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Status of the H.E.S.S. Experiment and First Results
Paula Chadwick
University of Durham, U.K.
for the H.E.S.S. Collaboration
Ground-based -ray TelescopesDetect gamma rays via the Cherenkov light produced by secondary showers – most usually in the atmosphere.
Imaging atmospheric Cherenkov telescopes have:
• Large effective area
• Excellent background rejection
• Good source location
The H.E.S.S. CollaborationMPIK, Heidelberg
Humboldt Universität, Berlin
Ruhr- Universität, Bochum
Universität Hamburg
Landessternwarte Heidelberg
Universität Kiel
Ecole Polytechnique, Palaiseau
LPHNE, Universités Paris VI-VII
PCC Collège de France, Paris
Université de Grenoble
CERS Toulouse
CEA Saclay
Observatoire de Paris-Meudon
University of Durham
Dublin Institute for Advanced Studies
Charles University, Prague
Yerevan Physics Institute
University of Namibia
University of Potchefstroom
H.E.S.S. Location
H E S S s iteH.E.S.S
Vital Statistics
• 4 telescopes in Phase 1• Arranged on a square
of side 120m• Diameter 12m, area
108 m2
• 382 mirrors• Focal length 15m• 960-pixel camera• Total telescope weight
around 60 tonnes
Measured spot width 0.02º for angles between 0 and 45º.
MirrorsQuartz-coated aluminized glass, reflectivity > 80%
The Cameras960 photon detector elements, each subtending 0.16o angle, using 29 mm, Photonis 8-stage PMTs with borosilicate windows, equipped with Winston cones to improve light collection.
The final result weighs about 800 kg, is 1.6 m in diameter and 1.5 m in length. Close to 5kW of heat is dissipated by 80 computer-controlled fans.
Telescope monitoringTelescope pointing is monitored by CCDs
LEDs in the camera lid simulate events
A laser/LED system flat-fields the camera
Information from the CCD cameras allows the pointing to be corrected to give a resolution of 2.5 arcsec.
Calculations courtesy of Stefan Gillessen
Atmospheric MonitoringComprehensive monitoring with IR detectors on each telescope, scanning IR detector, LIDAR and of course a weather station on site.
The ROTSE 3C
First light June 18 2003. Designed for GRB location; some time available to H.E.S.S.
Telescope no. 3 has all mirrors installed and aligned
The 1st 2 telescopes are fully operational
First Results: The Crab Nebula4.65 hours of on-source observations, z.a. range 45-50º, one telescope only.
20.1σ, 3.6 gammas/min
See Masterson’s paper at the ICRC
First Results: PKS2155-304
July 2002: 2.2 hours, 9.9σ, 3.1 gammas/min
Oct 2002: 4.7 hours, 6.6σ, 1.2 gammas/min
See Djannati-Ataï’s paper at the ICRC.
To Conclude….
• The first two H.E.S.S. telescopes are fully operational
• The third telescope has mirrors fitted and aligned
• Phase 1 completion early 2004
• The Crab Nebula and PKS2155-304 have been detected with the 1st telescope alone
• Routine observations are under way