Heavy quark studies with nuclear emulsions
Emulsions have started particle physics with the discovery of natural radioactivity by Becquerel in 1896. The development of the ``nuclear emulsions'' made it possible to detect tracks of single particle and to perform detailed measurements of their interactions. The discovery of the pion in 1947 was the first, spectacular demonstration of their unique features for the direct observation of the production and decay of short-lived particles, with negligible or very low background. In particular, these features are now exploited for studies of heavy quark physics in experiments where nuclear emulsions are combined with electronic detectors and profit is taken of the remarkable technological progress in automated analysis. In these experiments, neutrinos provide a selective probe for specific quark flavors. Interesting results on charm production and decay are expected in the very near future.