Effect of Low Electric Fields on Alpha Scintillation Light Yield in   Liquid Argon
  Measurements were made of scintillation light yield of alpha particles from the $^{222}$Rn decay chain within the DarkSide-50 liquid argon time projection chamber. The light yield was found to increase as the applied electric field increased, with alphas in a 200 V/cm electric field exhibiting a 2% increase in light yield compared to alphas in no field. 
P. Agnes, I. F. M. Albuquerque, T. Alexander, A. K. Alton, D. M.   Asner, H. O. Back, B. Baldin, K. Biery, V. Bocci, G. Bonf...
physics.ins-det nucl-ex