Air Force Researching Antimatter Weapons

mlmitton writes "The San Francisco Chronicle is reporting that the Air Force is actively pursuing antimatter weapons. Such weapons would easy eclipse nuclear weapons in power, e.g., 1 gram of antimatter would equal 23 space shuttle fuel tanks of energy. Perhaps more interesting, after an initial inquiry by the Chronicle in the summer, the Air Force issued a gag order that prohibits any Air Force employee from discussing antimatter research or funding."

Comments

Medical (Peaceful) Uses of Positron

[abcho]

For a balanced view, it is important to realize that anti-matter physics have yielded substantial medical and non-military benefits already. Many people probably already encountered various applications of this technology without realizing it.

For example, Positron Emission Tomography (PET) is a very useful clinical and medical research tool for brain and cardiac functional imaging. See: Positron Emission Tomography

Re:Energy Conversion

[abb3w]

1 kg antimatter mixed with equal matter yields about 42 megatons, half from matter conversion to energy, half from antimatter conversion to energy. The energy would initially be in the form of gamma rays at the neighborhoods of .5 and 900 MeV, but the latter would self-scatter (? correct term ?) due to electron positron emission/annihilation, and head down REAL fast towards the .5 MeV.

Still a hell of a chest X-ray to give the planet.

Re:How about research them...

[pz]

Uh, basic physics, people. The Universe is comprised of matter, not anti-matter. You can make anti-matter, but it takes a heapload of energy (recall that E=mc^2 applies to anything that has mass), and you cannot go out and mine anti-matter. Why? Mostly because if there were any antimatter around, it would have a nasty tendency to interact with all that matter and be converted to energy.

So, you can use it to create a nice bomb, but it's equivalent to pumping up a pressurized bottle with a lot of air -- the only energy that's going to come out is the energy that you've put in to create the anti-matter. You make some anti-matter, find a way to confine it and later release it in a controlled fasion and you get a very nice bomb which is incredibly powerful given the mass of the active ingredients. But you cannot use it as an energy source because unlike coal, oil, natural gas and uranium, it isn't freely available: you have to make it.

This is in stark contrast with nuclear fusion and fission: there is lots of available material lying around in the ground and in the seas, just waiting to be extracted and used. While you can find ways of generating anti-matter without putting too much energy into the process (eg, by triggering nuclear decay) you just don't get that much mass very quickly. Unless, of course, you've got a right raging nuclear reaction going, and, then, well, your problems of bomb making are pretty well solved.

Wrong kind of radioactive

[weedenbc]

Anti-matter weapons are radioactive in the same way as neutron bombs - a burst of gamma radiation. But they are NOT like fission bombs in releasing radioactive particles.

In a fission reaction the fallout comes from two sources. The first is the by-products of the fission reaction. I believe it is radioactive isotopes of Cesium and Potassium. This radioactive particles combine with the uranium/plutonim that did not fission and get distributed as fallout.

A pure fusion bomb, e.g. neutron bomb, has only a fusion reaction and thus theoretically produces no radioactive fallout. However in practice a fission reaction is used to create the pressure and heat needed to start the fusion reaction.

See the Special Weapons Primer at http://www.fas.org/nuke/intro/nuke/index.html for more info.

Re:Wrong kind of radioactive

[Blethrow]

A neutron bomb will also generate a ton of local radioactivity by neutron capture activation of nuclei in the immediate environment. Most of this will be pretty short lived.

Re:Energy Conversion

[SeanTobin]

You had to ask didn't you? Well, I asked google how many burning libraries of congress(es?) in one gram of antimatter... And google was stumped :(

So, here we go... 1 gram of antimatter -> burning libraries of congress(es?):

For the sake of argument, lets assume that the Library of Congress is entirely non-flamable and only the books contribute to the heat. Furthermore, lets assume that all the books are made of 100% wood or equivilant.

Now, 1 gram of wood when completely burned produces 3000 calories.

The Library of Congress contains approximately 128 million items. Again, some of these are recordings of various natures and will not burn as well as books... so to compensate we'll deviate from our initial assumptions and assume that the burning of the 530 miles of bookshelves compensate for any lack of flamability of the old records.

So... our average paperback weighs under 1lb and our average hardcover book weighs between 1 and 2lbs. Seems reasonable enough. Lets assume a distribution between hardcover and paperbacks so as the average book weight in the LOC is 1lb.

Now, Google can help us some more here. Our friendly search engine lets us know that one pound is 453.59237 grams. We'll round that off to 453 grams, since we're averaging book weight anyway.

So, the LOC has (453*128,000,000) or 57,984,000,000 grams worth of books. At 3000 calories per gram, burning down the LOC would produce 173,952,000,000,000 calories of energy. For the sake of sanity, lets convert that to joules. Google says that 173 952 000 000 000 calories = 7.27815168 × 10^14 Joules

Now, our space shuttle main tank (and engines, NOT including boosters which are more powerful) produce 1,987,500,000 Watts of energy, and burn for 8.5 minutes. That's (510*1,987,500,000) 1013625000000 Watt/seconds of energy. Converted to joules, that is remarkably 1013625000000 Joules.

So.. One space shuttle fuel tank of energy is 1013625000000 Joules. 23 space shuttle tanks of energy is 23313375000000 Joules. For convienence, one space shuttle tank is 0.23313375x10^14 joules.

So... it comes down to one burning LOC is 7.27815168 × 10^14 joules. 23 space shuttle fuel tanks are 0.23313375*10^14 joules. So, one gram of antimatter combining with one gram of matter is approximately 0.032 Burning Libraries of Congress(es?). I actually expected it to be more.

Now how do I get Google to include space shuttle fuel tanks and burning libraries of Congress(es?) as acceptable measurements?

Re:Plutonium

[Muhammar]

Here you mixed details from 2 related stories: Daghlian accident during the war and Slotin accident after the war. The accidents happened with the same plutonium sphere. Slotin was boss of Daghlian and saw him dying. He had very similar accident and died in the same hospital room 9 months later. This Pu sphere was stored for safety reasons as 2 separate hemispheres and these were put together before experiment. The accidents were caused not by combining the Pu hemispheres but by surrounding them with neutron reflector which turned the system critical.

Daghlian was trying to find the practical (=just barely subcritical) arrangement of cube of tamper material (tungsten carbide) which would be completely surrounding a solid 6.2 kg sphere of delta-phase of Pu239. The carbide bricks functioned as neutron reflector also. Daghlian was working very slowly as he was getting close to critical configuration (neutron reflection increased reactivity). One of the heavy bricks felt out of his hand - on top of the Pu sphere and the system went critical. Daghlian trew the brick quickly away and disasembled the system into more strable configuration, etc. He got just above letal dose so he was dying very slowly.

Slotin was demonstrating for his colleagues reactivity of Pu depending on reflection of neutrons from berylium cover (Be holow hemispheric cover surrounding Pu sphere which was sitting half-embeded within another large Be hemispheric stand). The Be cover slipped, enclosed the Pu sphere, the system went critical, there was flash, Slotin took it apart with his bare hands (to save his colleagues) and got huge dose which killed him few days later.