ON p. 251 of this issue of NATURE, an account is given of recent investigations by Prof. O. Hahn, Prof. L. Meitner and F. Strassmann on the bombardment of uranium by neutrons. Prof. Meitner and Dr.

ON bombarding uranium with neutrons, Fermi and collaborators 1 found that at least four radioactive substances were produced, to two of which atomic numbers larger than 92 were ascribed.

All types of radiation become less intense as they travel further away from the radioactive material. This is because the particles or rays become more spread out. The thicker the substance ...

^{4}\textrm{He}\) When a radioactive atom emits an alpha particle the mass number decreases by four and the atomic number drops by two. Here is the equation for the alpha decay of radon-219 into ...

Learn more here. In 1942, the Manhattan Project needed to create a chain reaction—a crucial step toward proving that it would be possible to make an atomic bomb. The scientists achieved this sustained ...