to the production of neutral and charged mesons, which is a key ingredient for the modeling of cosmic ray induced extensive air showers at ultra-high energies. The presented data are relevant for the fraction of primary energy converted into secondary muons. Furthermore, the data are sensitive to the characteristics of multi-parton interactions.