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Unformatted text preview: 100’s of free ppt’s from 100’s www.pptpoint.com library www.pptpoint.com Project Gamma Project By Wylie Ballinger and Sam Russell What are Gamma Rays? What The most potent particles The on the electromagnetic scale and the known universe. universe. ‘1 TeV TeV (1,000,000,000,000 eV, where an optical photon has an energy of a few eV’ http://imagine.gsfc.nasa.gov/docs/science/how_l2/gamma_detectors.html http://imagine.gsfc.nasa.gov/docs/science/how_l2/gamma_detectors.html Smallest wavelength Quite rare. Only created by Only radioactive atoms and nuclear reactions. nuclear The hottest regions of the The universe produce them. universe Formed by Supernovae, Formed Pulsars, Neutron Stars, Black holes, and Gamma Ray Bursters. 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) electron volts.’ 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. was It picked up fewer than 100 cosmic gammaray photons total. CGRO satellite. The moon gives off more Gamma Rays The than the sun. than Mirrors don’t work How Do We See Gamma? How 1-30 MeV Is the ideal range that we wish to 1-30 see. see. Active galaxies, pulsars, and solar flares. Compton Scattering and how it works. Compton How Do We See in Gamma? Continued… How I’m a visual person… http://learntech.uwe.ac.uk/radiography/RScience/interactions/comptonscatter.htm So How Does That Work Again? Again? Crystal Scintillators Crystal Crystals that emit low energy light (usually visible) when hit by high energy light such as gamma radiation. such Pair Production Pair The physical process whereby a gamma-ray photon, usually through an The interaction with the electromagnetic field of a nucleus, produces an electron and electromagnetic an anti-electron (positron). The original photon no longer exists, its energy an ). having gone to the two resulting particles. The inverse process, pair annihilation, creates two gamma-ray photons from the mutual destruction of an electron/positron pair. http://imagine.gsfc.nasa.gov/docs/dict_jp.html#pair_production http://imagine.gsfc.nasa.gov/docs/dict_jp.html#pair_production CGRO uses compton scattering and pair production. CGRO Launched in April 5th, 1991 on Atlantis shuttle. Had a visual range of 30 KeV to Launched 30 GeV 30 Burst And Transient Source Experiment (BATSE), the Oriented Scintillation ), Spectrometer Experiment (OSSE), the Imaging Compton Telescope Spectrometer ), (COMPTEL), and the Energetic Gamma Ray Experiment Telescope ( EGRET). ). http://cossc.gsfc.nasa.gov/ 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. universe More energy in 10 seconds than our More sun can produce in its entire liftime of 10,000,000,000 years! of GLAST GLAST Gamma-Ray Large Area Gamma-Ray Space Telescope Large Area Telescope Telescope Funded Jointly by the US, Funded 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 Telescope Experiment 80° Field of View Launched in 1991 as an Launched Experimental Program Experimental Re-entered in 2004 Major EGRET Discoveries Major The finding of a new class of objects--high The energy gamma-ray emitting blazars, or grazars The emission of high energy gamma-rays from a The 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 The pulsar electromagnetic radiation going into gamma rays as the age of the pulsar increases to a million years The determination with high certainty that The cosmic rays are galactic The detailed mapping of the galactic diffuse The radiation and the measurement of the pion bump in the high energy gamma-ray spectrum The absence of microsecond bursts and its The implication for certain unification theories The long trapping time of over ten hours for The energetic solar particles following a flare A measurement of the diffuse, presumably measurement extragalactic, high energy gamma ray spectrum extragalactic, http://lheawww.gsfc.nasa.gov/docs/gamcosray/EGRET/highlights.html INTERGRAL INTERGRAL International Gamma-Ray International Astrophysics Laboratory Astrophysics European Space Agency European Demark, France, Germany, Italy, Demark, Spain and Switzerland Spain + Czech Republic and Poland With help from Russia and US Giant molecular Giant cloud in the center of the galaxy that was just recently discovered discovered Gamma-Ray Burst over 40 Seconds Gamma-Ray http://www.rssd.esa.int/Integral/integ_images.html A Cool Picture !!! Cool Sources Sources http://imagers.gsfc.nasa.gov/ems/gamma.html http://science.nasa.gov/newhome/headlines/ast09feb99_1.htm http://www.wordiq.com/definition/Gamma_ray_burst 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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