Velocity selector is a key component of small angle neutron scattering instrument

and single wavelength neutron beam of small spectral width can be acquired by a velocity selector.In this work

a rotor-type velocity selector was simulated using the Vitess code to optimize design parameters of the velocity selector for certain experimental requirement.Spectral characteristic of the selected neutrons was analyzed

and it was found that divergence of the incident neutron beam and tilt angle of the rotor affected the spectral characteristic of neutron beam markedly.