The neutrino (predicted)
Who
Wolfgang Pauli, Austrian physicist of Jewish descent (his paternal grandparents were Jewish; his father had converted to Catholicism).
When
1930
Where
Zurich, Switzerland
In 1930 Wolfgang Pauli proposed the existence of the neutrino, a tiny neutral particle, to explain missing energy in radioactive decay; it was detected experimentally in 1956. Pauli won the 1945 Nobel Prize for the exclusion principle. He came from a family of Jewish descent in Prague, though his father had converted to Catholicism.
Sources
Part of “The Gifts of the Jews” — verified Jewish contributions to the world, with sources.