Characterization of the SIDDHARTA-2 luminosity monitor

A luminosity monitor, based on plastic scintillator detectors, has been developed for the SIDDHARTA-2 experiment aiming to perform high precision measurements of kaonic atoms and was installed in 2020 on the DA$\Phi$NE $e^{+}{e}^{-}$ collider at LNF (Laboratori Nazionali di Frascati, INFN). The main goal of this system is to provide the instantaneous and integrated luminosity of the DA$\Phi$NE facility by measuring the rate of K${}^{+}$K${}^{-}$ correlated pairs emitted by the $\varphi$ meson decay. This task requires an accurate timing of the DAQ signals, as well as timing resolution below 1 ns, in order to disentangle the K${}^{\pm }$ signals from the background minimum ionizing particles (MIPs) produced during the $e^{+}{e}^{-}$ collisions at DA$\Phi$NE. In this paper the luminosity monitor concept as well as its laboratory characterization and the first results inside DA$\Phi$NE are presented.