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Q & A: bosons made of fermions

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Most recent answer: 05/17/2011
Q:
From my understanding, protons and neutrons are composed of quarks, which are fermions. My question is why are alpha particles bosons?
- Dylan (age 18)
Belleville, IL, US
A:
Alpha particles (2 protons+2 neutrons) have an even number of fermions. Therefore they're bosons.

A boson is a particle whose wave function remains the same under rotation by 360. A fermion is a particle whose wave function changes by a factor of -1 under 360 rotation. The combination of an even number of them changes by -1 to an even power, i.e. 1, so that's a boson.

Mike W.

(published on 05/17/2011)

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