Relative measurement and extrapolation of the scintillation quenching factor of α-particles in liquid argon using DEAP-3600 data

The knowledge of scintillation quenching of α α -particles plays a paramount role in understanding α α -induced backgrounds and improving the sensitivity of liquid argon-based direct detection of dark matter experiments. We performed a relative measurement of scintillation quenching in the MeV energy region using radioactive isotopes ( ²²² 222 Rn, ²¹⁸ 218 Po and ²¹⁴ 214 Po isotopes) present in trace amounts in the DEAP-3600 detector and quantified the uncertainty of extrapolating the quenching factor to the low-energy region.