The SIDDHARTA-2 experiment for high precision kaonic atoms X-ray spectroscopy at DAΦNE

High precision X-ray spectroscopy of light kaonic atoms provides valuable information on kaon-nucleus interaction at threshold, allowing to investigate the strong interaction in the strangeness sector at the low-energy frontier. The SIDDHARTA-2 experiment at the DAΦNE collider of INFN-LNF is performing the challenging measurement of the kaonic deuterium 2p→1 s transition which together with the kaonic hydrogen measurement performed by SIDDHARTA, will allow to extract the isospin-dependent antikaon-nucleon scattering lengths. To achieve this goal, the optimization of the setup to maximize the signal over background ratio is a crucial step. This paper presents the SIDDHARTA-2 experiment and its optimization through the first observation of kaonic neon transitions. The excellent electromagnetic background reduction factor (∼ 104) paves the way not only to the measurement of kaonic deuterium, but also to a new era of selected kaonic atom measurements along the periodic table.