Anti-matter and neutrons.

[Daecon]

Would an anti-matter atom need to have an anti-neutron in it's nucleus?

 

Could it be physically possible to have an atom of anti-matter with matter neutrons in it?

 

For example, anti-helium with two anti-protons and two "standard" neutrons orbited by two positrons?

[insane_alien]

I don't think so because the quarks/antiquarks would probably annihilate but you'll want to check this against someone who knows more about this than me.

[aguy2]

Would an anti-matter atom need to have an anti-neutron in it's nucleus?

 

Could it be physically possible to have an atom of anti-matter with matter neutrons in it?

 

For example' date=' anti-helium with two anti-protons and two "standard" neutrons orbited by two positrons?[/quote']

 

Aren't neutrons considered to decayed protons?

If so wouldn't anti-neutrons be decayed anti-protons?

aguy2

[5614]

Neutrons can decay into protons (and in the process release an electron and a anti-neutrino).

 

So an anti-neutron would decay into an anti-proton (and in the process release a positron and a neutrino) - basically the whole neutron decay (aka beta decay) in reverse.

 

Whilst I can't say the following with certainty I would agree with insane_alien that an anti-atom could not exist with neutrons in the nucleus because the quarks would annihilate each other.

 

By definition an anti-atom must be made up of only antiparticles, however that doesn't mean it wouldn't be stable (ie. possible) to have a combination based on the definition alone. However, like I said above, I don't think it would be possible.

[Meir Achuz]

If there were any particles (other than anti-particles) in an anti-nucleus, lit would instantly annihilate.

[NeonBlack]

Say you had an anti-neutron and a proton. If I remember right, a proton has two up quarks and 1 down quark, and an anti-neutron would have 2 anti-downs and 1 anti-up. Assuming the individual quarks annihilated, that would leave what? An up quark and anti-down quark? I suppose it seems possible, and charge is conserved, so there's no problem there.

But as far as I know, quarks have never been observed to exist individually, so it would really suprise me.

I don't know. Hopefully someone who knows something will help us out here.

[swansont]

If there were any particles (other than anti-particles) in an anti-nucleus, lit would instantly annihilate.

 

I don't think "instantly" is correct. Mesons are made up of quark-antiquark pairs, and they have finite lifetimes. I suspect that a proton-antineutron would split up into pions, which would then give you muons, neutrinos and gammas, and then the muons would decay.

[Meir Achuz]

I don't think "instantly" is correct. Mesons are made up of quark-antiquark pairs, and they have finite lifetimes. I suspect that a proton-antineutron would split up into pions, which would then give you muons, neutrinos and gammas, and then the muons would decay.

My dictionary says "soon to happen, imminent", but I don't want to nitpick.

[swansont]

I don't think they'd annihilate, either.

[Meir Achuz]

I don't think they'd annihilate, either.

Sorry, but I have to ask who are "they", and what does "either" mean in this context?. I understand the other words.

[swansont]

Sorry, but I have to ask who are "they", and what does "either" mean in this context?. I understand the other words.

 

My guess is that you'd form mesons from your antiproton+neutron, as per my previous post; it would be neither instantaneous, nor would you have annihilation, at least in the sense of forming two gammas.

 

(If my posting has been muddled please forgive me, I have a cold.)

[Meir Achuz]

"Annihilation" is not only to photons.

Hadronic annihilation is rarely to photons, but usually to mesons.

In HEP "instantaneous" generally means faster can be measured.

For instance the \Delta++ which has a width of about 120 MeV

(giving it a lifetime ~ 10^-23 sec) is said to decay instantaneously.

If an antineutron struck a nucleus (or neutron an antinucleus) , the annihilation would be faster than this.

Gezundheit.

[SmallIsPower]

I'd think a single quark/antiquark pair would annihilate, creating an explosion that would blow the rest of this hybrid atom to bits, becacause there would be more enrgy released than in the oppsite fusion reaction(which converts 1% of the mass or less.)

[insane_alien]

Small: quarks and antiquarks form a particle called a meson. this happens cause there are different types of quarks.

[swansont]

I'd think a single quark/antiquark pair would annihilate, creating an explosion that would blow the rest of this hybrid atom to bits, [b']becacause there would be more enrgy released than in the oppsite fusion reaction(which converts 1% of the mass or less.)[/b]

(emphasis added)

 

Can you explain what you mean by the bolded part?