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