Antimatter annihilation "frequency"

The Nomad · Post by **The Nomad** » 2006-07-08 07:13pm

On another board, a poster commented that a matter/antimatter reaction will lack a specific 'frequency'.

My very first thought was :"BULLSHIT". Electron/positon reactions (at nonrelativistic speeds at least) will yield two gamma photons with a frequency of about 1E20 Hz. The collision of nuclei and antinuclei should produce photons of similarily set frequencies, if I'm not mistaken (if I am, then

). Neutrinos don't count, and pions will decay into more neutrinos and electrons, which do have a de Broglie wavelength (and therefore a frequency). Now my question is : are the pions' speed sufficiently homogenous to consider that they have a special "frequency" ?

Then comes the superheating and destruction of the remaining reactant and the casing of the device. Will the later reactions be influenced by the greater temperature and therefore produce different types of photons ? Will the radiation scattering of the casing further widen the explosion's spectrum ?

In essence I know that a "realistic" antimatter explosion will not have a specific X Hz frequency. But could its spectrum be approximated into a set of narrow [X-a;X+a] peaks ( say that 95% or somesuch of the energy is carried by photons and particles within this set of ranges), or will it be a wide spectrum ?

SWPIGWANG · Post by **SWPIGWANG** » 2006-07-08 07:40pm

I think it'd depends on the device being used. If we are talking about something that directly radiates the emission out it would probably fall within a narrow peak. I think we don't have too worry effects of high velocity particles as it is unlikely to react to each other when it is exploding out at energies that matter. If it is like a 99%matter to 1% anitmatter reaction to ensure efficiency (for a generator, for example), than we can probably go back to blackbody radiation formula.....

Kuroneko · Post by **Kuroneko** » 2006-07-08 08:31pm

The branching of electron-positron annihilation is dominated by two gamma rays, although it is not the only possible product, moslty because electrons and positrons do not ordinarily have enough energy to create much of anything else. That is no longer the case for proton-antiproton annhilation, which can have numerous products with a rather liberal distribution of branching ratios. Things are no longer simple. Nuclei/antinuclei reactions are most likely even more chaotic.

Post by **Darth Wong** » 2006-07-09 12:15am

The casing of the weapon would alter the output characteristics in any case, because any gamma rays will interact with it. You'll rapidly end up with a plasma shroud around the reaction.

SWPIGWANG · Post by **SWPIGWANG** » 2006-07-09 01:11am

If we consider the penetrative ability of gamma rays, wouldn't it simply penetrate matter most of the time without interacting, unless we are talking about thick and heavy casing? Even if it does turn rapidly into a ball of plasma, its emission could very well be only a tiny fraction of the total energy.

Post by **Beowulf** » 2006-07-09 02:54am

The leading edge of the gamma ray pulse ionizes the casing into a gamma ray opaque shell. Though, because it's not very thick, it doesn't stay intact for long. If in atmosphere, you end up with a much thicker shell, which means that much more will end up getting absorbed and re-emitted.