Calibration of the RPC charge readout in the ARGO-YBJ experiment with the iso-gradient method

B. Bartoli;P. Bernardini;X.J. Bi;P. Branchini;A. Budano;P. Camarri;Z. Cao;R. Cardarelli;S. Catalanotti;S.Z. Chen;T.L. Chen;P. Creti;S.W. Cui;B.Z. Dai;A. D׳Amone; Danzengluobu;I. De Mitri;B. D׳Ettorre Piazzoli;T. Di Girolamo;G. Di Sciascio;C.F. Feng;Zhaoyang Feng;Zhenyong Feng;Q.B. Gou;Y.Q. Guo;H.H. He;Haibing Hu;Hongbo Hu;M. Iacovacci;R. Iuppa;H.Y. Jia; Labaciren;H.J. Li;G. Liguori;C. Liu;J. Liu;M.Y. Liu;H. Lu;L.L. Ma;X.H. Ma;G. Mancarella;S.M. Mari;G. Marsella;D. Martello;S. Mastroianni;P. Montini;C.C. Ning;M. Panareo;L. Perrone;P. Pistilli;F. Ruggieri;P. Salvini;R. Santonico;P.R. Shen;X.D. Sheng;F. Shi;A. Surdo;Y.H. Tan;P. Vallania;S. Vernetto;C. Vigorito;H. Wang;C.Y. Wu;H.R. Wu;L. Xue;Q.Y. Yang;X.C. Yang;Z.G. Yao;A.F. Yuan;M. Zha;H.M. Zhang;L. Zhang;X.Y. Zhang;Y. Zhang;J. Zhao; Zhaxiciren; Zhaxisangzhu;X.X. Zhou;F.R. Zhu;Q.Q. Zhu;G. Zizzi