Multi-particle States in Spin-1 Chain System CsNiCl3
  A continuum of magnetic states has been observed by neutron scattering from the spin-1 chain compound CsNiCl3 in its disordered gapped one-dimensional phase. Results using both triple-axis and time-of-flight spectrometers show that around the antiferromagnetic point Qc=pi, the continuum lies higher in energy than the Haldane gapped excitations. At 6K the integrated intensity of the continuum is about 12(2)% of the total spectral weight. This result is considerably larger than the 1-3% weight predicted by the non-linear sigma model for the 3-particle continuum. 
M. Kenzelmann, R.A. Cowley, W.J.L. Buyers, R. Coldea, J.S. Gardner, M.   Enderle, D.F. McMorrow, S.M. Bennington