Calibration of the RPC charge readout in the ARGO-YBJ experiment

Abstract The charge readout of Resistive Plate Chambers (RPCs) is implemented in the ARGO-YBJ experiment to measure the charged particledensity of the showerfront up to 10 4 /m 2 , enabling the study of the primary cosmic rays with energies in the “knee” region. As the first time for RPCs being used this way, a telescope with RPCs and scintillation detectors is setup to calibrate the number of charged particleshitting a RPC versus its charge readout. Air showerparticles are taken as the calibration beam. The telescope was tested at sea level and then moved to the ARGO-YBJ site for coincident operation with the ARGO-YBJ experiment. The charge readout shows good linearity with the particle densityin the dynamic range (up to 200/m 2 ).