Nuclear History archive — page 11

An open navy velvet medal case with two round recesses: one holds a gold medal with a laurel wreath, the other is empty and lit by a soft beam of light, with a green sprig beside it

Hahn's Fission Nobel and the Exclusion of Lise Meitner

Otto Hahn alone won the 1944 Nobel Prize in Chemistry for fission; Lise Meitner, nominated 49 times, was left out for reasons historians later traced to committee structure, wartime isolation and haste.

A wooden coat stand in a sunlit 1930s physics laboratory holding a single jacket that is half white lab coat and half olive military tunic with brass buttons

The Discovery of Fission

World War II Begins: Fission Research in Six Countries (1939–1940)

When war broke out on September 1, 1939, no country yet treated fission as a top-priority weapon, but German Army Ordnance, France's Ministry of Armament, a US uranium committee, a Soviet commission and Japan's RIKEN were all drawing the research toward the state.

A stack of thin translucent cigarette papers on a filter-paper disk dusted with pale yellow uranium oxide, beside a brass orrery holding a pale cyan planet and a deep blue planet

The Discovery of Fission

McMillan and Abelson Discover Neptunium (1940)

In spring 1940 at Berkeley, McMillan and Abelson showed that a 2.3-day activity grew from 23-minute uranium-239 and was element 93, submitting "Radioactive Element 93" on 27 May 1940.

A dented vintage aluminium canister lashed with rope to a wooden pallet on the deck of an old cargo ship at sunrise, with a hazy harbour behind

The Discovery of Fission

Smuggle the 26 Cans: Norway's Heavy Water, 1940

In March 1940 Jacques Allier took Norsk Hydro's 185 kg of heavy water to Paris; in June Halban and Kowarski shipped it from Bordeaux to Britain on the SS Broompark.

A vintage stack of thin metal plates coated in yellow uranium oxide on a wooden table in an empty marble-pillared metro hall, with one tiny spark between the plates

The Discovery of Fission

Splitting on Its Own: Spontaneous Fission, 1940

In 1940 Flerov and Petrzhak, working under Kurchatov, found spontaneous fission of uranium, ruled out cosmic rays in Moscow's Dinamo metro station and reported it in Physical Review 58, 89, while Zeldovich, Khariton and a new uranium commission laid the first Soviet groundwork.

A vintage brass electroscope with a round glass window beside a small porcelain dish of greenish uranium oxide powder and a cherry blossom petal

The Discovery of Fission

Nishina's Cyclotrons in Tokyo (1937–1940)

Yoshio Nishina's RIKEN laboratory started a cyclotron in April 1937, and in 1940 his team with chemist Kenjiro Kimura found uranium-237 and symmetric fission by fast neutrons, narrowly missing element 93.

A stack of old typed manuscript pages tied with red ribbon and sealed with a plain red wax seal, beside a fountain pen on a bright desk

The Discovery of Fission

Szilard's Campaign for Voluntary Secrecy (1939–1940)

In spring 1939 Leo Szilard urged physicists to hold back fission results; Joliot refused, but in 1940 a voluntary National Research Council committee led by Gregory Breit kept American fission papers out of print.

A chunk of dark pitchblende uranium ore resting on a blank file folder tied with red ribbon, beside a fountain pen and a teacup on a sunlit oak conference table

The Discovery of Fission

Germany's Uranium Club (1939)

In April 1939 an education-ministry meeting formed Germany's informal Uranium Club while two Hamburg chemists warned the army of a new explosive; after war began, Army Ordnance relaunched the group in September.

A curved glass vacuum tube between two steel magnet poles splits a beam into a wide silver arc and a thin amber arc that end in small brass collector cups, on a bright background

The Discovery of Fission

Bohr, Wheeler and Uranium-235 (1939)

In February 1939 Niels Bohr argued that rare U-235, not U-238, splits with slow neutrons; the Bohr–Wheeler theory published on 1 September 1939 explained why, and Nier and Dunning's separated samples confirmed it in March 1940.

A round glass flask of glowing yellow-green liquid on a white bench, with a thread of light inside branching from one point into two and then many

The Discovery of Fission

One Begets Two: Fission Neutrons, 1939

In spring 1939 Szilard and Zinn, Fermi's team and Joliot's Paris group found that each fission frees more than one neutron (Paris: 3.5 ± 0.7; today about 2.4), opening the road to a chain reaction.