When gamma radiation travels through the magnetic field of a cloud chamber or bubble chamber, in some cases the ray turns into an electron and an anti-electron. In the new system, we would say the gamma ray was split in half by the magnetic field of the chamber. The ray is composed of an electron alternating with an anti-electron and the magnetic field sends them in opposite directions because of their opposite charge. They spiral to a quick stop because they are half-waves, which have little penetrating power compared to full waves.
Fig. 8. Gamma radiation travelling through a magnetic field is split into
its two halves.
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