Related papers: An elastic lidar system for the H.E.S.S. Experimen…
Ground-based atmospheric Cherenkov telescopes are proven to be effective instruments for observations of very high energy (VHE) gamma-radiation from celestial objects. For effective use of such technique one needs detailed Monte Carlo…
The high energy end of gamma-ray source spectra might provide important clues regarding the nature of the processes involved in gamma-ray emission. Several galactic sources with hard emission spectra extending up to more than 30TeV have…
A search for dark matter line-like signals was performed in the vicinity of the Galactic Centre by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis was developed to improve the sensitivity to…
This thesis presents the study of four aspects of high energy astronomy. The first part of the thesis is dedicated to an aspect of instrument development for imaging atmospheric Cherenkov telescopes, namely the Level 2 trigger system of the…
There are currently no experiments, either satellite or ground-based, that are sensitive to astrophysical gamma-rays at energies between 20 and 250 GeV. We are developing the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) to…
The stereoscopic imaging atmospheric Cherenkov technique, developed in the 1980s and 1990s, is now used by a number of existing and planned gamma-ray observatories around the world. It provides the most sensitive view of the very high…
During the last decade, imaging atmospheric Cherenkov telescopes (IACTs) have proven themselves as astronomical detectors in the very-high-energy (VHE; E>0.1 TeV) regime. The IACT technique observes the VHE photons indirectly, using the…
The quasar PKS 1510-089 (z=0.361) was observed with the H.E.S.S. array of imaging atmospheric Cherenkov telescopes during high states in the optical and GeV bands, to search for very high energy (VHE, defined as E >= 0.1 TeV) emission. VHE…
The shell-type supernova remnant RX J0852.0-4622 was observed with the High Energy Stereoscopic System (H.E.S.S.) of Atmospheric Cherenkov Telescopes between December 2004 and May 2005 for a total observation time of 33 hours, above an…
A new background rejection strategy for gamma-ray astrophysics with stereoscopic Imaging Atmospheric Cherenkov Telescopes (IACT), based on Monte Carlo (MC) simulations and real background data from the H.E.S.S. [High Energy Stereoscopic…
The energetic bremsstrahlung photons up to 100 MeV produced in heavy ion collisions can be used as a sensitive probe to the short range correlation in atomic nuclei. The energy of the $\gamma$-rays can be measured by collecting the…
The results of the first extragalactic gamma-ray survey by the High Energy Stereoscopic System (H.E.S.S.) are presented. The survey comprises 2720 hours of very high-energy gamma-ray observations of the extragalactic sky, recorded with…
The High Energy Spectroscopic System (H.E.S.S.) is pursuing a rich observational program in astroparticle physics. The latest results from H.E.S.S. on the search for dark matter towards the Galactic Center and dwarf galaxies, the test of…
We present a sophisticated gamma-ray likelihood reconstruction technique for Imaging Atmospheric Cerenkov Telescopes. The technique is based on the comparison of the raw Cherenkov camera pixel images of a photon induced atmospheric particle…
A deep observation campaign carried out by the High Energy Stereoscopic System (H.E.S.S.) on Centaurus A enabled the discovery of gamma rays from the blazar 1ES 1312-423, two degrees away from the radio galaxy. With a differential flux at 1…
The resolution power of current Imaging Atmospheric Cherenkov Telescopes is presently restricted to scales of a few arcminutes. In the very high-energy (VHE; E > 100 GeV) gamma-ray regime, the measurement of source sizes that are comparable…
Mkn 421 was observed during a high flux state for nine nights in April and May 2004 with the fully operational High Energy Stereoscopic System (H.E.S.S.) in Namibia. The observations were carried out at zenith angles of…
Wide-angle, non-imaging air Cherenkov detectors provide a way to observe cosmic gamma-rays which is complementary to observations by imaging Cherenkov telescopes. Their particular strength lies in the multi-TeV to ultra high energy range (E…
For the current generation of Imaging Atmospheric Cherenkov Telescopes (IACTs), with their large mirrors and their cameras with fine segmentation of photodetectors, the focusing capability is a relevant issue. The optical system of an IACT…
The Imaging Atmospheric Cherenkov technique allows to detect very high energy gamma rays from few tens of GeV to hundreds of TeV using ground-based instrumentation. At these energies a gamma ray generates a shower of secondary particles…