Observation ofΛ-Hypernuclei in the ReactionC12(π+, K+)CΛ12

The observation of $\Lambda$-hypernuclear levels in ${}_{\Lambda }{}^{12}{}_{}{}^{}\mathrm{C}$ by associated production through the (${\pi }^{+}, K^{+}$) reaction is reported. The ${}_{\Lambda }{}^{12}{}_{}{}^{}\mathrm{C}$ excitation-energy spectra were recorded at laboratory scattering angles of 5.6°, 10.3°, and 15.2°. They show two major peaks—one attributed to the ground state, and one about 11 MeV higher. These results are compared to the strangeness-exchanging ($K^{-}, {\pi }^{-}$) reaction. The measured cross sections are compared to relativistic distorted-wave Born-approximation calculations.