Determination of the proton and alpha-particle light-response functions for the KamLAND, BC-501A and BC-517H liquid scintillators

A cylindrical 5.1 cm×5.1 cm scintillator cell filled with the KamLAND liquid scintillator has been exposed to monoenergetic neutron beams produced via the 2H(d,n)3He reaction to measure the proton light-response function for energies up to 10 MeV. Using Birks’ recipe, the α-particleα-particle light-response function was derived from these data. The same method was applied to the BC-501A and BC-517H liquid scintillators to check on the systematic accuracy of the present data. The proton and α-particleα-particle light-response functions are needed to correct the KamLAND antineutrino prompt energy spectrum for background effects caused by the reaction C13(α,n)O16. Especially, the geo-antineutrino energy regime measured in the KamLAND experiment is contaminated by background events from this reaction.