In this paper we present the results of a new kaonic helium-4 measurement with a 1.37 g/l gaseous target by the SIDDHARTA-2 experiment at the DA{\Phi}NE collider. We measured, for the first time, the energies and yields of three transitions belonging to the Mseries. Moreover, we improved by a factor about three, the statistical precision of the 2p level energy shift and width induced by the strong interaction, obtaining the most precise measurement for gaseous kaonic helium, and measured the yield of the L{\alpha} transition at the employed density, providing a new experimental input to investigate the density dependence of kaonic atoms transitions yield.
@article{arxiv.2310.20584,
title = {First measurement of kaonic helium-4 M-series transitions},
author = {F Sgaramella and D Sirghi and L Abbene and F Artibani and M Bazzi and D Bosnar and M Bragadireanu and A Buttacavoli and M Cargnelli and M Carminati and A Clozza and F Clozza and G Deda and R Del Grande and L De Paolis and K Dulski and L Fabbietti and C Fiorini and I Friscic and C Guaraldo and M Iliescu and M Iwasaki and A Khreptak and S Manti and J Marton and M Miliucci and P Moskal and F Napolitano and S Niedzwiecki and H Ohnishi and K Piscicchia and F Principato and A Scordo and M Silarski and F Sirghi and M Skurzok and A Spallone and K Toho and M Tuchler and O Vazquez Doce and C Yoshida and J Zmeskal and C Curceanu},
journal= {arXiv preprint arXiv:2310.20584},
year = {2023}
}