# ICRC2015

July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

## ARGO-YBJ measurements on the EAS-footprint stretching as an effect of the geomagnetic field

Aug 1, 2015, 3:30 PM
1h
Amazon Foyer (World Forum)

### Amazon Foyer

#### World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 202
Poster contribution CR-EX

### Speaker

Ivan De Mitri (Univ. of Salento and INFN, Lecce, Italy)

### Description

In a latest paper the ARGO-YBJ experiment proved the effect of the geomagnetic field (GeoMF) on the development of extensive air showers (EAS) and the dependence of the trigger rate ($\lambda$) on the coupling angle ($\xi$) between GeoMF and EAS axis, according to the formula $\lambda$ = $\lambda_0 (1-\eta \ sin^2 \xi)$. The value $\lambda_0$ depends on the EAS zenith angle, while the parameter $\eta$ depends on the position of the EAS core. Indeed $\eta$ is positive (negative) and the trigger rate is reduced (enhanced) for showers with the core inside (outside) the trigger area. In this work the strong dependence of $\eta$ on the core position is studied very deeply and the results make more evident that the charged-particle lateral distribution is stretched by the magnetic forces. This means that the particle density is reduced near the EAS-core and increased on the EAS-tails. Obviously the effect depends on the GeoMF-EAS coupling and is confirmed looking at the lateral distribution as a function of core position and EAS direction.
Registration number following "ICRC2015-I/" 778 ARGO-YBJ

### Primary authors

Dr Antonio Surdo (INFN Lecce, Italy) Dr Giovanni Marsella (Univ. of Salento and INFN, Lecce, Italy) Dr Lorenzo Perrone (Univ. of Salento and INFN, Lecce, Italy) Prof. Paolo Bernardini (Univ. of Salento and INFN, Lecce, Italy)

### Co-author

Ivan De Mitri (Univ. of Salento and INFN, Lecce, Italy)

### Presentation materials

There are no materials yet.