Neutrino Oscillations in Emulsion Experiment

Abstract

Emulsion experiments have a long history. Becquerel discovered radioactivity of uranium in 1896 following the discovery of Roentgen Rays [1]. He observed some activity of Uranium on a photographic emulsion penetrating through several sheets of black papers. Kinoshita then showed in 1910 [2] that α-particles produce a blackening of photographic emulsion so that individual α-tracks could be recognized. An attempt to improve the sensitivity of emulsions by doubling the concentration of AgBr was made by Bloch (Ilford, Ltd.) and Powell, in 1939 [3]. This effort was eventually rewarded by the discovery of “two mesons” in 1947. The first electron-sensitive emulsion (Kodak NT4) was produced by Berriman (1949) [4]. The improvement was made not only in the sensitivity of the emulsion, but also in the increased thickness. An emulsion up to 2 mm thick was successfully processed. We note a number of important discoveries made for new particle physics in cosmic rays in the 1940–1950’s using emulsions [5].