Vintage Gamma Rays
Explanation:
Gamma-rays are the most energetic form of
electromagnetic
radiation.
But these high energy photons penetrate and interact in normal materials
and cannot be focused by lenses and
mirrors like those in optical telescopes.
So how do you make an image in
gamma-ray light?
One way is to use a patterned mask of material which can
cast gamma-ray
shadows
on a digital detector array.
The mask is called a
coded
aperture and the resulting shadow patterns can be used to
construct a gamma-ray image of the source.
For example, consider
the picture above.
In place of a
coded mask,
familiar objects were positioned in front of a detector array
and illuminated with gamma-rays in a laboratory test.
Do you recognize
the shadow image?
(Click on the picture for the focused visible light image.)
Destined to fly on the
International Gamma-Ray Astrophysics Laboratory
(
INTEGRAL) satellite
scheduled for launch in October of this year,
the detector array is part of the imaging
gamma-ray telescope,
IBIS.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
