Measurement of the depth of maximum of air-shower profiles with energies between 10 [sup] 18.5 and 10 [sup] 20 eV using the surface detector of the Pierre Auger Observatory and deep learning
Abstract
We report an investigation of the mass composition of cosmic rays with energies
from 3 to 100 EeV (1 EeV = 10[sup]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.
Keywords
ultra-high-energy cosmic rays;UHECRs;extensive air showers;Pierre Auger Observatory;UHECR mass composition;depth of shower maximum;fluorescence detector;surface detector;deep learning;
Data
| Language: | English |
|---|---|
| Year of publishing: | 2025 |
| Typology: | 1.01 - Original Scientific Article |
| Organization: | UNG - University of Nova Gorica |
| UDC: | 52 |
| COBISS: |
222998275
|
| ISSN: | 2470-0029 |
| Views: | 114 |
| Downloads: | 0 |
| Average score: | 0 (0 votes) |
| Metadata: |
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Other data
| Pages: | str. 1-30 |
|---|---|
| Volume: | ǂVol. ǂ111 |
| Issue: | ǂissue ǂ2, [article no.] 022003 |
| Chronology: | Feb. 2025 |
| DOI: | 10.1103/PhysRevD.111.022003 |
| ID: | 25738917 |
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