Status and Future of the HESS experiment

Status and Future of the HESS experiment Martin Tluczykont for the HESS Collaboration LLR Ecole Polytechnique Joint Symposium on GeV-TeV Astrophysics in the GLAST Era Stanford, September 2004 HESS Phase 1 Status Performance Operation and Observations HESS Phase 2 Concept Expectations Collaboration with GLAST

HESS 1: Stereoscopic System of 4 Cherenkov Telescopes Namibia, Khomas Highlands (23 S, 15 E) Altitude 1800 m 380 mirrors 12 m relectors (4 107 m2 ) 960 PMT cameras (0.16 ) Fast trigger coincidence Electronics integrated in Cameras 5.3 FoV Energy threshold 100 GeV Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 2/26

HESS I Phase 1 Completed First light telescope 1 : June 2002 Two telescopes : March 2003 Stereoscopy : July 2003 Three telescopes : September 2003 Four telescopes : December 2003 Phase 1 completed and operational! Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 3/26

The Mirror Alignment Data PSF 2.3 off axis MC Individual mirror facets steerable Alignment of facets using stars PSF well within specifications Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 4/26

Simulation, Calibration & Analysis Monte Carlo simulations CORSIKA + sim hessarray KASKADE + smash 2 Calibration chains Heidelberg Paris Background subtraction Geometric models Template-model Likelihood-based model Different Calibration methods Laser System Single ph.e. Muon rings Shower reconstruction methods Standard Hillas reconstruction Semi-analytical model 3D-Model Redundance gives confidence: Robust results Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 7/26

HESS 1 Performance: The Crab Nebula (preliminary) HESS: Crab Nebula Preliminary High zenith angle (E thr 325 GeV) Independent analyses give consistent results Spectral index: α = 2.59 ± 0.04 Compatible with previous results Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 8/26

HESS 1 Performance: Sensitivity 0.01 Crab in 25 h 0.05 Crab in 1 h Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 9/26

HESS 1 Performance: Angular resolution Standard analysis: Angular resolution < 0.10 300 250 HESS Preliminary Crab Nebula 2 χ / ndf 216 / 23 p0 324.9 ± 23.59 p1 0.06771 ± 0.001988 200 events 150 100 50 0 0 0.05 0.1 0.15 0.2 0.25 2 2 squared angular distance θ [deg ] Improving with more sophisticated models (Semi-Analytical model & 3D-Model) Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 10/26

HESS 1 Performance: Extended objects / Images Skymaps of Field of View HESS: 1 st ever VHE image 5 deg Field of View Independent Background estimations: Ring-background Template-model Likelihood-based Angular resolution < 0.1 Pointing error 20 Optimum conditions for extended sources and surveys Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 11/26

HESS 1 Performance: Energy Reconstruction MC Energy resolution: 10-20 % Reconstruction bias < 10 % Crab Nebula Spectrum α = 2.59 ± 0.04 stat Whipple: α = 2.49 ± 0.07 HEGRA: α = 2.62 ± 0.05 CAT: α = 2.76 ± 0.04 Flux (E>1 TeV): 2.16 ± 0.08 10 7 m 2 s 1 Whipple: 2.15 ± 0.43 10 7 m 2 s 1 HEGRA: 1.75 ± 0.37 10 7 m 2 s 1 CAT: 1.78 ± 0.39 10 7 m 2 s 1 Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 12/26

HESS Observations Object Significance Flux [σ] [Crab] Crab Nebula > 50 1.00 PSR B1259-63/SS2823 >10 0.05 HESS J1303-63 18 0.10 RXJ 1713.7-3946 20 0.66 Galactic Center 9 0.05 Mrk 421 >50 0.5-5 PKS 2155-304 45 0.10-0.60 1 st source of new HESS catalogue!! Most efficient shift so far : 90 % η 70% Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 13/26

The Future: HESS Phase 2 Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 14/26

HESS Phase 2 = HESS 1 + Very Large Telescope HESS Phase II : additional very large central telescope Event Classes : 1. Mono : VLCT 2. Stereo : VLCT+ LCT or LCT+ LCT HESS I (4 x LCT) Very Large Cherenkov Telescope Very Large Cherenkov Telescope: Reflector : 28 m ( 600 m 2 ) Focal distance 35 m Camera: diam. 2.5 m ( 2000 kg) 2048 PMTs (0.07 /pixel) FoV : 3.5 Trigger rate 2.5-20 khz Faster memories needed ( 500 khz) Minimize data flow: 2 nd level trigger Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 15/26

HESS Phase 2 in Namibia Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 17/26

HESS Phase 2 : Expectations Energy threshold Sensitivity: Stereoscopic mode New HESS event class: E 10-50 GeV Increase sensitivity for E 50-100 GeV Improve resolution for E > 100 GeV Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 18/26

HESS: Summary HESS Phase I completed and fully operational Planned performance achieved (E thr = 100 GeV, Sensitivity 0.05 Crab in 1 h) Outstanding new results Potential for more HESS Phase II is being planned: Objective: close the gap to GLAST Method: additional Very Large Central Telescope Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 19/26

Connecting HESS with GLAST

Future collaboration with GLAST Overlapping energy regime : Observations of the same particle population GLAST trigger for HESS-observations HESS will produce sensitive variability studies Simultaneous observations of a steady source Intercalibration Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 21/26

Future collaboration with GLAST : Intercalibration Flux Intercalibration in the GeV regime HESS II : Systematics GLAST : Systematics schematical, steady state source GLAST : Statistics < 50 GeV approx. 300 GeV HESS II : Statistics MeV GeV TeV Energy Simultaneous observations of steady source estimation of the systematic error of HESS estimation of the statistical error of GLAST Work underway (Pol d Avezac & Martin Tluczykont) Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 22/26

Backup Transparencies Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 23/26

Stereoscopic Observation Technique Hofmann algorithm nr. 3 events 3000 2500 2000 1500 Crab Nebula signal region (N on ) background region (N off ) tracking direction θ reconstructed shower direction 1000 CT System 500 0 0 0.02 0.04 0.06 0.08 0.1 2 2 squared angular distance θ, [deg ] 2 images superposition:... in the camera direction (θ)... at observation level core impact position Hadron rejection: core + amplitude + zenith angle mean scaled width (mscw) frequency 700 600 500 400 300 200 100 0 Crab Nebula θ 2 <0.05 deg 2 photons 36.17 / 11 Constant 634.9 17.63 Mean 0.9987 0.2422E-02 Sigma 0.9499E-01 0.2023E-02 signal region (photons + hadrons) background region (hadronen) signal - background = photonen Gauß fit to photons hadrons 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 mscw Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 24/26

What kind of objects to observe for inter calibration? Steady state source: simplifies a lot Hadronic Naive: straight power law More efficient acceleration at GeV energies? Leptonic? 2 1 1 dn/de, [photons cm s MeV ] 10 7 10 8 10 9 10 10 10 11 10 12 10 13 10 14 10 15 10 16 10 17 10 18 10 19 10 20 10 21 10 22 EGRET data 3EG J2033+4113 GLAST? HEGRA data TeV J2035+415 HESS? 10 2 10 3 10 4 10 5 10 6 10 7 energy, [MeV] ], arb. units -1 TeV -1-2 m flux [ph. s 1 10-1 10-2 energy spectrum index: Γ = 2.2 R± 0.2 stat (H.E.S.S., preliminary) Possible Candidate: HESS 1303-63 Power law: α = 2.2 Flux: 0.1 Crab (E>1 TeV) 10-3 GLAST-detection: O(days) 2 4 6 8 10 12 energy [TeV] Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 25/26

Calibration LED system: Single photo electron spectrum Determination of conversion factors Laser Flatfielding: relative PMT amplitudes Single ph.-electron: conversion factor (gain) Muon Calibration: verification Entries 2 450 χ /dof 1.060 Norm 50314 P 27.31±0.26 400 σ P 16.10 ±0.19 γ e 80.78 ±0.80 350 σ γe 0.46 ±0.01 µ 1.11 ±0.01 300 250 200 150 100 50 Pedestal Single photo electron peak 0 100 50 0 50 100 150 200 250 300 ADC counts (arbitrary offsets) Muon Ring Calibration 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 Data Simulation Corrected Simulation 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 N. Leroy, 2004 collection efficiency Martin Tluczykont for the HESS Collaboration Martin.Tluczykont@poly.in2p3.fr 26/26