Search for the η-mesic Helium bound state with the WASA-at-COSY facility

Abstract

We performed a search for 4He-η bound state with high statistics and high acceptance with the WASA-at-COSY facility using a ramped beam technique. The signature of η-mesic nuclei is searched for in dd → 3Henπ0 and dd → 3Hepπ− reactions by the measurement of the excitation functions in the vicinity of the η production threshold. This paper presents the experimental method and the preliminary results of the data analysis for dd → 3Henπ0 process.