Measurement of α-particle quenching in LAB based scintillator in independent small-scale experiments

Abstract

The (Formula presented.) -particle light response of liquid scintillators based on linear alkylbenzene (LAB) has been measured with three different experimental approaches. In the first approach, (Formula presented.) -particles were produced in the scintillator via (Formula presented.) C(n, (Formula presented.)) (Formula presented.) Be reactions. In the second approach, the scintillator was loaded with 2 % of (Formula presented.) Sm providing an (Formula presented.) -emitter, (Formula presented.) Sm, as an internal source. In the third approach, a scintillator flask was deployed into the water-filled SNO+ detector and the radioactive contaminants (Formula presented.) Rn, (Formula presented.) Po and (Formula presented.) Po provided the (Formula presented.) -particle signal. The behavior of the observed (Formula presented.) -particle light outputs are in agreement with each case successfully described by Birks’ law. The resulting Birks parameter kB ranges from (Formula presented.) to (Formula presented.)  cm/MeV. In the first approach, the (Formula presented.) -particle light response was measured simultaneously with the light response of recoil protons produced via neutron–proton elastic scattering. This enabled a first time a direct comparison of kB describing the proton and the (Formula presented.) -particle response of LAB based scintillator. The observed kB values describing the two light response functions deviate by more than (Formula presented.). The presented results are valuable for all current and future detectors, using LAB based scintillator as target, since they depend on an accurate knowledge of the scintillator response to different particles.