Structure of a Λ-hypernucleus Λ89Y measured with the SKS spectrometer Original Research Article

We have measured an excitation energy spectrum of a Λ-hypernucleus Λ89Y via the (π+, K+) reaction by using the SKS spectrometer at KEK. The best quality data with the energy resolution of 1.63 MeV(FWHM) was obtained in the highest statistics so far. In the spectrum, we can find a splitting of the f-orbital of a Λ particle with the separation of 1.6±0.15 MeV(statistical error only), which may be attributed to the spin-orbit splitting.