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Cherenkov Telescope Array: Advanced Facility for Ground-based Gamma-ray Astronomy

The Cherenkov Telescope Array (CTA) is an advanced facility for ground-based gamma-ray astronomy with improved sensitivity and angular resolution. It aims to extend the energy range, increase survey capabilities, and monitor multiple objects simultaneously.

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Cherenkov Telescope Array: Advanced Facility for Ground-based Gamma-ray Astronomy

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  1. The Cherenkov Telescope Arrayan advanced facility for ground-based gamma ray astronomy Jean-Francois Glicenstein IRFU, CEA-Saclay Cherenkov Telescope Array J-F Glicenstein

  2. Status of VHE gamma-ray astronomy The VHE gamma-ray sky (March 2010) http://www.mppmu.mpg.de/~rwagner/sources/ ~100 sources (60 galactic) Cherenkov Telescope Array J-F Glicenstein

  3. Physics and « wish list » • extend E range beyond 50 TeV • better angular resolution • larger FOV • Galactic sources • AGN • Surveys • New physics • clusters/extended sources • dark matter and astroparticle physics • monitor many objects simult. • extend E range under 50 GeV • increase surveying capabilities • better flux sensitivity (factor > 10)

  4. The CTA concept 2 arrays: north+south  all-sky coverage core array 100 GeV-10 TeV ~ 40 ø=12 m telescopes low energy section Ethresh ~ 10 GeV a few ø=23 m telescopes high energy section ~ 40 ø=6 m tel. on 10 km2 area Cherenkov Telescope Array J-F Glicenstein

  5. Performances: array sensitivity x 10 flux sensitivity gain energy range increase K. Bernloehr, arXiV0801.5722 Cherenkov Telescope Array J-F Glicenstein

  6. Performances: angular resolution • Angular resolution improves as more telescopes used in reconstrution • Angular resolution closer to theoretical limit MILAGRO HAWC Fermi HESS factor 3 improvement CTA theoretical limit (Hoffman 2005) S.Funk, J.A. Hinton, arXiV0901.2153

  7. CTA operation modes Survey mode: Full sky at current sensitivity in ~1 year Monitoring 4 telescopes Very deep field Deep field ~1/3 of telescopes Cherenkov Telescope Array J-F Glicenstein

  8. Expectations for Galactic plane survey Funk,Hinton,Hermann,Digel, arXiV0901.1885 • assumes • x 2 improvement in hadron rejection • x 2 gain in angular resolution • x 10 gain in effective area  overall increase in sensitivity of ~ 9 • expect ~ 300 sources in -30 deg≤ l ≤ 30 deg. HESS map of the Gal.plane, total exp ~500 hours simulated CTA map, flat exposure ~ 5 hours/field Cherenkov Telescope Array J-F Glicenstein

  9. Fundamental physics: Dark Matter Draco dwarf galaxy, 20 hours Ursa Minor dwarf galaxy • flux sensitivity better by one order of magnitude • better angular resolution  enhanced S/N for NFW profiles • sensitive to DM annihilations from Draco,Sculptor, Sgr dwarf • other target:clumps from the galactic halo 95% CL exclusion region Astrophysical uncertainties Annihilation cross section for thermally-produced DM 330 GeV c J.Buckley et al, arXiV0810:0444 E. Moulin, A. Viana Cherenkov Telescope Array J-F Glicenstein

  10. The CTA design study • Aims: • select the appropriate sites • reduce production costs of telescopes, sensors, electronics etc (technology already proven with HESS, MAGIC,VERITAS). • improve reliability of components and systems • 22 countries (France, Germany, Spain, Poland, Italy ..) • ~ 180 FTE physicists+engineers • spokespersons: W.Hoffman (MPIK Heidelberg) M.Martinez (IFAE, Barcelone) • competiting project: AGIS (USA), merge likely at some point • design study started in 2008 (Barcelona meeting) • new organization for the CTA-PP (preparatory phase of the FP7, to start in 2010) Cherenkov Telescope Array J-F Glicenstein

  11. Workpackages of the DS performances physics cases instruments observatory selection and operations Cherenkov Telescope Array J-F Glicenstein

  12. Site Evaluation • Goal: short list of sites (Northern, Southern hemisphere) • Contact with other projects(AGIS,LLAMA) • Requirements: • Flat Area 3km x 3km (South), 1km x 1km(North) • Cloud Coverage: > 70% of clear nights • Altitude 1500m –4000m • Latitude +30N -30S • dry, transparent, low aerosol atmosphere • Infrastructures • Roads • Hospitals • Airports White: 6 criterias Ligth red: 5 Dark red: 4 Orange: 3 Green: 2 Dark green: 1 Map obtained with FriOwl C.Medina, CBoisson Cherenkov Telescope Array J-F Glicenstein

  13. Site evaluation (2) • Precise measurements to follow on the short list of sites. • Site visit to evaluate infrastructure potential • Atmosphere measurements: LIDAR, seeing.. • Potential sites in Argentina, Namibia, South Africa (South) Canaries, Baja California (North) 30 cm telescope (« miniscope ») seeing monitor Warsaw University PMT (UVScope) +8x8 MAPMT camera NSB measurements transparency INAF/ISAF Palermo Cherenkov Telescope Array J-F Glicenstein

  14. CTA instruments mirrors focal plane telescope electronics focal plane instruments Cherenkov Telescope Array J-F Glicenstein

  15. Requirements for telescopes • dish ø=6 m (small) ø=12 m (medium) ø=23 m (large) • dish shape spherical (Davies-Cotton): S+M, parabolic (L) • f/d = 1.4 (M) and 1.2-1.4 (L) • Camera Field of View: 8° (M), 5° (L) • Number of pixels in camera ~ 1500 (M), ~2500 (L) • Camera weight: 2.5 tons (M), 2 tons (L) P.Colin Cherenkov Telescope Array J-F Glicenstein

  16. Small size telescope • 2 options: • (baseline) 6 meter dish, camera 9 deg FOV, 1300 PMT • 2 mirror design, primary mirror 3.5 m, camera 8 deg FOV, 1600 pixels MAPMT or SiPM INAF UK groups MPIK Heidelberg IFJ Pan Cherenkov Telescope Array J-F Glicenstein

  17. 12-meter class telescopes • previous designs: HESS, VERITAS OK • CTA DS focused on • cost reduction, • improvement of reliability .. HESS VERITAS Cherenkov Telescope Array J-F Glicenstein

  18. 12-meter class telescopes (2) • DESY (Zeuthen, Hamburg), ANL, IRFU Saclay design • Prototype to be built in Berlin in 2010-2011 Cherenkov Telescope Array J-F Glicenstein

  19. 23-meter class telescopes • possible design: extrapolate from MAGIC 17 m telescopes MAGIC MERO (company) design MPI-P Munich, LAPP Annecy Cherenkov Telescope Array J-F Glicenstein

  20. CTA instruments mirrors Cherenkov Telescope Array J-F Glicenstein

  21. Mirror specifications • hexagonal • size: 1200 mm ± 2 mm flat to flat (MST prototype) • weight < 35 kg/m2 (including AMC and fixations) • reflectance > 80% (300-600 nm) • spot size < 1mrad (68% containment) • spherical with radius 30-40 m (MST), aspherical (LST) Cherenkov Telescope Array J-F Glicenstein

  22. Mirror developpement (1) • MAGIC I-II aluminium mirror (INFN Padova) • diamond milling • MAGIC II glass mirrors (INAF, Mediolario) • produced by the « cold slumping » technique. Cherenkov Telescope Array J-F Glicenstein

  23. Mirror developpement (2) • Carbon/glass fiber composite mirrors (IRFU-Saclay, IFJ Cracow, SRC Warsaw) Mold with suction Carbon sheets 1.5 mm thick Cherenkov Telescope Array J-F Glicenstein

  24. Mirror R&D at IRFU-Saclay Carbon fiber Glass fiber Aluminium Cherenkov Telescope Array J-F Glicenstein 24

  25. CTA instruments focal plane instruments Cherenkov Telescope Array J-F Glicenstein

  26. Focal plane instrumentation (1) • Baseline option: PMTs (Hamamatsu, Electron Tubes) • look for compromise between QE, afterpulsing, pulse width, cost.. selection box for HESS2 R8619 R9420-100 Quantum efficiencies M.Shayduk et al, NIM A (2010) Afterpulsing rates J.Bolmont Cherenkov Telescope Array J-F Glicenstein

  27. Focal plane instrumentation (2) G-APD+ MAGIC read-out • other options: MCPPMT,G-APD • useful for 2-mirror telescopes designs • test: 4 MPPC in MAGIC camera A.Biland et al, NIM A (2008) • FACT camera (see talk by T.Krahenbuhl) I.Braun et al, NIM A (2009) • full camera • 1440 pixels • on HEGRA CT3 telescope 1 pixel=4 G-APD Winston cone Hamamatsu MPPC S10362-33-50C 50 m x 50 m cell size Weitzel et al, ICRC 2009

  28. CTA instruments electronics Cherenkov Telescope Array J-F Glicenstein

  29. Signal readout and telescope trigger • Options for camera: • compact camera with electronics on board (HESS, VERITAS) or • signal sent to ground (MAGIC) • compact option was retained (except maybe LST…) • Options for read-out: • Sampling at ~ 300 MHz with FADC (fully digital camera) MPIK Heidelberg, ETH Zurich, Leeds, Uni. Zurich, AGH • analogue memories (1 GHz sampling)+ADC Pisa, IRFU Saclay, LPNHE, LPTA, Uni. Barcelona • Local trigger of telescope: • analog or digital (analogue memories based read-out) spanish groups (IFAE..), DESY • digital (FADC) Cherenkov Telescope Array J-F Glicenstein

  30. Analogue memories-based FE boards • NECTAr: IRFU/LPNHE/LPTA/Univ. Barcelona • see poster by S.Vorobiov • based on SAM chip (HESS2) • new developpment to reduce power consumption and integrate the ADC • Dragon: Pisa • based on commercially available DRS-4 chip photons digital output to acq. farm integrated analogue memories+ ADC conversion NECTAr Cherenkov Telescope Array J-F Glicenstein

  31. Tests of FE boards NECTAr: test board for Gbit ethernet transmission DragonI test board Cherenkov Telescope Array J-F Glicenstein

  32. Array trigger MPIK Heidelberg/ APC Paris • Idea: keep all locally triggered event in a deep (1 s) FIFO • Trigger decision done centrally on time coincidences • Require clock synchronisation with a few ns accuracy MUTIN board (APC) Cherenkov Telescope Array J-F Glicenstein

  33. Timeline for CTA design study fp7 prep. phase conceptual design report Cherenkov Telescope Array J-F Glicenstein

  34. Summary and prospects • CTA will be the major observatory in VHE gamma ray astronomy in the 2020s with both guaranteed astrophysics and a significant discovery potential. • The CTA design study is aiming at reducing costs and improving reliability of instruments and systems. • It is still on-going, with significant advances in mirror technology, telescope design (MST), electronics. • The FP7 prep. phase for CTA should start in 2010 (duration 3 years). Cherenkov Telescope Array J-F Glicenstein

  35. BACK-UP SLIDES Cherenkov Telescope Array J-F Glicenstein

  36. Front end electronics - Krakow CTA meeting

  37. Dragon-I Prototype • Prototype board – Dragon-I • Design driven by mechanical constraints to match Magic-II cluster box • Small form factor FPGA • Altera Cyclone • Fitted in PMT cluster box • Dimensions 5x20 cm • 8 input channels • 7 from PMTs • 1 free (e.g. ext clock) • Octal ADC • AD9222 run at 32 MHz • Parallel LVDS read-out • Dual readout interface • USB2.0 • Bitwise QuickUSB module • Ethernet 100Mbps • Matches the 5 MB/s transfer goal TRG IN CLK IN Cyclone FPGA ADC DRS4 QuickUSB module Ethernet 5 cm 20 cm Dragon-I – USB2.0 and Ethernet versions Dragon sampler CTA ELEC/FPI WP Meeting Tuesday April 7 2009, Paris

  38. From the ARS0 to the NECTAr analog memory HESS1 HESS2 CTA (proposed) (*) New measurements

  39. NECTar analog memories: wide layout option NECTAR CORE SAM CORE • 4*1024 cell matrix • DAC removed • integration of the ADCs Swift Analog Memories 11 mm2, 60000 transistors

  40. Procédé (1) • bandes de G10, aluminium • ou carbone préformées • épaisseur 1.5 mm • rayon de courbure d’un des côtés: • ~ 30 mètres • collage en forme de treillis Cherenkov Telescope Array J-F Glicenstein

  41. Procédé (2) • collage des panneaux carbone • sur le treillis au dessus du moule • collage de la feuille de verre • au dessus du moule • aluminisation moule 50x50 + dispositif de suction Mold with suction Carbon sheets 1.5 mm thick Cherenkov Telescope Array J-F Glicenstein

  42. HESS Old foam mirror Saclay -carbon Cherenkov Telescope Array J-F Glicenstein

  43. CTA in context of HE/VHE gamma rays facilities Cherenkov Telescope Array J-F Glicenstein

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