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Q & A: Annihilation phenomena and anti-matter atoms

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Most recent answer: 01/02/2013
Q:
Can different particles and antimatter particles eliminate each other? IE a positron eliminate a proton or do they only eliminate their counterpart? Also, if we make antimatter particles in a lab, can an antimatter atom be sustained?
- Christopher Felix (age 35)
Tustin, Ca. USA
A:
The answer to your first question is no.  For annihilation to occur all quantum numbers of the two particles must be equal in magnitude with opposite signs.  Both a positron and a proton have electronic charge +1, so that doesn't work. Secondly the positron has a property called lepton number, which is + one.  The proton has a property called baryon number, which is + one.  Its lepton number is 0.
Many experiments have shown that both lepton number and baryon number are separately conserved.  Thus a positron could not annihilate with a negatively charged antiproton even though charge conservation would be satisfied. 
The answer to your second question is yes.   You can form anti-hydrogen by mixing positrons with some anti-protons.   This has been demonstrated at the CERN accelerator laboratory in Switzerland.   You can get positrons from a strong beta decay source.  The anti-protons come from the high energy accelerator at CERN.  Many properties of anti-hydrogen should be identical to those of regular hydrogen atoms such as the magnetic moment, total mass, etc.   These predictions have been verified.

LeeH
 

(published on 01/02/2013)

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