First Solid Sign that Matter Doesn't Behave Like Antimatter

[Dryson]

One of the biggest mysteries in physics is why there's matter in the universe at all. This week, a group of physicists at the world's largest atom smasher, the Large Hadron Collider, might be closer to an answer: They found that particles in the same family as the protons and neutrons that make up familiar objects behave in a slightly different way from their antimatter counterparts.

While matter and antimatter have all of the same properties, antimatter particles carry charges that are the opposite of those in matter. In a block of iron, for example, the protons are positively charged and the electrons are negatively charged. A block of antimatter iron would have negatively charged antiprotons and positively charged antielectrons (known as positrons). If matter and antimatter come in contact, they annihilate each other and turn into photons (or occasionally, a few lightweight particles such as neutrinos). Other than that, a piece of matter and antimatter should behave in the same way, and even look the same — a phenomenon called charge-parity (CP) symmetry.

http://www.space.com/35857-first-sign-matter-and-antimatter-difference.html


Is it possible to create a block of iron with negatively charged anti-protrons and positively charged anti-electrons where the iron would still retain its molecular cohesion?

Or would an exchange between the two iron blocks have to take place at the instant the energetic reaction was needed to occur?

 

[Asbo Zaprudder]

Is it possible to create a block of iron with negatively charged anti-protrons and positively charged anti-electrons where the iron would still retain its molecular cohesion?

No, we can only create antiprotons and positrons. We haven't created any antineutrons deliberately (it isn't easy to handle and contain even ordinary matter fast neutrons as they have no charge) and, even if we had a way of creating and containing antineutrons, we have no way to fuse antiprotons and antineutrons into the nucleus of an atom of anti-iron. You'd probably need a massive star composed of antimatter and wait for it to spill its core contents during a supernova explosion. You'd likely have difficulty machining solid anti-iron, however. Perhaps you could use laser-based techniques to contain and shape the material.

http://physics.stackexchange.com/questions/134252/how-to-create-antineutrons
A scheme for the preparation of a polarised antineutron beam
https://en.wikipedia.org/wiki/Supernova_nucleosynthesis

Or would an exchange between the two iron blocks have to take place at the instant the energetic reaction was needed to occur?

I don't understand the question. What do you mean by "needed to occur"? A pair of iron and anti-iron blocks would likely blast themselves away from each other due to the energy released as gamma rays and neutral and charged pions due to electron-positron, neutron-antineutron and proton-antiproton annihilation between the contacting surfaces. Easier to use bare protons and antiprotons, which are charged and so can be manipulated using EM fields. Supposedly, one can obtain useful thrust only from the charged pions, which make up 60% of the annihilation energy.

One simple design [of M-AM engine] is based on the NERVA nuclear rocket, with the nuclear reactor replaced with a tungsten heat exchanger core. The reaction products (both gammas and pions) would be stopped in the tungsten and the energy used to heat hydrogen gas passing though the heat exchanger. This engine would use 13 µg/s of antiproton fuel to produce a specific impulse of 1100 s at a thrust level of 4.4x105 N (100,000 lb) for a power level of 2.7 GW. Such an engine could take 100 tonnes of payload to Mars and back in six months (only three months each way) with a mass ratio of 4. By comparison, a LOX/hydrogen system would require a mass ratio of 18 and would take 12 months to get there and 9 months to get back.

Antiproton Annihilation Propulsion (AFAL TR-87-070)
Antiproton Annihilation Propulsion (AD-A 160 734)
Physics of Antimatter-Matter Reactions for Interstellar Propulsion