What is the shape of a deuterium nucleus?
I can think of two obvious extremes.
A positive proton end intersecting with a neutral neutron end.
Or a cylinder with spherical caps on the ends that is positive on one end and neutral on the other.
Answer
This is an extended comment on count_to_10's answer, please upvote that answer not this one.
It's tempting to think that because a deuterium nucleus is made up from two different particles, one positive and one neutral, that it must necessarily be asymmetric. However a hydrogen atom is also made up from two different particles, one positive and one negative, and it is spherically symmetric. The reason for the spherical symmetry of the hydrogen atom is that the proton and electon are both delocalised.
The same argument applies to the deuterium nucleus except that the strong nuclear force is not a central force but depends on orientation, so we should not expect spherical symmetry. There won't be one end of the nucleus that is the proton and the other end that is the neutron because both particles are delocalised. In fact, as count_to_10 describes, the deuterium nucleus is axially symmetric and centrosymmetric. This means the two ends are identical - there is not a neutron end and a proton end.
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