Atoms have two orthogonal spins, one due to the electrons \(B\) orbit and the other due to the protons in \(B\) orbit.
Silver atoms emitted from a source will have spins in all orientations. Their subsequent deflection by a magnetic field will create a circular pattern. Since the velocity of the particles in orbit is non zero, the circular pattern will be empty at the center. An un-deflected silver atom corresponds to one without magnetic moment and so without orbiting charged particles; which is not the case here.
Depending on the spread of the spin velocities under high heat, the pattern is a circular band of defined thickness.
In the original Stern-Gerlach experiment, the hole in the middle of pattern obtained is due to the non-zero velocities of the particles in orbit. The deflection obtained suggests that the atoms as a whole have magnetic moments.
If there is a E field that restrict deflection horizontally then, one cannot conclude that the deflection is only vertical, and that there is a directional bias in the magnetic moment of the atom nor that orbiting electrons have intrinsic binary spins. If the slit that admits the particles into the B field region is horizontal, then any observed directional bias is in part due to this slit.
Still, electrons from ionization of silver atoms are in the beam. The observed pattern is the result of the deflection of both electrons and silver atoms.
The applied E field draws a line of charged particles across the pattern horizontally and the deflections due to the B field splits the line in the middle. Without the E field, the pattern is more circular with a hole at the center due to deflections by the B field.
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