Measurement of the depth of maximum of air-shower profiles with energies between ${10}^{18.5}$ and ${10}^{20}\mathrm{eV}$ using the surface detector of the Pierre Auger Observatory and deep learning

Journal Article · 12 January 2025 · Physical Review. D.

DOI: https://doi.org/10.1103/PhysRevD.111.022003 · OSTI ID:2499847

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

We report an investigation of the mass composition of cosmic rays with energies from 3 to 100 EeV ( $1\mathrm{EeV}={10}^{18}\mathrm{eV}$ ) using the distributions of the depth of shower maximum $X_{\max }$ . 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 dataset 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 $X_{\max }$ distributions up to 100 EeV. Our findings are threefold: (i) The evolution of the mean logarithmic mass toward a heavier composition with increasing energy can be confirmed and is extended to 100 EeV. (ii) The evolution of the fluctuations of $X_{\max }$ toward a heavier and purer composition with increasing energy can be confirmed with high statistics. We report a rather heavy composition and small fluctuations in $X_{\max }$ at the highest energies. (iii) 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. Published by the American Physical Society 2025

• Research Organization: ABC Federal U.; ASFYON; ASI, Rome; Aachen, Tech. Hochsch.; Adelaide U.; Amsterdam U.; Bath U.; Bonn, Max Planck Inst., Radioastron.; Brussels U., IIHE; Bucharest U.; Bucharest, Inst. Space Science; Buenos Aires, CONICET; CEFET, Rio de Janeiro; CINVESTAV, IPN; Campina Grande Federal U.; Campinas State U.; Case Western Reserve U.; Catania U.; Centro Atomico Bariloche; Charles U.; Chiapas Autonoma U.; Chicago U., EFI; Colorado School of Mines; Colorado State U.; Cracow, INP; Delaware U.; Erlangen - Nuremberg U., ECAP; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Gran Sasso; Granada U.; Hamburg U., Inst. Theor. Phys. II; IASF, Palermo; ICAS, UNSAM, Buenos Aires; IFIR, Rosario; IFMT, Caceres; IJCLab, Orsay; INFN, Aquila; INFN, Catania; INFN, Lecce; INFN, Milan; INFN, Naples; INFN, Rome; INFN, Rome2; INFN, Turin; ITeDA, Buenos Aires; IUF, Paris; KIT, Karlsruhe, ETP; KIT, Karlsruhe, IAP; KIT, Karlsruhe, IPE; Kapteyn Astron. Inst., Groningen; L'Aquila U.; LIP, Lisbon; LPNHE, Paris; LPSC, Grenoble; La Plata U.; Leeds U.; Lehman Coll.; Lodz U.; Medellin U.; Messina U.; Mexico U., ICN; Michigan Tech. U.; Milan U.; Milan, Polytech.; NASA, Goddard; NIKHEF, Amsterdam; Naples U.; Natl. Tech. U., San Rafael; New York U. (main); Nijmegen U., IMAPP; Nova Gorica U.; OATo, Turin; Osaka City U.; Palacky U.; Palermo U.; Penn State U.; Pierre Auger Observ.; Prague, Inst. Phys.; Puebla U., Inst. Fis.; Rio de Janeiro Federal U.; Rio de Janeiro, CBPF; Rome U., Tor Vergata; Salento U.; San Augustin Natl. U., Arequipa; Santander Industrial U.; Santiago de Compostela U., IGFAE; Sao Paulo U.; Sao Paulo U., Sao Carlos; Siegen U.; Stefan Inst., Ljubljana; Turin U.; U. Buenos Aires; U. Sao Paulo (main); U. Tech. Natl., Argentina; UEFS, Feira de Santana; UFOP, Ouro Preto; USTC, Hefei; Vrije U., Amsterdam; Vrije U., Brussels; Wisconsin U., Madison; Wuppertal U.
• Sponsoring Organization: US Department of Energy; USDOE
• Grant/Contract Number: 89243024CSC000002; AC02-07CH11359; FG02-99ER41107; SC0011689
• OSTI ID: 2499847
• Report Number(s): FERMILAB-PUB-24-0615-PPD-TD; 022003
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 2 Vol. 111; ISSN PRVDAQ; ISSN 2470-0010
• Publisher: American Physical SocietyCopyright Statement
• Country of Publication: United States
• Language: English