# AugerPrime: the Pierre Auger Observatory Upgrade

## TL;DR

The paper discusses the upgrade of the Pierre Auger Observatory to better understand ultra-high energy cosmic rays, focusing on primary composition, anisotropy, and hadronic interactions at energies beyond current accelerators.

## Contribution

It introduces the AugerPrime upgrade, detailing new detector components and their expected improvements in cosmic ray composition and interaction studies.

## Key findings

- First data collected with the upgraded detectors.
- Enhanced sensitivity to primary mass composition.
- Potential to identify sources of ultra-high energy cosmic rays.

## Abstract

The world largest exposure to ultra-high energy cosmic rays accumulated by the Pierre Auger Observatory led to major advances in our understanding of their properties, but the many unknowns about the nature and distribution of the sources, the primary composition and the underlying hadronic interactions prevent the emergence of a uniquely consistent picture. The new perspectives opened by the current results call for an upgrade of the Observatory, whose main aim is the collection of new information about the primary mass of the highest energy cosmic rays on a shower-by-shower basis. The evaluation of the fraction of light primaries in the region of suppression of the flux will open the window to charged particle astronomy, allowing for composition-selected anisotropy searches. In addition, the properties of multiparticle production will be studied at energies not covered by man-made accelerators and new or unexpected changes of hadronic interactions will be searched for. After a discussion of the motivations for upgrading the Pierre Auger Observatory, a description of the detector upgrade is provided. We then discuss the expected performances and the improved physics sensitivity of the upgraded detectors and present the first data collected with the already running Engineering Array.