@misc{10481/103843,
year = {2025},
month = {1},
url = {https://hdl.handle.net/10481/103843},
abstract = {We report an investigation of the mass composition of cosmic rays with energies from 3 to 100 EeV
(1 EeV ¼ 10 18 eV) using the distributions of the depth of shower maximum Xmax . The analysis relies on
∼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 Xmax 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 Xmax 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 Xmax 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.},
organization = {Marie Curie Action of the European Union Grant No. 101107047},
organization = {European Union NextGenerationEU,  CN_00000013},
organization = {FEDER Fundação para a Ciência e a Tecnologia (COMPETE)},
organization = {Spain—Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (PID2019–105544 GB-I00, PID2022-140510NB-I00 and RYC2019-027017-I)},
organization = {Xunta de Galicia (CIGUS Network of Research Centers, Consolidación 2021 GRC GI-2033, ED431C-2021/22 and ED431F-2022/15)},
organization = {Junta de Andalucía (SOMM17/6104/UGR and P18-FR-4314)},
organization = {European Union (Marie Sklodowska-Curie 101065027 and ERDF)},
organization = {Marie Curie-IRSES/EPLANET},
organization = {European Particle Physics Latin American Network},
organization = {UNESCO},
publisher = {American Physical Society},
title = {Measurement of the depth of maximum of air-shower profiles with energies between 10 18.5 and 10 20 eV using the surface detector of the Pierre Auger Observatory and deep learning},
doi = {10.1103/PhysRevD.111.022003},
author = {Abdul Halim, A. and Bueno Villar, Antonio and Pierre Auger Collaboration},
}