# ICRC2015

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

## Improving H.E.S.S. cosmic-ray background rejection by means of a new Gamma-Ray Air Shower Parametrisation (GRASP)

Aug 4, 2015, 4:00 PM
1h
Mississippi Foyer (World Forum)

### Mississippi Foyer

#### World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Board: 75
Poster contribution GA-EX

### Speaker

Dr Francois Brun (CEA-Saclay)

### Description

Imaging Atmospheric Cherenkov Telescopes (IACTs), with their high sensitivity and large field-of-views, are ideal instruments to study the universe in VHE $\gamma$-rays. IACTs image Cherenkov light emitted by $\gamma$-rays from induced particle cascades, developing in the atmosphere. The sensitivity of the IACTs depends critically on their capability to reduce the background caused by the much more numerous hadronic air showers, induced from the hadronic component of the cosmic rays. In this work we apply a new image analysis method using an advanced Gamma Ray Air Shower Parametrisation (GRASP) to data from the High Energy Stereoscopic System (H.E.S.S. Phase I). The new method provides additional classifying variables for a decision tree based learning algorithm to differentiate $\gamma$-ray induced air showers from hadronic ones. When combined with a (recently developed) $\gamma$-ray reconstruction method that uses an Image Pixel-wise fit for Atmospheric Cherenkov Telescopes (ImPACT), a significant improvement in sensitivity is observed compared to the H.E.S.S. Standard Analysis.
Collaboration H.E.S.S. 562

### Co-authors

Dr Francois Brun (CEA-Saclay) Dr Robert Parsons (MPIK)

### Presentation materials

There are no materials yet.