How different would matter-antimatter explosion be compared to nuclear


by Hurricane93
Tags: antimatter bomb, fireball, nuclear, particle decay
Hurricane93
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#1
Aug12-13, 09:51 AM
P: 19
Would the antimatter explosion still make a fireball and thus a blast wave ?
If so, then how will the fireball form in this case ?

I mean, matter and antimatter annihilation produce very energetic pions, muons and gamma rays
and some other particles after decaying depending of course on which particle is annihilated. The gamma rays for example are in the 100+ MeV range which is much more compared with the ones we get from fusion for example and so, it has a shorter wavelength, thus penetrating materials easier.

So now, as we all know, nuclear fireball is formed when the energy of the particles are released into the air in a very short time, heating it up and causing these atmospheric changes or "blast" as we call it.

In the case of these very high energetic particles we get from the annihilation, is the same thing going to happen ?
In another way, because the energy of these particles is too high, it will likely travel more in the atmosphere until it loses enough energy to heat the air up, and thus taking much longer times, and therefore, no fireball !

How true can that be ? Am I missing something ?
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mfb
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#2
Aug12-13, 11:01 AM
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The bomb shell would absorb a significant fraction of the released photon energy and lead to a fireball afterwards.
If the bomb is big enough, absorption in air (or even decays of muons, if the bomb is big enough) will give a very large, very hot region of air, so you get an even larger fireball.
Old thread with some numbers
Hurricane93
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#3
Aug12-13, 11:20 AM
P: 19
Quote Quote by mfb View Post
The bomb shell would absorb a significant fraction of the released photon energy and lead to a fireball afterwards.
If the bomb is big enough, absorption in air (or even decays of muons, if the bomb is big enough) will give a very large, very hot region of air, so you get an even larger fireball.
[ul=http://www.physicsforums.com/showthread.php?t=640940]Old thread with some numbers[/url]
Well, this is some quote I found in the link you gave me :

"Does it mean that the energy of annihilation explosion can be spread out over a large volume of air, not concentrated near the original location of antimatter?

Looks like that."

So, if the explosion or the heat in other words is spear over a large volume, would that still make a nuclear-like explosion ?
Also, how thick should the bomb be to do what you suggest ? and if the pions decay, does that mean their energy doesn't contribute to the explosion so we have to get their energy before decay ?

mfb
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#4
Aug12-13, 12:45 PM
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How different would matter-antimatter explosion be compared to nuclear


Also, how thick should the bomb be to do what you suggest ?
To absorb most photons from neutral pions, something like 10cm of steel should be sufficient. The result would be similar to a conventional nuclear weapon.

and if the pions decay, does that mean their energy doesn't contribute to the explosion so we have to get their energy before decay ?
Charged pions release their energy mainly via nuclear interactions or via the decay to a muon and two neutrinos. The relative fraction depends on the amount of material they have to pass.
Assuming the bomb is not close to the ground, most muons will decay within ~2km, and the resulting electrons will quickly lose their energy and heat the air.
I don't think this gives a well-shaped fireball, but it can heat air significantly. It takes approximately 4MT of TNT-equivalent to heat such a volume (with 2km radius) by 500K. The air close to the bomb will certainly get really hot for MT-scale bombs.
Hurricane93
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#5
Aug12-13, 02:31 PM
P: 19
Quote Quote by mfb View Post
Charged pions release their energy mainly via nuclear interactions or via the decay to a muon and two neutrinos. The relative fraction depends on the amount of material they have to pass.
Assuming the bomb is not close to the ground, most muons will decay within ~2km, and the resulting electrons will quickly lose their energy and heat the air.
I don't think this gives a well-shaped fireball, but it can heat air significantly. It takes approximately 4MT of TNT-equivalent to heat such a volume (with 2km radius) by 500K. The air close to the bomb will certainly get really hot for MT-scale bombs.
Ok. So to get a conclusion here, gamma rays will need something to absorb them in a little time and a little space to make a fireball. Charged pions are unlikely to form a well-shaped fireball either before or after decay. What about uncharged pions ?
mfb
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#6
Aug12-13, 02:43 PM
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Uncharged pions lead to gamma rays.


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