The CANGAROO Experiment

1
The CANGAROO Experiment

• What, Where, Who?
• Air Cherenkov Astronomy
• History
• Telescope Design (in comparison with H.E.S.S.)
• Preliminary Results
• Summary

2
What

• Collaboration of Australia and Nippon for a
  Gamma-Ray Observatory in the Outback
• 2nd generation imaging air cherenkov telescopes

superimposed image
3
Where, Who

• Cherenkov telescope array in Woomera, South
  Australia
• 160m ASL
• 17 institutes from Japan and Australia

4
Air Cherenkov Astronomy

• air shower induced by cosmic gamma
• Cherenkov emission
• optical telescopes for observation
• stereoscopic reconstruction of shower axis

5
CANGAROO I

• 3.8m telescope
• 256 pixels
• in operation since 1992

6
CANGAROO II

• 7m telescope
• since May 1999
• various observations (Crab, Vela, ...)
• focal length 8m
• 512 PMTs
• mirror 30 m2

7
CANGAROO III array

• 4 telescopes
• distance 71m (100m)
• using upgraded C II telescope (in operation)
• 2 telescopes will start in April 2002
• all telescopes 2004

10m (2002)
8
CANGAROO III

• 10m telescopes
• focal length 8m
• 552 PMTs
• mirror 57 m2
• 1st telescope in operation

9
Reflector

• CANGAROO
• 10m parabola
• 57m2
• 114 mirrors 80cm ?
• alignment flood light (5km distance)
• point size 0.2o (FWHM)

• H.E.S.S.
• 13m Davies-Cotton design
• 108m2
• 382 mirrors 60cm ?
• Alignment star light
• point size 0.04o (FWHM)

10
Parabola vs. Davies-Cotton

• ideal mirror parabola ? focal point
• spherical mirror ? focal spot
• Davies-Cotton
• spherical frame
• spherical mirror tiles (same focal length)
• mirror tiles individually aligned
• Parabola made from tiles
• spherical tiles
• different focal length

11
Camera

• CANGAROO
• 552 PMTs
• 0.17o angle
• FoV 4o
• hexagonal shape

• H.E.S.S.
• 960 PMTs
• 0.16o angle
• FoV 5o
• hexagonal shape

12
Trigger

• CANGAROO
• 3 adjacent pixels
• telescope coincidence

• H.E.S.S.
• 3-5 pixels in one sector (lt64 pixel)
• gt 2ns
• 1 sector out of 38 overlapping sectors
• telescope coincidence

13
Data Acquisition

• CANGAROO
• Linux PCs
• camera event 1.5kB
• dead time efficiency 20 _at_ 400Hz

• H.E.S.S.
• Linux PCs
• camera event 1.2 kB
• dead time efficiency 20 _at_ 400Hz

14
CANGAROO and H.E.S.S.
15
Preliminary Results Mkn 421

• strong flare 2001
• large zenith angle 70o
• threshold 10 TeV
• eff. area 8x105 m2
• 80 events/14h gt20TeV

16
Sensitivity
CANGAROO
H.E.S.S.
17
Summary

• Introduction to the CANGAROO experiment
• comparison with H.E.S.S.
• presentation of recent CANGAROO results