Very recently, string states have been identified for the first time in antiferromagnetic Heisenberg-Ising chain SrCo2V2O8 in longitudinal magnetic fields using high-resolution terahertz spectroscopy. Instead of string states, another exotic excitations called psinon/(anti)psinon pair excitations have also been identified in the critical field regime and both novel excitations can be described by the Bethe ansatz. However, due to the intrinsic limits of the terahertz spectroscopy, the momentum dependences of these novel excitations are still elusive. The primary goal of this proposal is to identify string states and psinon/(anti)psinon pair excitations using inelastic neutron scattering technique. The spin excitation spectrum in the full Brillouin zone would be mapped out and the momentum dependences of the spin excitations would be determined.