Hypernuclear Fine Structure in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">O</mml:mi><mml:mprescripts/><mml:mi>Λ</mml:mi><mml:mn>16</mml:mn></mml:mmultiscripts></mml:math>and the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Λ</mml:mi><mml:mi>N</mml:mi></mml:math>Tensor Interaction

We have observed two gamma-ray transitions in (16)(Lambda)O from the 6.6 MeV excited 1(-)(2) state to both ground-state spin-doublet members (1(-)(1),0(-)) by the (K-,pi(-)gamma) reaction. We have obtained the ground-state doublet spacing to be 26.4+/-1.6(stat)+/-0.5(syst) keV and the excitation energy of the 1(-)(2) state to be 6561.7+/-1.1(stat)+/-1.7(syst) keV. The ground-state doublet spacing provides a small but nonzero strength of the tensor interaction between a Lambda and a nucleon. This is the first experimental result on the LambdaN tensor interaction.