  Knowledge of the neutron light-yield response is crucial to the understanding
of scintillator-based neutron detectors. In this work, neutrons from 2--6 MeV
have been used to study the scintillation light-yield response of the liquid
scintillators NE 213A, EJ 305, EJ 331 and EJ 321P using event-by-event waveform
digitization. Energy calibration was performed using a GEANT model to locate
the edge positions of the Compton distributions produced by gamma-ray sources.
The simulated light yield for neutrons from a PuBe source was compared to
measured recoil proton distributions, where neutron energy was selected by
time-of-flight. This resulted in an energy-dependent Birks parametrization to
characterize the non-linear response to the lower energy neutrons. The NE 213A
and EJ 305 results agree very well with existing data and are reproduced nicely
by the simulation. New results for EJ 331 and EJ 321P, where the simulation
also reproduces the data well, are presented.
