|On consideration, I realized that this scattering backward must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greater part of the mass of the atom was concentrated in a minute nucleus||However, the actual results surprised Rutherford|
|Note that the image is not to scale; in reality the nucleus is vastly smaller than the electron shell||Under the prevailing plum pudding model, the alpha particles should all have been deflected by, at most, a few degrees; measuring the pattern of scattered particles was expected to provide information about the distribution of within the atom|
|According to Rutherford: It was quite the most incredible event that has ever happened to me in my life||They observed that a very small percentage of particles were deflected through angles much larger than 90 degrees|
|Rutherford's experiment consisted of a beam of , generated by the of , was directed normally onto a sheet of very thin foil in an evacuated chamber||A screen at the focus of a microscope was used as a detector; the screen and microscope could be swivelled around the foil to observe particles deflected at any given angle|
Although many of the alpha particles did pass through as expected, many others were deflected at small angles while others were reflected back to the alpha source.