Measurement of the Fluctuations in the Number of Muons in Extensive Air Showers with the Pierre Auger Observatory
A. Aab, P. Abreu, M. Aglietta, Justin M. Albury, I. Allekotte, A. Almela, Jaime Álvarez-Muñiz, Rafael Alves Batista, Gioacchino Alex Anastasi, L. Anchordoqui, B. Andrada, S. Andringa, C. Aramo, P. R. Araújo Ferreira, H. Asorey, P. Assis, Gualberto Avila, Alina Mihaela Badescu, Alena Bakalová, A. Balaceanu, Felicia Barbato, Ricardo Jorge Barreira Luz, K. H. Becker, Jose A. Bellido, C. Berat, M. E. Bertaina, X. Bertou, Peter L. Biermann, Teresa Bister, J. Biteau, Jiří Blažek, C. Bleve, M. Boháčová, Denise Boncioli, C. Bonifazi, L. Bonneau Arbeletche, Nataliia Borodai, Ana Martina Botti, J. Brack, T. Bretz, F. L. Briechle, P. Buchholz, A. Bueno, S. Buitink, Mario Buscemi, K. S. Caballero‐Mora, Lorenzo Caccianiga, A. Cancio, F. Canfora, I. Caracas, J. M. Carceller, R. Caruso, A. Castellina, F. Catalani, G. Cataldi, Lorenzo Cazon, M. Cerda, J. A. Chinellato, K. Choi, J. Chudoba, L. Chytka, R. W. Clay, A. C. Cobos Cerutti, Roberta Colalillo, A. Coleman, M. R. Coluccia, R. Conceição, Antonio Condorelli, G. Consolati, F. Contreras, Fabio Convenga, C. E. Covault, S. Dasso, K. Daumiller, B. R. Dawson, J. A. Day, R. M. de Almeida, J. de Jesús, S. J. de Jong, G. De Mauro, J. R. T. de Mello Neto, I. De Mitri, J. de Oliveira, Danelise de Oliveira Franco, V. de Souza, Emanuele De Vito, J. Debatin, M. del Río, O. Deligny, H.-P. Dembinski, N. Dhital, Armando di Matteo, C. Dobrigkeit, J. C. D’Olivo, R. C. dos Anjos, M. T. Dova, Jan Ebr, R. Engel, I. Epicoco, M. Erdmann
Abstract
We present the first measurement of the fluctuations in the number of muons in extensive air showers produced by ultrahigh energy cosmic rays. We find that the measured fluctuations are in good agreement with predictions from air shower simulations. This observation provides new insights into the origin of the previously reported deficit of muons in air shower simulations and constrains models of hadronic interactions at ultrahigh energies. Our measurement is compatible with the muon deficit originating from small deviations in the predictions from hadronic interaction models of particle production that accumulate as the showers develop.