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Natural Science Forum / Physics / General Physics / May 2007High gamma energy source
I am trying to set up the experiment with the high energy gamma source which would be able to produce positrons in the material by use of the pair creation. I need to have a relatively high gamma energy for it. Are there any natural high energy gamma sources which have a half-life of at least days or weeks? I found only some short-lived sources in some of the natural decay series. They decay fast but at least they have longer lived parent isotopes. The only radioisotope with a relatively high energy and T1/2 which I found is Bi-208 E (gamma) = 2.614 MeV. Any other candidates? By the way, is there anyway the active nuclear physics discussion forum? Jagoda >I am trying to set up the experiment with the high energy gamma source >which would be able to produce positrons in the material by use of the [quoted text clipped - 13 lines] > >Jagoda For the isotope question you may want to join http://tech.groups.yahoo.com/group/CDV700CLUB/ http://tech.groups.yahoo.com/group/GeigerCounterEnthusiasts/ w. No, for what you seem to want, I really don't see you finding any natural sources. The isotopes that are employed for x-rays of welding joints, etc., are manufactured using reactors, are heavily controlled, and are very dangerous to employ. None are of natural origin. Harry C. On May 17, 1:46 am, j...@klaehn.myrf.net wrote: > I am trying to set up the experiment with the high energy gamma source > which would be able to produce positrons in the material by use of the [quoted text clipped - 13 lines] > > Jagoda >I am trying to set up the experiment with the high energy gamma source >which would be able to produce positrons in the material by use of the [quoted text clipped - 8 lines] > >Any other candidates? For obvious reasons, any naturally occuring sources with half lives of days/weeks (in fact with any half life short on geological scale) must be interim elements in decay chains originating with elements with half lives comparable or longer than geological time scales. You'll find few of these in the Uranium and Thorium decay chains. Mati Meron | "When you argue with a fool, meron@cars.uchicago.edu | chances are he is doing just the same" Guys, thanks for your help. I think, I was wrong with the idea of producing pairs from high energy gamma source. This is not really what I wanted to have as a high energy positron source. Yes, gamma will produce pairs but their production would be instantenous, there will be no any activation there and what I really wanted is to have activated probe. I found two other ways to do it - by a so called generator source which consist of long lifetime EC source which then decays to a high energy positron source which decays very fast. Another way is to use high energy alpha in (alpha,n) or (alpha, gamma) reaction. But the cross-section for such a reaction may be pretty low. |
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