How much energy is there in gamma radiation?
Seems like each particle should have some mass and a bunch-o-velocity so whay can’t/don’t we harness it? Is there anything like a photovoltaic cell that can be used with this stuff to make 'lectricity? For example, if you don’t have a warhead handy you really have no options for your 3 pounds of plutonium other than to bury it someplace. Could this stuff be “used” in any productive way?
Asking “how much energy is there in gamma radiation?” is rather like asking “how long is a piece of string?”
Radioactive decay (which includes alpha and beta particles as well as gamma photons) can be and is harnessed: we call the device that harnesses it a radioisotope thermoelectric generator (RTG). It typically uses a plutonium isotope with a half-life measured in years (such as [sup]238[/sup]Pu, half-life 87.7); it’s favored for long-duration missions which goes out beyond the asteroid belt, where solar energy is too dilute for use. You may recall the nutcases^H^H^H^H^H^H^H^H environmentalists protesting its use in the Galileo probe.
[sup]239[/sup]Pu, as used in nuclear weapons, has a half-life of 24,110 years, too long to use in an RTG (the power density is too low). It is being reprocessed by use in mixed-oxide reactors.
Not at all. In fact every photon, gamma or otherwise, has a well-defined energy level which is given by E = h [sup].[/sup] f, where E is energy, h is the Planck constant and f is the frequency of the EM radiation. For a typical gamma ray with a wavelength of 1 x 10[sup]-12[/sup] m, the frequency is 3 x 10[sup]20[/sup] Hz. Since h is equal to about 6.34 x 10[sup]-34[/sup] Js, that works out to an energy of 1.902 x 10[sup]-14[/sup] J per gamma photon.
Here’s a perfectly good use for Gamma Rays:
Laser/Gamma Ray based nuclear transmutation
Very powerful gamma ray photons from outer space can carry as much energy as a fast-pitch baseball, though it’s rare.
The term “gamma” can imply an energy between x-rays and cosmic rays, or can imply that the origin is an atomic nucleus transition. Similarly, x-rays can imply that the origin is an electron tube and cosmic rays generally implies an extraterrestrial origin (as well as including particles other than photons).
Anything that absorbs gamma rays will convert their energy to heat (and perhaps other things like secondary radiations of various kinds). And, pretty much any kind of matter will work as the absorber, though you need more or less and get different kinds of secondary radiations depending on your choice.
If you have 3 pounds of plutonium, and wrap it in something to trap radiation (I think Plutonium emits primarily alpha radiation which is very easy to trap), it will generate enough heat to keep a pot of water boiling vigorously for decades, and gradually less vigorously for centuries, if you keep adding more water. Surely you can do something amusing with that.
I think I remember reading something about that. I believe it was called the OH-MY-GOD!!! particle. it supposedly had the energy of a rock thrown at 14 miles per hour. When I read about it I had this image of a scientist chocking on and then spitting coffee all over a report they were reading.
But if you don’t know the frequency (or the reaction), you don’t know the energy. All you can say is a gamma typically has more than ~0.5 MeV of energy.