Nobel prize to C. T. R. Wilson awarded in 1927 "for his method of making the paths of electrically charged particles visible by condensation of vapour''. Co-winner A. H. Compton "for his discovery of the effect named after him''
Wilson, C.T.R.; On an Expansion Apparatus for Making Visible the Tracks of Ionizing Particles in Gases and Some Results Obtained by Its Use
Proc. Roy. Soc. A87 (1912) 277;
Reprinted in Classical Scientific Papers. Physics. Facsimile reproductions of famous scientific papers. Mills and Boon Limited, London (1964) 355.
The WORLD of the ATOM, editors H. A. Boorse and L. Motz, Basic Books, Inc. Publishers, New York - London, v.I (1966) 679.
In a recent communication I described a method of making visible the tracks of ionizing particles through a moist gas by condensing water upon the ions immediately after their liberation. At that time I had only succeeded in obtaining photographs of the clouds condensed on the ions produced along the tracks of -particles and of the corpuscles set free by the passage of X rays through the gas. The interpretation of the photographs was complicated to a certain
extent by distortion arising from the position which the camera occupied. The expansion apparatus and the method of illuminating the clouds have both been improved in detail, and it has now been found possible to photograph the tracks of even the fastest -particles, the individual ions being rendered visible. In the photographs of the X ray clouds the drops in many of the tracks are also individually visible; the clouds found in the
ray tracks are generally too dense to be resolved into drops. The photographs are now free from distortion. The cloud chamber has been greatly increased in size; it is now wide enough to give ample room for the longest ray, and high enough to admit of a horizontal beam of X rays being sent through it without any risk of complications due to the proximity of the roof and floor.
Related references More (earlier) information appears in C. T. R. Wilson, Proc. Roy. Soc. A85 (1911) 285;
4He atom ion X
e atom ion X
atom ion X
Invention of the cloud chamber to visualize tracks of ionizing particles.