title: GRASP - Development of an event reconstruction method using a  Gamma Ray Air Shower Parameterisation and application to   gamma-ray sources with H.E.S.S.
creator: Hillert, Andreas
subject: ddc-520
subject: 520 Astronomy and allied sciences
subject: ddc-530
subject: 530 Physics
description: The H.E.S.S. experiment, with its high sensitivity and large field-of-view, is an ideal instrument to survey the Milky Way in VHE gamma-rays. An accurate reconstruction of  the gamma-ray direction as well as a strong reduction of the hadronic background is essential for the analysis of the data. In this work a reconstruction algorithm is developed that applies a fit of pixel amplitudes to an expected image obtained from a Gamma Ray Air Shower Parameterisation (GRASP). This parameterisation was obtained using Monte Carlo air shower simulations by parameterising the angular Cherenkov photon  distribution with suitable analytical functions. Furthermore, it provides new classifying  variables to differentiate gamma-ray induced air showers from hadronic ones. The reconstruction of air shower parameters is achieved by a maximum likelihood fit and improves the angular resolution by 20-30% with respect to traditional image moment analysis methods. In combination with a MVA-based background rejection method using these  new classifying variables the sensitivity can be improved by about 70%. An analysis of the Pulsar Wind Nebula MSH 15-5-2 and investigation of its morphology and spectral  properties show an indication of energy dependent morphology in VHE gamma-rays.
date: 2014
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/17199/1/PhD-Thesis-AndreasHillert-Final.pdf
identifier: DOI:10.11588/heidok.00017199
identifier: urn:nbn:de:bsz:16-heidok-171999
identifier:   Hillert, Andreas  (2014) GRASP - Development of an event reconstruction method using a Gamma Ray Air Shower Parameterisation and application to gamma-ray sources with H.E.S.S.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/17199/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng