In this paper, we present the first tests performed after the full installation of the SIDDHARTA-2 experimental apparatus on the Interaction Region of the DA{\Phi}NE collider at the INFN National Laboratories of Frascati. Before starting the first measurement of the kaonic deuterium 2p{\rightarrow}1s transition, accurate evaluation of the background rejection. mainly achieved with the Kaon Trigger system, was required. This run, performed in the period 04-26/05/2022 with a 4 He gaseous target, confirmed the 10^5 rejection factor obtained with a reduced version of the setup and different machine conditions in 2021. This important outcome motivated the filling of the target cell with deuterium and the starting of the measurement campaign of the kaonic deuterium 2p{\rightarrow}1s transition.
@article{arxiv.2208.03422,
title = {First tests of the full SIDDHARTA-2 experimental apparatus with a 4 He gaseous target},
author = {A. Scordo and C. Amsler and M. Bazzi and D. Bosnar and M. Bragadireanu and M. Cargnelli and M. Carminati and A. Clozza and G. Deda and L. De Paolis and R. Del Grande and L. Fabbietti and C. Fiorini and C. Guaraldo and M. Iliescu and M. Iwasaki and A. Khreptak and P. King and P. Levi Sandri and S. Manti and J. Marton and M. Miliucci and P. Moskal and F. Napolitano and S. Niedźwiecki and H. Ohnishi and K. Piscicchia and Y. Sada and F. Sgaramella and H. Shi and M. Silarski and D. L. Sirghi and F. Sirghi and M. Skurzok and A. Spallone and K. Toho and M. Tüchler and O. Vazquez Doce and C. Yoshida and J. Zmeskal and C. Curceanu},
journal= {arXiv preprint arXiv:2208.03422},
year = {2022}
}