1. CTA Why ?

2. Where do we aim ?

3. The Cherenkov Telescope Array facility • aims to explore the sky in the 10 GeV to 100 TeV energy range • builds on demonstrated technologies • combines guaranteed science with significant discovery potential • is a cornerstone towards a multi-messenger exploration of the nonthermal universe

4. Possible CTA sensitivity GLAST Crab E.F(>E) [TeV/cm2s] 10% Crab MAGIC AGN and pulsar physics H.E.S.S. Exploring the cutoff regime in Galactic sources 1% Crab A deep look at the TeV sky

5. 4 x 4 degr. field SNR models using DAV 94 n = 1 e = 0.1 (consistent with HESS plane scan) assuming 1 mCrab sensitivity

6. How will we do it?

7. Sensitivity Threshold limit from event count, ~ 1/T.A Minimal detectable flux per band Dlog10E=0.2, relative to a power-law Crab spectrum limit from proton bg, ~ 1/q (h.T.A)1/2 limit from syst. error on background, indep. of T,A; ~1/q2 limit from electron bg, ~ 1/q (T.A)1/2

8. Ideal energy-dependent resolution & rejection

9. Ideal energy-dependent resolution & rejection

10. x 1.5 ~3000 m2 mirror area ~4000 m2 mirror area ~5000 m2 mirror area Possible CTA sensitivity GLAST Crab E.F(>E) [TeV/cm2s] 10% Crab MAGIC few 104 m2 with dense coverage (5-10%) H.E.S.S. O(107 m2) with low coverage (0.03-0.05%) 1% Crab few 105 m2 with medium coverage (1-2%)

11. Option: Mix of telescope types Not to scale !

12. CTA as an observatory • CTA will be a normal astrophysical observatory, open to the community, with professional operators, AOs, support for data analysis etc. • Data will be public after some time (1 y?) • Significant guaranteed time (~50%) for construction consortium CTA will most likely combine HEP and astrophysics worlds • Observatory operation • Significant contribution to construction by institute shops to reduce required investment

13. Getting on (the European) track

15. Baseline given in ESFRI LoI

17. The EC/ESFRI route CAPACITIES Work programme – New research infrastructures • Design studies (29 M€) • Construction - Preparatory phase (63 M€) • Infrastructure construction

18. Research Infrastructures in FP7 Robert-Jan Smits DG Research European Commission

19. FP7 Research Infrastructures in brief Existing Infrastructures New Infrastructures Design studies Integrating activities ESFRIRoadmap Construction (preparatory phase; construction phase) e-infrastructures Policy Development and Programme Implementation

20. Planning of calls and indicative budget

21. World wide context CTA as European Initiative • Close cooperation with Japan & US very desirable • Joint technology development or • Joint project • could help to fund 2nd site • Near future: concentrate on FP7 / EC aspects

22. Possible Schedule FP 7 Design Study Prep. Phase ? GLAST “Letter of Intent” (100 pages, physics + conceptual design) Proposal Design Report Products of Design Study

23. Stages • Letter of Intent (spring 07) • Establishs physics case • Discusses basic performance needs • Lists possible sites and key characteristics • Gives examples for array configurations • Gives options for technical implementation • Lists areas where further design is needed • Proposal (summer/fall 08) • Re-iterates physics case • Gives detailed performances for (few) array layouts • Gives details for (few) implementation options • More on site options, organization options • Gives cost estimates • Design report (fall 09) • Final Array layout • Telescope implementation choices and details • List of final few candidates sites {not clear if final site choice} • Proposal for organization, governance, operation

24. What should we have after design study • Detailed knowledge of characteristics, availability of (few) good site candidates • Array layout which optimizes physics performance for a given cost (and which is about 1 order of magnitude better than what we have now) • Detailed design and (industrial) cost estimates for telescopes and associated equipment • Plan how to organize, produce, install, commission, operate the facility; estimate for operating cost • Model and prototype how to handle and analyze the data • Small prototype series of components such as mirrors (~100), photosensors and electronics (~100-200 channels), probably a few drive systems, possible a secondary mirror, … to ensure that production issues and costs are understood

25. Design study structures in Work Packages

26. The challenge- putting the puzzle together

27. Grand Challenge I • Find (and agree on) an array layout that has the required performance

28. Camera field of view Effective field of view for given camera diameter 3o 5o 8o 5o: Easy 7o: Probably doable 10o: Brick wall Best for Galaxy: 7o-9o Best for AGN: small fov • Large homogeneous fov • minimizes systematics • improves high-energy coverage

29. Quantity versus quality (versus R&D time) V. Vassiliev et al., astro-ph/0612718 40000 Pixels in camera for 10o fov

30. x 1.5 ~3000 m2 mirror area ~4000 m2 mirror area ~5000 m2 mirror area Grand Challenge II: Cost and Funding GLAST Crab E.F(>E) [TeV/cm2s] 10% Crab MAGIC few 104 m2 with dense coverage (5-10%) H.E.S.S. O(107 m2) with low coverage (0.03-0.05%) 1% Crab few 105 m2 with medium coverage (1-2%)

31. 2000 1500 2 1000 Cost per 100 m 500 0 0 200 400 600 800 1.000 1.200 2 Mirror area (m ) Grand Challenge II: Cost and Funding 12000 m2 x 1.2 M€/100 m2 = 144 M€ x 1.5

32. Grand Challenge II: Cost and III: Reliability • Reduce cost per area • Can spent a lot on design, if savings in production cost result • Exploit mass production to reduce cost • Reliability • Current telescopes (e.g. H.E.S.S.) have not reached the reliability required for such a large system • Telescope (drives, end switches, …) • Camera • Software & control • Design needs to be optimized for high reliability • To limit operating and maintenance costs • To maximize uptime • To mimimize systematic errors

33. Grand Challenge IV: Coordination Physics Array Site area, height telescope types, size, fov telescope cost trigger options environmental conditions Telescope Optical layout and mirror facets Photon detectors weight fov Electronics Structure Camera Mount & dish

34. Grand Challenge V: Production CTA An advanced facility for ground-based high-energy gamma ray astronomy

35. Grand Challenge VI: Organization • Legal form of the CTA observatory • New (European?) entity ? • Part of existing (European?) organization ? • CERN • ESO • … • Operated by existing national organization ? • DESY • Saclay • Rutherford • other National Labs • Site decision will be influenced by • Choice of host organization • Contribution by host country or (transnational) host region

36. What if … we don’t get the design study? • continue CTA design • little change in work programme, but missing funds will slow things down • apply 2010 for Construction – Preparatory Phase we cannot reach the performance goals within reasonable costs? we cannot agree on a layout & technology? • …