Magnetic Field & Particle Spin: Does It Matter?

[synch]

Does the magnetic field caused by moving particles depend on the particle spin value?
Eg a stream of say protons spin 1/2 is creating a magnetic field. If the particles are (say) lithium nuclei spin 3/2 instead, does that create the same strength field ? (same conditions of course)

 

[kuruman]

Eg a stream of say protons spin 1/2 is creating a magnetic field.

Do you think that this magnetic field arises from the, presumably, aligned spins of the protons in the beam or from the current generated by the moving charged particles?

 

[synch]

[Will the spins be aligned in a weak field? .]

The standard logic goes, magnetic fields are typically created by moving charge, and so on. But charge always seems to be associated with spin, so there is also spin involved. Hence my question regarding using changed spin .
In general I am wondering if a magnetic field might be better described as a spin field - it makes more sense to me at least, ( qualitatively). That would maybe make the classical "lines of force" more sensible as directrices of resultant force or similar.

This might be better at the intermediate level, - it is long time since I did physics, hopefully it is a sensible question :)

 

[PeroK]

[Will the spins be aligned in a weak field? .]

The standard logic goes, magnetic fields are typically created by moving charge, and so on. But charge always seems to be associated with spin, so there is also spin involved. Hence my question regarding using changed spin .
In general I am wondering if a magnetic field might be better described as a spin field - it makes more sense to me at least, ( qualitatively). That would maybe make the classical "lines of force" more sensible as directrices of resultant force or similar.

This might be better at the intermediate level, - it is long time since I did physics, hopefully it is a sensible question :)

Technically the spin of an electron is quantum mechanical. If we treated the electron classically, then in the rest frame of the electron we would have the electromagnetic field associated with a spinning ball of charge. Which we could transform to the frame in which the electron is moving.

I'm not sure of the qualitative significance of the spin in this case. And, of course, the magnetic dipole moment of the electron is twice that calculated from classical electrodynamics. See, for example:

http://hyperphysics.phy-astr.gsu.edu/hbase/spin.html

 

[kuruman]

But charge always seems to be associated with spin, so there is also spin involved.

Not always. Neutrons have spin but they have no charge. As far as I know, there are no magnetic fields associated with neutron beams.

 

[PeroK]

Not always. Neutrons have spin but they have no charge. As far as I know, there are no magnetic fields associated with neutron beams.

In classical EM, the neutron should have no magnetic dipole moment (at least if we consider it as an elementary particle). But in the quark model, it does have a measurable magnetic dipole moment.