  Recent progress in the development of novel organic scintillators
necessitates modern characterization capabilities. As the primary means of
energy deposition by neutrons in these materials is n-p elastic scattering,
knowledge of the proton light yield is paramount. This work establishes a new
model-independent method to continuously measure proton light yield in organic
scintillators over a broad energy range. Using a deuteron breakup neutron
source at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory and an
array of organic scintillators, the proton light yield of EJ-301 and EJ-309,
commercially available organic liquid scintillators from Eljen Technology, were
measured via a double time-of-flight technique. The light yield was determined
using a kinematically over-constrained system in the proton energy range of
1-20 MeV. The effect of pulse integration length on the magnitude and shape of
the proton light yield relation was also explored. This work enables accurate
simulation of the performance of advanced neutron detectors and supports the
development of next-generation neutron imaging systems.
