Measurement of the Depth of Maximum of Air-Shower Profiles with energies between $\mathbf{10^{18.5}}$ and $\mathbf{10^{20}}$ eV using the Surface Detector of the Pierre Auger Observatory and Deep Learning
Creators: name: The Pierre Auger Collaboration
name: Halim, A. Abdul
name: Abreu, P.
name: Aglietta, M.
name: Allekotte, I.
name: Cheminant, K. Almeida
name: Almela, A.
name: Aloisio, R.
name: Alvarez-Muñiz, J.
name: Yebra, J. Ammerman
name: Anastasi, G. A.
name: Anchordoqui, L.
name: Andrada, B.
name: Dourado, L. Andrade
name: Andringa, S.
name: Apollonio, L.
name: Aramo, C.
name: Ferreira, P. R. Araújo
name: Arnone, E.
name: Velázquez, J. C. Arteaga
name: Assis, P.
name: Avila, G.
name: Avocone, E.
name: Bakalova, A.
name: Barbato, F.
name: Mocellin, A. Bartz
name: Berat, C.
name: Bertaina, M. E.
name: Bhatta, G.
name: Bianciotto, M.
name: Biermann, P. L.
name: Binet, V.
name: Bismark, K.
name: Bister, T.
name: Biteau, J.
name: Blazek, J.
name: Bleve, C.
name: Blümer, J.
name: Boháčová, M.
name: Boncioli, D.
name: Bonifazi, C.
name: Arbeletche, L. Bonneau
name: Borodai, N.
name: Brack, J.
name: Orchera, P. G. Brichetto
name: Briechle, F. L.
name: Bueno, A.
name: Buitink, S.
name: Buscemi, M.
name: Büsken, M.
name: Bwembya, A.
name: Caballero-Mora, K. S.
name: Cabana-Freire, S.
name: Caccianiga, L.
name: Campuzano, F.
name: Caruso, R.
name: Castellina, A.
name: Catalani, F.
name: Cataldi, G.
name: Cazon, L.
name: Cerda, M.
name: Čermáková, B.
name: Cermenati, A.
name: Chinellato, J. A.
name: Chudoba, J.
name: Chytka, L.
name: Clay, R. W.
name: Cerutti, A. C. Cobos
name: Colalillo, R.
name: Coluccia, M. R.
name: Conceição, R.
name: Condorelli, A.
name: Consolati, G.
name: Conte, M.
name: Convenga, F.
name: Santos, D. Correia dos
name: Costa, P. J.
name: Covault, C. E.
name: Cristinziani, M.
name: Sanchez, C. S. Cruz
name: Dasso, S.
name: Daumiller, K.
name: Dawson, B. R.
name: de Almeida, R. M.
name: de Errico, B.
name: de Jesús, J.
name: de Jong, S. J.
name: Neto, J. R. T. de Mello
name: De Mitri, I.
name: de Oliveira, J.
name: Franco, D. de Oliveira
name: de Palma, F.
name: de Souza, V.
name: De Vito, E.
name: Del Popolo, A.
name: Deligny, O.
name: Denner, N.
name: Deval, L.
name: di Matteo, A.
name: do, J. A.
name: Dobre, M.
name: Dobrigkeit, C.
name: D'Olivo, J. C.
name: Mendes, L. M. Domingues
name: Dorosti, Q.
name: Anjos, J. C. dos
name: Anjos, R. C. dos
name: Ebr, J.
name: Ellwanger, F.
name: Emam, M.
name: Engel, R.
name: Epicoco, I.
name: Erdmann, M.
name: Etchegoyen, A.
name: Evoli, C.
name: Falcke, H.
name: Farrar, G.
name: Fauth, A. C.
name: Fehler, T.
name: Feldbusch, F.
name: Fenu, F.
name: Fernandes, A.
name: Fick, B.
name: Figueira, J. M.
name: Filip, P.
name: Filipčič, A.
name: Fitoussi, T.
name: Flaggs, B.
name: Fodran, T.
name: Fujii, T.
name: Fuster, A.
name: Galea, C.
name: García, B.
name: Gaudu, C.
name: Gherghel-Lascu, A.
name: Ghia, P. L.
name: Giaccari, U.
name: Glombitza, J.
name: Gobbi, F.
name: Gollan, F.
name: Golup, G.
name: Berisso, M. Gómez
name: Vitale, P. F. Gómez
name: Gongora, J. P.
name: González, J. M.
name: González, N.
name: Góra, D.
name: Gorgi, A.
name: Gottowik, M.
name: Guarino, F.
name: Guedes, G. P.
name: Guido, E.
name: Gülzow, L.
name: Hahn, S.
name: Hamal, P.
name: Hampel, M. R.
name: Hansen, P.
name: Harari, D.
name: Harvey, V. M.
name: Haungs, A.
name: Hebbeker, T.
name: Hojvat, C.
name: Hörandel, J. R.
name: Horvath, P.
name: Hrabovský, M.
name: Huege, T.
name: Insolia, A.
name: Isar, P. G.
name: Janecek, P.
name: Jilek, V.
name: Johnsen, J. A.
name: Jurysek, J.
name: Kampert, K. -H.
name: Keilhauer, B.
name: Khakurdikar, A.
name: Covilakam, V. V. Kizakke
name: Klages, H. O.
name: Kleifges, M.
name: Knapp, F.
name: Köhler, J.
name: Krieger, F.
name: Kunka, N.
name: Lago, B. L.
name: Langner, N.
name: de Oliveira, M. A. Leigui
name: Lema-Capeans, Y.
name: Letessier-Selvon, A.
name: Lhenry-Yvon, I.
name: Lopes, L.
name: Lu, L.
name: Luce, Q.
name: Lundquist, J. P.
name: Payeras, A. Machado
name: Majercakova, M.
name: Mandat, D.
name: Manning, B. C.
name: Mantsch, P.
name: Mariani, F. M.
name: Mariazzi, A. G.
name: Mariş, I. C.
name: Marsella, G.
name: Martello, D.
name: Martinelli, S.
name: Bravo, O. Martínez
name: Martins, M. A.
name: Mathes, H. -J.
name: Matthews, J.
name: Matthiae, G.
name: Mayotte, E.
name: Mayotte, S.
name: Mazur, P. O.
name: Medina-Tanco, G.
name: Meinert, J.
name: Melo, D.
name: Menshikov, A.
name: Merx, C.
name: Michal, S.
name: Micheletti, M. I.
name: Miramonti, L.
name: Mollerach, S.
name: Montanet, F.
name: Morejon, L.
name: Mulrey, K.
name: Mussa, R.
name: Namasaka, W. M.
name: Negi, S.
name: Nellen, L.
name: Nguyen, K.
name: Nicora, G.
name: Niechciol, M.
name: Nitz, D.
name: Nosek, D.
name: Novotny, V.
name: Nožka, L.
name: Nucita, A.
name: Núñez, L. A.
name: Oliveira, C.
name: Palatka, M.
name: Pallotta, J.
name: Panja, S.
name: Parente, G.
name: Paulsen, T.
name: Pawlowsky, J.
name: Pech, M.
name: Pękala, J.
name: Pelayo, R.
name: Pelgrims, V.
name: Pereira, L. A. S.
name: Martins, E. E. Pereira
name: Bertolli, C. Pérez
name: Perrone, L.
name: Petrera, S.
name: Petrucci, C.
name: Pierog, T.
name: Pimenta, M.
name: Platino, M.
name: Pont, B.
name: Pothast, M.
name: Shahvar, M. Pourmohammad
name: Privitera, P.
name: Prouza, M.
name: Querchfeld, S.
name: Rautenberg, J.
name: Ravignani, D.
name: Akim, J. V. Reginatto
name: Reininghaus, M.
name: Reuzki, A.
name: Ridky, J.
name: Riehn, F.
name: Risse, M.
name: Rizi, V.
name: de Carvalho, W. Rodrigues
name: Rodriguez, E.
name: Rojo, J. Rodriguez
name: Roncoroni, M. J.
name: Rossoni, S.
name: Roth, M.
name: Roulet, E.
name: Rovero, A. C.
name: Saftoiu, A.
name: Saharan, M.
name: Salamida, F.
name: Salazar, H.
name: Salina, G.
name: Gomez, J. D. Sanabria
name: Sánchez, F.
name: Santos, E. M.
name: Santos, E.
name: Sarazin, F.
name: Sarmento, R.
name: Sato, R.
name: Savina, P.
name: Schäfer, C. M.
name: Scherini, V.
name: Schieler, H.
name: Schimassek, M.
name: Schimp, M.
name: Schmidt, D.
name: Scholten, O.
name: Schoorlemmer, H.
name: Schovánek, P.
name: Schröder, F. G.
name: Schulte, J.
name: Schulz, T.
name: Sciutto, S. J.
name: Scornavacche, M.
name: Sedoski, A.
name: Segreto, A.
name: Sehgal, S.
name: Shivashankara, S. U.
name: Sigl, G.
name: Simkova, K.
name: Simon, F.
name: Smau, R.
name: Šmída, R.
name: Sommers, P.
name: Squartini, R.
name: Stadelmaier, M.
name: Stanič, S.
name: Stasielak, J.
name: Stassi, P.
name: Strähnz, S.
name: Straub, M.
name: Suomijärvi, T.
name: Supanitsky, A. D.
name: Svozilikova, Z.
name: Szadkowski, Z.
name: Tairli, F.
name: Tapia, A.
name: Taricco, C.
name: Timmermans, C.
name: Tkachenko, O.
name: Tobiska, P.
name: Peixoto, C. J. Todero
name: Tomé, B.
name: Torrès, Z.
name: Travaini, A.
name: Travnicek, P.
name: Tueros, M.
name: Unger, M.
name: Uzeiroska, R.
name: Vaclavek, L.
name: Vacula, M.
name: Galicia, J. F. Valdés
name: Valore, L.
name: Varela, E.
name: Vašíčková, V.
name: Vásquez-Ramírez, A.
name: Veberič, D.
name: Quispe, I. D. Vergara
name: Verzi, V.
name: Vicha, J.
name: Vink, J.
name: Vorobiov, S.
name: Watanabe, C.
name: Watson, A. A.
name: Weindl, A.
name: Wiencke, L.
name: Wilczyński, H.
name: Wittkowski, D.
name: Wundheiler, B.
name: Yue, B.
name: Yushkov, A.
name: Zapparrata, O.
name: Zas, E.
name: Zavrtanik, D.
name: Zavrtanik, M.
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report an investigation of the mass composition of cosmic rays with energies from 3 to 100 EeV (1 EeV=$10^{18}$ eV) using the distributions of the depth of shower maximum $X_\mathrm{max}$. The analysis relies on ${\sim}50,000$ events recorded by the Surface Detector of the Pierre Auger Observatory and a deep-learning-based reconstruction algorithm. Above energies of 5 EeV, the data set offers a 10-fold increase in statistics with respect to fluorescence measurements at the Observatory. After cross-calibration using the Fluorescence Detector, this enables the first measurement of the evolution of the mean and the standard deviation of the $X_\mathrm{max}$ distributions up to 100 EeV. Our findings are threefold:
 (1.) The evolution of the mean logarithmic mass towards a heavier composition with increasing energy can be confirmed and is extended to 100 EeV.
 (2.) The evolution of the fluctuations of $X_\mathrm{max}$ towards a heavier and purer composition with increasing energy can be confirmed with high statistics. We report a rather heavy composition and small fluctuations in $X_\mathrm{max}$ at the highest energies.
 (3.) We find indications for a characteristic structure beyond a constant change in the mean logarithmic mass, featuring three breaks that are observed in proximity to the ankle, instep, and suppression features in the energy spectrum.
description: Version accepted for publication in Phys. Rev. D, 29 pages, 19 figures, 5 tables