While many scientists contributed to the discovery and understanding of nuclear fission, the credit for the first experimental demonstration of nuclear fission is generally given to Otto Hahn and Fritz Strassmann, who in 1938 bombarded uranium atoms with neutrons and observed the creation of barium.

However, this discovery was interpreted and explained by Lise Meitner and Otto Robert Frisch, who recognized that the uranium atom had split into two lighter nuclei, releasing a tremendous amount of energy.

Here's a breakdown of the contributions:

* Otto Hahn and Fritz Strassmann: Conducted the experiment and observed the production of barium, demonstrating the splitting of uranium.

* Lise Meitner and Otto Robert Frisch: Explained the observed phenomenon as nuclear fission, providing the theoretical framework.

Therefore, while Hahn and Strassmann made the initial discovery, it was the interpretation of Meitner and Frisch that truly revealed the significance of the phenomenon and paved the way for its further development and application.