[SOLVED] Hybrid Atoms

josetrimarchi

I should like to know your opinion about the possibility of the existence of atoms whose nuclii are composed of matter and antimatter components (simultaneously).
Which and where experiences had been made about it. Thank you.

dextercioby

U mean,antiprotons and antineutrons??I don't know of any experimental evidence,but let's discuss its theory...Question:what are the differences between an exotic nuclei and a "normal" one??

Daniel.

Haelfix

Google for positronium if your interested, they are real and have been observed. Its really a temporary state of course and is highly unstable.

Its the analogue of a hydrogen atom, where a positron and an electron interact via the coulomb field.. It has several decay modes, either a photon or 3 photons will come out.

Of course heavier antimatter atoms have halflifes that are even smaller, so experimentally they are challenging.

LURCH

If I am reading the original post correctly, the question is not about an antimatter atom (like positronium), but an atom made of both matter and antimatter. I cannot see how such an atom would even be possible. I think that if a proton and an antiproton get close enough to form an atomic nucleus, they will annihilate one another.

know-it-all

Despite the common process of increasing atomic number by means of succesive fusion processes (i.e.: H + H = He, He + He = C, etc.), I think we must to take into account the fact that atomic weight can increase by particle capture processes.
Then, if an antihydrogen atom captures a neutron, the result is an exotic antideuterium atom carrying at its nuclii a neutron instead of an antineutron.
According to my actual knowledge (if someone knows it better I'll be gratefully indebted if you post, at this thread, the adequate reply) an antineutron can be annhilate only through close interaction with a neutron. Then, a neutron could be captured by antihydrogen nuclii, resulting in a exotic (or hybrid) antideuterium atom.
Remember that chemical properties of an (anti-)atom if given by its (anti-)electrons, and the atomic mass is carried by its nuclii.
Previous scenery is only possible if short range nuclear interaction is of the same nature between particles and antiparticles (or nucleons and antinucleons).

Know-it-All

Pyrovus

Unfortunately, you would most likely get partial annihilation between the antiproton and the neutron. An antiproton is comprised of 3 antiquarks; 2 up antiquarks and 1 down. A neutron is comprised of one up quark and two down quarks. As a result, the up quark of the neutron would annihilate with one of the up antiquarks of the proton, and one of the down quarks of the neutron would annihilate with the down antiquark of the proton, leaving behind a meson composed of what's left over, an up antiquark and a down quark.

However, I guess it might be still be possible to form a hybrid atom with, say, an antiproton and some nucleon containing eg. strange quarks, which will not annihilate with the quarks of the antiproton.

josetrimarchi

Dear Know-it-all,
I totally agree with those concepts developed by you.
The trouble is the fact that if matter nuclii capture anti-neutrons, they should annihilate it, and the atom would dissappear.
It will occur the same when antimatter capture a neutron.
As our question was if hybrid atoms exists, your answer is that they can not exist, or annihilations and creations are simultaneous.

My best regards,
Sincerely
Jose Trimarchi

bbtuna

Nitpick (I study positromium formation at work):

Haelfix wrote:
"It has several decay modes, either a photon or 3 photons will come out."

There are really two types of Positronium (Ps): orthopositronium (o-Ps) and parapositronium (p-Ps). They each decay in a different way. For o-Ps, the spins of the positron and electron are parallel to eachother, giving a net spin of 1 to the atom. In order to conserve momentum and spin, 3 photons (each having spin 1) are emitted. Their total energy it 1022 keV (rest mass of Ps).

For p-Ps, the spins of the electron and positron are anti-parallel, giving a net spin of 0. So p-Ps decays by two photons in order to conserve momentum and spin. Each photon has an energy of 511 keV and they travel in opposite directions. A single photon decay will not conserve momentum in either case.

Granted, more than 2 or 3 photon decays can occur, but they are very, very rare (something like 1 decay per 1,000,000 will give a five or four photon decay for each, o-Ps and p-Ps respectively).

zefram_c

Unfortunately, that would not work either, since an anti-strange quark can still weakly interact with an up quark and form an electron/neutrino pair. Personally I don't think any nuclei of the proposed type can be formed.