Correlation between cosmic ray flux and electric atmospheric field variations with the ARGO-YBJ experiment

ARGO-YBJ is an extensive air shower detector located at Yangbajing (Tibet, China) at 4300 m a.s.l.. It is made by a full coverage carpet plus a guard ring (total surface ∼6700 m2) of Resistive Plate Chambers grouped into 153 units called clusters. The experiment has two different operation modes: in scaler mode the detector records the number of events with particle multiplicity ≥1, ≥2, ≥3, ≥4 over each cluster (reaching an energy threshold of a few GeV), while in shower mode the coordinates and arrival time of each particle are recorded for a complete shower reconstruction at an energy threshold of a few hundred GeV. In this paper the scaler mode counting rate variations during thunderstorms in the summer 2011 and 2012 have been studied. A strong correlation between the counting rate variations and the atmospheric electric field strength has been found.