Gamma-ray Spectroscopy of 12C Via the (π+,k+) Reaction

A γ-ray spectroscopy experiment via the C12(π+,K+) reaction was carried out at KEK-PS in 2005. The K6 beam line and Superconducting Kaon Spectrometer (SKS) were employed to obtain a missing mass spectrum for 12ΛC. An upgraded germanium detector array, Hyperball2, was introduced to detect γ rays emitted from hypernuclei in coincidence with the (π+,K+) reaction. As a result of further analysis, a γ-ray peak at 6048 keV (preliminary) was newly observed and assigned as the M1 transition from the 6-MeV excited state to the ground state.