Why does a cyclotron only impart linear momentum?

[bwana]

TL;DR Summary

Why is only linear velocity measured on alpha particles accelerated by a cyclotron?

I read the Wiki page

https://en.wikipedia.org/wiki/Electron_cyclotron_resonance

as well as this answer here

How does a cyclotron work?

and it describes a setup where one has a cyclotron which has a static magnetic field pointing up through the dees and there is an alternating high voltage across the dees. An alpha particle is attracted to a negatively charged plate so it moves towards the 'negative dee'. It moves in a circle because of the Lorentz force of the perpendicular magnetic field. When it gets around the semicircle, the voltage is flipped so now the particle jumps across and is accelerated from one dee to the other. I interpret this to mean that acceleration only happens when moving across one dee to the other. However, as the alpha particle is moving withing a dee, it is experiencing a force causing it to move circularly. Technically, the particle is being accelerated here too, but instead of acquiring linear momentum, it is acquiring angular momentum.

However, people smarter than me have said that alpha particles don't spin

Can the rotation of an alpha particle be measured?

Can someone enlighten me as to why alpha particles don't get angular momentum in a cyclotron?

 

[shjacks45]

"Centrifugal force". Newton's Law "object in motion ..." in the "dee", the magnetic field acts as centripetal force. When particle is out of dee it goes straight because no other force is on it. Because 2 neutrons and 2 protons the alpha cancels out nuclear magnetic resonance. Nucei rotation?

 

[mfb]

Even if alpha particles would have a spin: That's a particle property, you can't increase that spin. The direction of that spin can change, although it typically won't align itself with the external field on its own.

Technically, the particle is being accelerated here too, but instead of acquiring linear momentum, it is acquiring angular momentum.

It isn't acquiring angular momentum there as it is a radial force. On the other hand: It is acquiring angular momentum from the electric field. But that's a property of the particle motion which has nothing to do with its spin.