At first sight, nothing could be simpler than nuclear emulsions, those thin strips of film designed to trap the tracks of passing charged entities—nuclei, protons, electrons and the other objects that inaugurated the field of particle physics. But the method's seeming simplicity hides a complex history. Scientifically, emulsions posed myriad problems and required years of effort by a dedicated corps of emulsion physicists and chemists, who had to learn how to make the film sensitive to minimally ionizing particles, and how to store, process, dry and ultimately analyze the ramified skein of tracks. Developed in the 1930s by Marietta Blau, an Austrian physicist who fled her homeland following the Anschluss in March 1938, the nuclear emulsion method was taken over by Cecil Powell, who transformed it during the 1940s into a cottage industry, with female “scanners” and an international team of physicists and chemists. From Powell's laboratory in Bristol, England, the method migrated to the burgeoning, industrial‐scale accelerator centers at Berkeley and Brookhaven, until even there, emulsions were displaced by the mammoth bubble chambers of the 1950s and 1960s.
Marietta Blau: Between Nazis and Nuclei
Peter L. Galison; Marietta Blau: Between Nazis and Nuclei. Physics Today 1 November 1997; 50 (11): 42–48. https://doi.org/10.1063/1.881996
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