# Study of Risetime as a function of the distance to the Shower Core in the Surface Detector (SD) of the Pierre Auger Observatory

## TL;DR

This paper investigates how the risetime of air shower signals varies with distance from the core in the Pierre Auger Observatory, aiming to improve understanding of cosmic ray composition.

## Contribution

It introduces a new variable related to risetime as a function of core distance, enhancing mass composition analysis of cosmic rays.

## Key findings

- Risetime varies with distance and zenith angle.
- A new risetime-based variable is proposed.
- Potential for improved cosmic ray composition analysis.

## Abstract

Cosmic Rays (CR) are high energy particles which come from the universe. When one of those particles enters to the atmosphere of the earth it produces an air shower, conformed by secondary particles in which the initial energy is distributed. The Pierre Auger Observatory, located in Argentina, is dedicated to the study of those events. One of the main goals is to find out where those CR are coming from and which kind of chemical composition do they have. In this work we show the status of a study of the risetime as a function of the distance to the shower core (near to the air axis of the shower) for different zenith angles and energies, obtaining a new variable that will be compared with other variables used by the Observatory. The main objective of this study is to better understand risetime as a mass composition sensitive parameter of CR.