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The Λ 9 Li →π − + 9 Be ∗ →π − + p + 8 Li and Λ 9 B →π − + 9 C ∗ →π − + p + 8 B decay modes were investigated. The existence of an isospin - 3 2 state of 9Be, with excitation energy 18.6 ± 0.1 MeV and width Γ ≲ 300 keV has been established. From a reanalysis of European K− Collaboration emulsion data, new values of the binding energies of 9ΛLi and 9ΛB hypernuclei were found as 8.50 ± 0.12 MeV and 8.29 ± 0.18 MeV, respectively.

A study has been made of the decay sequence 12 Λ B → π − + 12 C ∗ → π − + 4 He + 4 He + 4 He . From a comparison of the measured branching ratios to certain states of 12C and the angular correlations observed in their decays with those predicted by Zieminska and Dalitz, it is concluded that the spin of the hypernucleus 12ΛB strongly favours the value of unity.

Kinematic analysis of simple hypernuclear production reactions has produced a sample of hypernuclei of ΛB, ΛC and ΛN with negligible background, and a much smaller sample of ΛBe. The values of the non-mesonic to π− mesonic ratio Q− for the above samples are 5.5 ± 0.5 and 4.3 ± 1.1, respectively. A sub-sample of 11ΛB hypernuclei was separated on the basis of production via an excited state of Λ12C, giving Q− = 4.8 ± 1.1 for Λ11B. Assuming the Fermi gas model is applicable to nuclei of mass A ≈ 11, two independent means of analysis of the non-mesonic decays give values for the Λ-neutron stimulation fraction n of 0.41 ± 0.09 and 0.34 ± 0.07 for hypernuclei of charge 5 ≦ Z ≦ 7.

The evidence concerning the region of the nucleus in which the capture of K − mesons in K mesonic atoms predominantly occurs is re-examined in the light of a recent criticism. It is concluded that capture in the extreme peripheral region where the nuclear density is of the order of 5 per cent of the the central density and the existence of a neutron halo in heavy nuclei remain the most probable interpretation of the available data.