Desintegration stars


Marietta Blau est pionnière dans l’application des méthodes photographiques pour révéler les processus nucléaires à l’œuvre. En 1937, elle découvre des « étoiles de désintégration » — des traces de désintégrations nucléaires massives — dans les émulsions photographiques qu’elle expose pendant cinq mois sur le mont Hafelekar en Autriche. Elle observe ainsi la première trace d’une réaction nucléaire provoquée par les rayons cosmiques.

Marietta Blau (1894–1970) was an Austrian physicist who pioneered the development of photographic methods for imaging nuclear processes in the 1920s and 1930s. Her most dramatic discovery took place in 1937, when she and her associate Hertha Wambacher found ‘‘disintegration stars’’ – the tracks of massive nuclear disintegrations – in photographic emulsions that they had exposed to cosmic radiation. By showing that emulsions were capable of reliably recording highenergy nuclear events, the discovery launched the field of particle physics, but Blau herself was unable to participate in its development. Forced to emigrate in 1938, she spent years at the scientific margins, her contributions suppressed by her former colleagues in Vienna and, over time, severely underrecognized by the wider scientific community, including the Nobel physics establishment. At the time of her death in 1970 Blau and her work had been almost entirely obscured.

* Ruth Lewin Sime, the author of Lise Meitner: A Life in Physics, is currently writing a
biographical study of Otto Hahn.
Phys. Perspect. 15 (2013) 3–32
2012 Springer Basel AG
DOI 10.1007/s00016-012-0097-6 Physics in Perspective

Image : The cosmic-ray research station on the Hafelekar in 1931. Credit: Courtesy of the Zentralbibliothek fü r Physik in Wien.



Tracks left by high-speed protons on a sheet of photographic film are shown at left. The dotted horizontal lines were made by protons. The “star” was made when an atom disintegrated in the photographic emulsion. (Brookhaven Lab photo)