On January 6, 1939, experts learned of the first successful nuclear fission. The scientists Otto Hahn and Fritz Straßmann inform in the journal "Naturwissenschaft" about the irradiation of uranium with neutrons.
Attempts to split the atom were no longer new. In 1919, physicist Ernest Rutherford "smashed" the first atom, turning nitrogen into oxygen. He had gained another from one element. However, an oxygen atom is only slightly heavier than a nitrogen atom. In the years that followed, all the famous atomic laboratories converted atoms.
Power generation by means of atomic fission has long been hopeless
It was an established law that when atoms are bombarded, only those elements are formed that differ little in weight from the original element. Scientists thought it impossible for the atomic nucleus to split in the middle. That is why it was considered hopeless ever to be able to release the enormous energies that would have to occur when an atomic nucleus burst apart.
The first fission
Experienced experimental researchers, such as Enrico Fermi in Rome or Lise Meitner and Otto Hahn in Berlin, experimented on this basis for years in vain and constantly encountered new contradictions. In November 1938, Otto Hahn thought he knew the solution. In Copenhagen he met the famous physicist and Nobel Prize winner Niels Bohr and asked him what he thought about uranium becoming radium. Although radium is not much lighter than uranium, Bohr found the weight difference too great.
In 1925, Lise Meitner and Otto Hahn conducted experiments in the laboratory of the Kaiser Wilhelm Institute in Berlin.Hahn returned to Berlin and wanted to prove that his assumption was correct. In December 1938, Otto Hahn and his colleague Fritz Straßmann tried to obtain radium by bombarding uranium atoms at the Kaiser Wilhelm Institute for Chemistry in Berlin. They didn't succeed. But then the completely unexpected happened:While bombarding uranium with nuclear particles, they found the element barium, which is only half as heavy as uranium - so it must have been created by nuclear fission.
Lise Meitner interprets the events correctly
A few days later, Hahn wrote to his colleague at the Kaiser Wilhelm Institute, the physicist Lise Meitner, about the discovery. Meitner had had to leave Germany as a Jew a few months earlier. Together with her nephew Otto Robert Frisch, who was also a physicist, she was the first to give a physical interpretation of uranium fission.
At the beginning of 1939, Otto Hahn and his colleague Fritz Straßmann published the results of their experiments. The article "On the detection and behavior of the alkaline earth metals formed when uranium is irradiated with neutrons" appeared on January 6, 1939 in the journal "Naturwissenschaft". Otto Hahn was awarded the Nobel Prize in Chemistry in 1944 for his discovery.
Nuclear energy and nuclear weapons
Research into nuclear fission ushered in a new era - the age of atomic energy. The fascinating thing about nuclear fission back then was the prospect of being able to use the energy stored in the atomic nuclei. Natural radioactivity was not suitable for this. "In nuclear fission, on the other hand, it is possible to multiply the energy-yielding nuclear process in a chain reaction. Because each fission releases a few neutrons that can trigger further fissions," says the University of Mainz, for example.
The United States pushed the development of nuclear weapons massively.Internationally and especially in the USA, the discovery caused a tremendous stir. The first nuclear reactor went into operation in Chicago on December 2, 1942, realized under the supervision of the Italian physicist Enrico Fermi. It took just four years to translate the phenomenon into technology. The plant in Chicago was not used to generate electricity, but was part of the Manhattan Project, whose goal was the construction of nuclear weapons. The development and construction of the atomic bomb was pushed forward with enormous effort. During World War II, the USA used a nuclear weapon for the first time.
Civil reactor technology
The peaceful applications of atomic energy, for example in medical diagnostics, were mainly known and used after the war. With the nuclear reactor accident in Chernobyl in April 1986, civil reactor technology also fell into twilight. A discussion about the safety of nuclear power plants that has continued to this day began.
Radioactivity and nuclear fission
Radioactivity is omnipresent, for example in the form of cosmic radiation. On high mountains, the air is thinner and radioactive radiation from the cosmos is less well shielded. However, radioactive radiation also comes from the ground, for example from volcanic rock.
The term radioactivity describes the property of certain substances to convert without external influence and thereby emit a characteristic radiation. Atoms are often not stable. They decay spontaneously and emit ionizing, i.e. radioactive, radiation. However, the disintegration of atoms can also be forced artificially by supplying a suitable excitation energy. When irradiated with neutrons, the atomic nucleus is split into two or more significantly lighter atomic nuclei.
This splitting releases kinetic energy and intense radiation. In addition, two to three neutrons are produced, which can be used to hit and split other atomic nuclei. This creates an avalanche-like decay process. Nuclear fission can be used to generate energy, but it can also be used in nuclear weapons.