Features and Properties
Nuclear Emulsion are like photografic ones, composed of AgBr in a main body of gel, with some differences, among these:
The aim is detecting tracks of ionizing particles, as sequences of developed grains along their trajectories inside the emulsion that will be observed using a microscope.
A ionizing particle passing through the emulsion gives its energy to the Ag grains. These can be developed becoming metallic Ag. When emulsions are fixed these grains are locked to the main body of the emulsions while the remnant part is washed away. So a track is left where the particle passed, usually of about a half micron diameter that can be observed as black grains by means of a microscopes.
- the ratio of AgBr in gel is about 10 times bigeer than the photografic emulsion;
- they are thicker (up to 2 mm rather than a few microns);
- Ag grains, when developed, are smaller.
Uses in Particles Physics
Their main use is detecting charged particles their interactions and decays in a direct way; or, indirectly, neutral particles through their interactions. Sometimes they are also used as an active target, that is as a detector and a target for particles beams at the same time.
Nuclear emulsions provide an impressive accuracy in spatial and angular measurements (fractions of microns and few milliradians) and perhaps that is the reason why, after 90 years, they are still used in nuclear experiments being so the oldest detector known and still used in nuclear and particle physics.
Links to Nuclear Emulsions Productors
Nuclear emulsions are produced by the same developers of the photografic emulsions. Among these Fuji, Ilford, Nikfpi and Kodak
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