The research included neutron resonance spectroscopy, the angular distribution of pion elastic and inelastic scattering on nuclei with optical model fitting.

He was named Pupin Professor of Physics in 1982. His ideas were later tested and confirmed by Bohr's and Mottelson's experiments. Rainwater also contributed to the scientific understanding of X-rays and participated in the United States Atomic Energy Commission and naval research projects.

Leo James Rainwater (December 9 1917 – May 31 1986) was an American physicist who shared the Nobel Prize for Physics in 1975 for his part in determining the asymmetrical shapes of certain atomic nuclei.