Ernest Rutherford

The "father" of nuclear physics, Rutherford (1871-1937) pioneered the orbital theory of the atom notably in his discovery of rutherford scattering.

http://www.orcbs.msu.edu/radiation/radhistory/ernestrutherford.html

http://www.pbs.org/wgbh/aso/databank/entries/bpruth.html