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
Minimal detectable flux per band Dlog10E=0.2, relative to a
power-law
Crab spectrum
Threshold
limit from
event count,
~ 1/T.A
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. Possible CTA sensitivity
~3000 m2 mirror area
~5000 m2 mirror area
~4000 m2 mirror area
x 1.5
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 ( %)
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
Integrating activities
Design studies
Construction (preparatory phase; construction phase)
ESFRI Roadmap
e-infrastructures
Policy Development and Programme Implementation

20. Total operational budget 1630 M€
Planning of calls and indicative budget
Total operational budget 1630 M€
Call
Call
Call
Call
Integrating activities
275 x
e-Infrastructures 89
115
Design studies 35
Construction – Support to the Preparatory Phase
135
Construction – Support to the Implementation Phase
RSFF (200 M€) M€
Policy Development and Programme Implementation 25 5
Total per call (M€)
284
395

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 06 07 08 09 10 11 12 13 Site exploration
FP 7 Design Study
Prep. Phase ? 06 07 08 09 10 11 12 13
Site exploration
Array layout
Telescope design
Component prototypes
Array prototype
Array construction
Partial operation
GLAST
“Letter of Intent”
(100 pages, physics
+ conceptual design)
Proposal
Design
Report
Products of
Design Study

23. Stages Letter of Intent (spring 07) Proposal (summer/fall 08)
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 (~ 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
WP1
Management of the design study
WP2
Astrophysics and astroparticle physics
WP3
Optimization of array layout, performance studies and analysis algorithms
WP4
Site selection and site infrastructure
WP5
Telescope optics and mirror
WP6
Telescope structure, drive, control
WP7
Photon detectors and focal plane
WP8
Readout electronics and trigger
WP9
Instrument calibration and analysis algorithms {merge with WP10?}
WP10
Atmospheric monitoring and associated science
WP11
Observatory operation and access (TOC + SOC)
WP12
Data handling, data processing, data management and data access (SDC)
WP13
Risk assessment and quality assurance, production planning (?)
WP14
Resource exploration

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
5o: Easy
7o: Probably doable
10o: Brick wall
Large homogeneous fov
minimizes systematics
improves high-energy coverage
Best for Galaxy: 7o-9o
Best for AGN: small fov

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

30. Grand Challenge II: Cost and Funding
~3000 m2 mirror area
~5000 m2 mirror area
~4000 m2 mirror area
x 1.5
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 ( %)
1% Crab
few 105 m2 with medium coverage (1-2%)

31. Grand Challenge II: Cost and Funding
500
1000
1500
2000
200
400
600
800
1.000
1.200
Cost per 100 m 2
Mirror area (m )
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
Site
Array
Physics
area,
height
telescope types, size, fov
telescope cost
trigger options
environmental
conditions
Telescope
Photon detectors
Optical layout and
mirror facets
weight
fov
Electronics
Structure
Camera
Mount & dish

34. Grand Challenge V: Production
C TA 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? …