Incoming links: Ionization of air by radiation
This can be used to detect the ionization of air by radiation , see e.g. youtu.be/CZ7DoLLwW04?t=76 from Video "Ions produced by radiation carry a current by Institute of Physics".
Like all big names in science, she was at the right place at the right time and with the right interest and passion.
Notably, the man she married, Pierre Curie, happened to be a the world master at precisely the technique that she needed to carefully measure radioactivity: he had the most precise electrometers in the world, which allowed to detect small amounts of radioactivity via the ionization of air by radiation . These used piezoelectricity, which Pierre Curie co-discovered with his brother.
Marie Curie section of The Mystery of Matter episode 2
. Source. Fantastic illustration of Marie's life and work!- youtu.be/wbuDmY5gpXQ?t=2041 she specifically avoided X-ray research because she felt that there was too much competition in that area. TODO find a written reference about that and add it to Wikipedia.
Marie Curie c. 1920
. Source. 