Air Cherenkov Telescope Arrays Air Cherenkov Telescope Arrays - - PowerPoint PPT Presentation

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Air Cherenkov Telescope Arrays Air Cherenkov Telescope Arrays - - PowerPoint PPT Presentation

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Air Cherenkov Telescope Arrays Air Cherenkov Telescope Arrays as SII receivers as SII receivers Imaging Air Cherenkov Telescope (IACT) arrays are appealing for Intensity

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SLIDE 1

Stephan LeBohec, University of Utah SIIWG Workshop, SLC, Friday January 30th 2009

Air Cherenkov Telescope Arrays Air Cherenkov Telescope Arrays

  • as SII receivers

as SII receivers

Imaging Air Cherenkov Telescope (IACT) arrays are appealing for Intensity Interferometry because of the large number of simultaneous baselines between large light collectors they might offer. I will present the sensitivity possibilities, constraints and limitations associated with the utilization

  • f

IACT for Stellar Intensity Interferometry.

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SLIDE 2

2006 1963

J.E. Grindlay, 1975 uses the Narrabri telescopes to observe Cen A in gamma TeV energies 2008 we could start using TeV gamma ray telescopes as Intensity Interferometer receivers

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SLIDE 3

NSII:

Two telescopes

  • n circular tracks

* No signal delays * Range of baselines (10m - 200m)

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SLIDE 4

HESS 12m telescope array (Namibia) HESS 12m telescope array (Namibia) VERITAS 12m telescope array (Arizona) VERITAS 12m telescope array (Arizona)

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SLIDE 5

VERITAS as an interferometer

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SLIDE 6

A possible design for CTA A possible design for CTA Cherenkov Telescope Array Cherenkov Telescope Array

100m2 600m2

4656 baselines 47 baseline lengths Construction: 2012

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SLIDE 7

CHARA CHARA

“Imaging the surface of Altair” “Imaging the surface of Altair” J.D. Monnier, et al., 2007, J.D. Monnier, et al., 2007,

  • Science, 317, 342.

Science, 317, 342.

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SLIDE 8

CTA CTA

SII SII imaging imaging capabilities capabilities See Paul Nunez phase See Paul Nunez phase and image reconstruction and image reconstruction

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SLIDE 9

SII receiver convertion

  • f IACTs

(Interferometric observation during full moon) Camera shutter integration

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SLIDE 10

Geometrical optics digression 12m f/1 Davis-Cotton

  • 0.05o PSF = 10mm

10nm OBW = Collimation to ~5o f/1 Collimator ø=10mm/tan(5)=110mm

From f/1 Davis-Cotton 5o collimation 110mm analyzer 110mm collimator 110mm concentrator

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SLIDE 11

Parabolic optics preserves timing

Camera

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SLIDE 12

Davis-Cotton optics used for IACT

in order to minimize PSF degradation toward the edge of the fov

12m Davis-Cotton f/1 = 4ns dispersion

  • ~100MHz signal bandwidth limitation

Camera

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SLIDE 13

Sensitivity? Sensitivity?

A=100m2 α=30% Δf=100MHz T=5 hours S/N=5 For |γ|2=0.5 n ~ 5.5mV & Δr=14% @ 3.7mV , Δr=3% This is with just one baseline!!!

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SLIDE 14

With many baselines... With many baselines...

PSF PSF limitation: limitation: 0.05 0.05o

  • -> 9.6m
  • > 9.6mV

0.01 0.01o -> 13.0m

  • > 13.0mV
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SLIDE 15

So there is an interesting potential . . .

  • Now what?

Implementing SII with IACT arrays Two types of considerations 1) SII specific technology 2)IACT facility interfacing and adaptation

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SLIDE 16

1) SII specific technology

* Optics * Photo-detectors

  • see David Kieda’s presentation

* Signal transmission

  • see Michael Daniel’s presentation

* Correlation

  • see presentations by
  • Erez, Dainis, Giampiero, Stephan,…

IT SEEMS WE’VE GOT EVERY THING ALREADy!

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SLIDE 17

2) IACT facility interfacing adaptation

* Focal plane implementation

  • camera shutter = space and freedom
  • CTA in need of specifications
  • (volume, weight, power, …)

* Parabolic instead of Davis Cotton

  • Not likely to happen (larger f/d & cost)
  • from 100MHz to 1GHz SN x √10 = 1.2mv
  • 1GHz implies 100ps timing
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SLIDE 18

2) IACT facility interfacing adaptation

  • * Should redundancy be reduced?
  • % Analysis (higher order or not)

% Science (low order imaging or imaging)? SKA NORTH SOUTH

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SLIDE 19

2) IACT facility interfacing adaptation

* Add a couple of telescopes

  • for shorter baselines?
  • Should they be smaller so as to
  • not resolve bright stars?

Aliasing

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SLIDE 20

2) IACT facility interfacing adaptation

* Real estate issues

  • Conduits
  • Building (correlator location,
  • control room, … )
  • Observation programming
  • Observing modes
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SLIDE 21

Conclusions

* SII with IACT: real science potential

  • Bright moon time
  • IACT science output increased
  • Synergy Optical % High Energy

* Technology already available

  • Choices to be made
  • Several ongoing prototyping

* CTA is going to happen

  • Construction starting 2012
  • Now is the time to get involved
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SLIDE 22

Hardware budget:

  • A shot in the dark:

Secondary optics= $5,000 x 97 Photo-detector = $2,000 x 97 Signal transfer = $1,500 x 97 Correlators = $200 x 4656 Computing = $20,000 TOTAL =$1,775,700

  • Say $2M