eprintid: 2106
rev_number: 8
eprint_status: archive
userid: 1
dir: disk0/00/00/21/06
datestamp: 2002-05-14 00:00:00
lastmod: 2014-04-03 11:48:56
status_changed: 2012-08-14 15:03:52
type: doctoralThesis
metadata_visibility: show
creators_name: Diaz Trigo, Maria
title: Collecting heat during the day, observing the sky at night : the use of a heliostat field near Almeria to search for cosmic gamma rays
title_de: Sammeln der Hitze waehrend des Tages, beobachten des Himmels waehrend der Nacht : der Gebrauch des heliostat Feldes naehe Almeria zur Suche nach kosmischer Gamma-Strahlung
ispublished: pub
subjects: ddc-530
divisions: i-130001
adv_faculty: af-13
keywords: gamma , ray , astronomy , heliostat , GRAAL
cterms_swd: gamma
cterms_swd: strahlung
cterms_swd: heliostat
cterms_swd: GRAAL
cterms_swd: astronomie
abstract_translated_text: The GRAAL experiment (Gamma Ray Astronomy at ALmeria) is the result of the  conversion of a solar power plant near Almeria into a Cherenkov telescope with  a total mirror area of 2500 m^2 for very high energy gamma astronomy. The  detector is located in a central solar tower and detects photon-induced showers  with an energy threshold of 250 GeV and an effective detection area of about  15000 m^2. The aim of the experiment was the search for very high energy gamma  sources. This thesis describes the installation of the detector and the results of its  operation during more than 2 years. The methods developed for the Monte Carlo  simulation and the analysis of the data are discussed.  A special emphasis is put on the general problems encountered on the  application of this new technique to the observation of gamma-rays common to  all heliostat arrays. In particular, the effect of a field of view restricted  to the central part of a detected air shower on the lateral distribution and  timing properties of Cherenkov light are discussed. Under angular restriction  the differences between gamma and hadron induced showers obliterate, making  an efficient gamma-hadron separation difficult. More than 250 hours of usable data were taken with the GRAAL detector on 18  different sources, among them the Crab nebula, the blazar Markarian 421 and  the gamma-ray burst GRB010222. Evidence for a gamma-ray flux from the direction  of the Crab pulsar and Markarian 421 was found, proving the feasibility of solar  arrays for the observation of gamma-ray sources.
abstract_translated_lang: eng
class_scheme: pacs
date: 2002
date_type: published
id_scheme: DOI
id_number: 10.11588/heidok.00002106
ppn_swb: 1643290576
own_urn: urn:nbn:de:bsz:16-opus-21069
date_accepted: 2002-04-17
advisor: HASH(0x559e353a33a8)
language: eng
bibsort: DIAZTRIGOMCOLLECTING2002
full_text_status: public
citation:   Diaz Trigo, Maria  (2002) Collecting heat during the day, observing the sky at night : the use of a heliostat field near Almeria to search for cosmic gamma rays.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/2106/1/thesis.pdf