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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 dont get angular momentum in a cyclotron?

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  • $\begingroup$ I think you are conflating two different forms of angular momentum here, that is the angular momentum due to the spin of the particle itself and the angular momentum it has traveling around the cyclotron. Also the particle always has angular momentum in it's path around the cyclotron, even on the straight segments, just compute $r \times F$ at any point on the straight segment. $\endgroup$
    – Triatticus
    Commented Jul 17, 2020 at 21:13
  • $\begingroup$ angular momentum does not come in different forms. a particle traveling in a circle has linear momentum (its translation through space) and angular momentum (its spinning). Just like the moon has an orbit as well as a rotation. $\endgroup$
    – aquagremlin
    Commented Jul 17, 2020 at 22:03
  • $\begingroup$ @aquagremlin the orbit of the moon defines also an angular momentum. The rotation about the moon's axis is has also angular momentum. hyperphysics.phy-astr.gsu.edu/hbase/amom.html .(Any origin in (x,y,z) as axis gives a value for angular momentum even if there is no crcular path $\endgroup$
    – anna v
    Commented Jul 18, 2020 at 3:33
  • $\begingroup$ @aquagremlin, yes angular momentum comes with two flavors, the spin angular momentum, S (moon rotating on it's axis.), and orbital angular momentum, L ( the revolution of the moon around the earth). The sum total angular momentum is then $\vec{J}=\vec{L}+\vec{S}$. $\endgroup$
    – Triatticus
    Commented Jul 18, 2020 at 5:24
  • $\begingroup$ OK . But really my question is about the availabiilty of experimental data regarding the behavior of the alpha particles coming out of a cyclotron and experiments aimed at measuring their angular momentum. $\endgroup$
    – aquagremlin
    Commented Jul 18, 2020 at 18:58

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