Traces of electrons in a picture taken using the Wilson chamber

Traces of electrons emitted by silicon, previously irradiated by neutrons from Rn + Be in a picture taken by Irène Curie et Paul Savitch using a Wilson chamber. Silicon is situated in the lower part of picture. Fig. VII-B (between pp. 640-641), "Oeuvres scientifiques complètes de Frédéric et Irène Joliot-Curie (coll. ACJC)