Spectroscopic study of B Λ 10 , C Λ 12 , Si Λ 28 , Y Λ 89 , La Λ 139 , and Pb Λ 208 by the ( π + , K + ) reaction

Hypernuclear mass spectra of ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{10}$B, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{12}$C, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{28}$Si, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{89}$Y, ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{139}$La, and ${\mathrm{}}_{\mathrm{\ensuremath{\Lambda}}}^{208}$Pb were measured by the (${\mathrm{\ensuremath{\pi}}}^{+}$,${\mathit{K}}^{+}$) reaction with an energy resolution of 2 MeV (FWHM). The experiment was carried out with a 1.06 GeV/c ${\mathrm{\ensuremath{\pi}}}^{+}$ beam from the KEK 12-GeV PS and with the superconducting kaon spectrometer (SKS). For light hypernuclei, core-excited states were resolved for the first time. For heavy hypernuclei, peak structure reflecting \ensuremath{\Lambda} shell structure was observed. \textcopyright{} 1996 The American Physical Society.