How could an alpha particle strike the phosphor screen on the same side of the foil as the alpha particle source

Temperature and pressure

Your question is not clear but if you can explain yourself i would be glad to .  just trying to : ))

The atomic nucleus made up from protons (yellow) and neutrons (blue) and held together by nuclear forces. nuclear forces (also known as nuclear interactions or strong forces) are the forces that act between two or more nucleons. they bind protons and neutrons (“nucleons”) into atomic