In beta -decay experiments on C-9 at CERN/ISOLDE the beta -strength was det
ermined to the ground state, the 12.2 MeV excited state and the Isobaric An
alog State (IAS) at 14.655 MeV in B-9. A large beta -strength asymmetry is
deduced for the mirror transitions of C-9 and Li-9 to states around 12 MeV
excitation energy. A satisfactory description of the three-body decay from
a narrow energy region around the 12.2 MeV resonance is obtained within a s
equential model involving the ground and first-excited states of Li-5 and B
e-8. From the study of angular correlations the spin of the 12.2 MeV state
is determined as 5/2(-). For the first time the population of the IAS is ob
served in beta -decay and new information on the decay of this state is obt
ained. The advantages of a closely packed. highly segmented detector setup
are demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved.