Positron Cannon
From Conworld
- This article discusses a possible weapons development in the future. Calculations verified by Ketsu.
- STATUS: DIAGRAMS TO BE ADDED
- // Ketsu Drop a MsgAlex 09:39, 21 August 2007 (EDT)
Contents |
Projectile: The Positron
(Quotes from various sources)
The positron is the antimatter/antiparticle counterpart to the electron. The positron has an electric charge of +1, a spin of 1/2, and the same mass as an electron. When a low-energy positron collides with a low-energy electron, annihilation occurs, resulting in the production of two gamma ray photons.
Positrons may be generated by positron emission radioactive decay (a weak interaction), or by pair production from a sufficiently energetic photon.
Today, positrons are routinely produced in positron emission tomography (PET) scanners used in hospitals and in accelerator physics laboratories used in electron-positron collider experiments.
Usability: The Electron-positron annihlation
(The following diagrams are hand-drawn and may not be to scale.)
Obviously, this reaction has to observe current laws of physics, most notabily the series of conservation laws.
- Conservation of charge. The charge before and after the reaction must be zero.
- Conservation of linear momentum, angular momentum and total energy. Thus, a single gamma ray may not be emmited.
Also, the electron and positron may not react, due to the "elastic scattering"-effect. More information: [1]
Most likely case for low engery: Dual gamma rays
Two photons are created, releasing energy theoretically equal to the rest energy of an electron/positron (about 511 keV, using Einstein's famous formula) as two protons. (Note: One electronvolt(eV) is equal to 1.602 176 53 (14) x 10�19 J)
Less likely case for low energy: Multipule gamma rays
Not very likely as more complex processes involving lower quantum mechanical amplitudes are required in the reaction.
High energy collision
Basically, more massive particles can be produced, for example, the W-/W+ pair, which is relatively rare.
What basically happens
Electron + Position collide, destroyed, releasing large amounts of energy.
How: The Positron Cannon
(The following diagrams are hand-drawn and may not be to scale.)
QUOTE: "Pair creation involves collisions with high enough energy that an electron-positron pair can be formed."
As stated before, the rest energy of an electron/positiron is about 511 keV, by Einstein's famous formula, Failed to parse (Can't write to or create math temp directory): e = mC^2 . Therefore, a surplus of energy of at least 1022 keV is required for pair creation to take place.
Lol, this method of creating positirons is more technically compilcated than the other method.
QUOTE: "Positrons may be generated by positron emission radioactive decay."
This is the method that we think will most likely be implemented in the future. You only need an isotipe of the right kind, and you're off. As we all know, in radioactive β decay, what is really emitted is a high energy electron; this is more accurately discribed as β- decay, as it's an electron. There are a few isotopes that decay by β+ decay, which is similar to β- decay, just that a high energy positrion is released. Na-22 is a well-known isotope for the purpose, and also has a roughly perfect half-life of 2.6 years, which is long enough to not have to reload very often, and is short enough so that the reactivity is high enough.
One problem that you might notice if you've been paying attention during those physics lessons (>_< to you all), is that the postions would be of widely varying energies. (Damn decay.) Okay, in order to make that damn positron beam, you have to have a narrow energy spread, narrower the better. (Try thinking about it.) So what do you do? You grab materials that would absorb some of the positron's energy if it's too great - these materials would be those that hold electrons very well. Think chemistry and the answer would hit you like a flying brick --- SOLIDS!!!
Buried somewhere in this article is the fact that Neon is very good at slowing down and "emmiting" (as in re-surfacing) positions. Using a piece of Neon solid of suitable thickness you can produce a mono-engenic (how-ever you spell that) postiron beam. Using a magnetic field, you can guide this beam.
Bingo, that is a general overview of the construction of a Positron Cannon.
Problems: And their solution
Unfortunately, Neon is a gas a room-temperature. This fact should not be a problem in space, where temperatures are usually at near-zero K temperatures, perfect for solid Neon. However, this makes atmospheric combat (and maybe even flight in the atmosphere, because the Neon would melt) using such a weapon impossible if you rely on the external temperature being so low.
Also, more efficent positiron "emmiters" must be found, coz Neon has a 3-4% efficency. With a source strength of 40 mCi we end up with a positron beam of about 5 million positrons per second.
Improvements: Possibily in the future
Adding a "charging" ability to the cannon to allow it to release bursts of positrons.
This is possible by accumulating the positrons in an accumilator-like device.
Section incomplete
