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By Wylie Ballinger and Sam Russell What are Gamma Rays?
What The most potent particles
on the electromagnetic
scale and the known
where an optical photon
has an energy of a few
http://imagine.gsfc.nasa.gov/docs/science/how_l2/gamma_detectors.html Smallest wavelength
Only created by
radioactive atoms and
The hottest regions of the
universe produce them.
Formed by Supernovae,
Pulsars, Neutron Stars,
Black holes, and Gamma
Ray ‘electron volt
The change of potential energy experienced by an electron moving
from a place where the potential has a value of V to a place where it
has a value of (V+1 volt). This is a convenient energy unit when
dealing with the motions of electrons and ions in electric fields; the
unit is also the one used to describe the energy of X-rays and gamma
rays. A keV (or kiloelectron volt) is equal to 1000 electron volts. An
MeV is equal to one million electron volts. A GeV is equal to one
billion (109) electron volts. A TeV is equal to a million million (1012)
http://imagine.gsfc.nasa.gov/docs/science/how_l2/gamma_detectors.html Seeing in Gamma
Seeing Explorer XI launched first satellite in 1961
Explorer was the first gamma ray receiver.
It picked up fewer than 100 cosmic gammaray photons total.
The moon gives off more Gamma Rays
than the sun.
Mirrors don’t work How Do We See Gamma?
How 1-30 MeV Is the ideal range that we wish to
see. Active galaxies, pulsars, and solar flares.
Compton Scattering and how it works.
Compton How Do We See in Gamma? Continued…
I’m a visual person… http://learntech.uwe.ac.uk/radiography/RScience/interactions/comptonscatter.htm So How Does That Work
Again? Crystal Scintillators
Crystal Crystals that emit low energy light (usually visible) when hit by high energy light
such as gamma radiation.
Pair The physical process whereby a gamma-ray photon, usually through an
interaction with the electromagnetic field of a nucleus, produces an electron and
an anti-electron (positron). The original photon no longer exists, its energy
having gone to the two resulting particles. The inverse process, pair annihilation,
creates two gamma-ray photons from the mutual destruction of an
CGRO uses compton scattering and pair production.
CGRO Launched in April 5th, 1991 on Atlantis shuttle. Had a visual range of 30 KeV to
30 Burst And Transient Source Experiment (BATSE), the Oriented Scintillation
Spectrometer Experiment (OSSE), the Imaging Compton Telescope
(COMPTEL), and the Energetic Gamma Ray Experiment Telescope ( EGRET).
http:// Returned to Earth on June 4th 2000.
Gamma-ray Large Area Space Telescope is being sent up by Nasa in 2007. Gamma Ray Bursters
Gamma Does what it says on the box. http://imagers.gsfc.nasa.gov/ems/gamma.html The most energetic things in the
The universe that we know of.
More energy in 10 seconds than our
sun can produce in its entire liftime
of 10,000,000,000 years!
GLAST Gamma-Ray Large Area
Space Telescope Large Area
Telescope Funded Jointly by the US,
Japan, France and Sweden
Japan, Accuracy of 30 Arc seconds Launch in 2006 CGRO
CGRO Compton Gamma Ray Observatory Four telescopes on it:
1. BATSE Base and Transient Source Experiment
2. OSSE Oriented Scintilliation Spectrometer Experiment
3. COMPTEL Imaging Compton Telescope
4. EGRET Energetic Gamma Ray Experiment Telescope CGRO EGRET
CGRO The Compton Gamma
The Ray Observatory
Energetic Gamma Ray
Experiment 80° Field of View Launched in 1991 as an
Experimental Re-entered in 2004 Major EGRET Discoveries
Major The finding of a new class of objects--high
energy gamma-ray emitting blazars, or grazars
The emission of high energy gamma-rays from a
gamma ray burst for over an hour, with some
gamma rays having energies over a GeV and two
having energies over 10 GeV.
The observation of an increased fraction of
pulsar electromagnetic radiation going into
gamma rays as the age of the pulsar increases to
a million years
The determination with high certainty that
cosmic rays are galactic
The detailed mapping of the galactic diffuse
radiation and the measurement of the pion bump
in the high energy gamma-ray spectrum
The absence of microsecond bursts and its
implication for certain unification theories
The long trapping time of over ten hours for
energetic solar particles following a flare
A measurement of the diffuse, presumably
extragalactic, high energy gamma ray spectrum
INTERGRAL International Gamma-Ray
Astrophysics European Space Agency
European Demark, France, Germany, Italy,
Spain and Switzerland
Spain + Czech Republic and Poland With help from Russia and US Giant molecular
cloud in the center of
the galaxy that was
discovered Gamma-Ray Burst over 40 Seconds
Gamma-Ray http://www.rssd.esa.int/Integral/integ_images.html A Cool Picture !!!
http://imagine.gsfc.nasa.gov/docs/science/how_l2/compton_scatter.html http://imagine.gsfc.nasa.gov/docs/science/how_l2/gamma_detectors.html http://imagine.gsfc.nasa.gov/docs/science/how_l1/gamma_detectors.html http://www.astro.utu.fi/~cflynn/astroII/l7.html http://learntech.uwe.ac.uk/radiography/RScience/interactions/comptonscatter.h http://imagine.gsfc.nasa.gov/docs/science/how_l2/gamma_scintillators.html ...
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- Fall '11
- Photon, Gamma ray, GAMMA, Energetic Gamma Ray