Nuclear emulsion readout techniques developed for the CHORUS experiment

The CHORUS experiment is pursuing the study of the production and decay of short lived particles from neutrino interactions in a nuclear emulsion target. The extraction of the full information from the emulsion sheets has been possible only thanks to the development of fully automatic microscopes. The technique of automatic scanning, pioneered in Nagoya, involves precision mechanics, high quality optics and a readout scheme allowing for fast decisions. Two complementary approaches, developed by the Nagoya and CERN groups of CHORUS, are based on the principle that all information from the emulsion sheets should be extracted at the highest possible rate, limited only by the camera readout and the mechanical stability of the microscope stage.