Why does one photon conserve spin in 22Na beta decay to 21Ne?

[huyen_vyvy]

I was looking at the beta decay process of 22Na and I have a question that really bugs me. 22Na spin +3 decays into 21Ne in the excited state with spin 2, and then this Ne nucleus will emit one photon and jumps down to the ground state with spin 0. if only one photon is emitted, isn't conservation of spin violated? or do we have to take into account orbital angular momentum as well?

 

[Meir Achuz]

The nuclear spin can change by 2 if the emitted radiation is quadrupole.
This usually as a longer lifetime than the usual dipole radiation.
You could think of the quadrupole radiation as a photon with orbital angular momentum.