Light output of Double Chooz scintillators for low energy electrons

The energy dependent light output of liquid scintillators used in the Double Chooz experiment was measured for electrons up to 140 keV energy. A new Compton scattering coincidence apparatus was built for this purpose. A detailed study on possible systematic errors was made. We report the experimental results of our investigations and tested them for concordance with the predictions of various models. All models reasonably fit the experimental data after adjusting the respective free parameters. The results were also used to tune the Geant4-based Monte Carlo simulation software which is used in Double Chooz. The experimental data can be described by the simulation choosing an effective value for the Birks parameter