Irène Curie, daughter of Nobel-winning parents, earned doctorate on polonium alpha decay. Worked as battlefield radiographer in WWI, earning military medal. Married Frédéric Joliot, collaborated on atomic nuclei research from 1928. Identified positron and neutron in 1932 but credit went to others. Calculated neutron mass accurately in 1933. Transmuted boron to radioactive nitrogen, aluminum to phosphorus, magnesium to silicon in 1934. Created radioactive isotopes cheaply for medicine. Pioneered radium nuclei research aiding German nuclear fission discovery. Built France's first nuclear reactor Zoé in 1948 producing 5 kilowatts. Exposed to polonium explosion in 1946 causing fatal leukemia by 1956. Family holds record five Nobel Prizes. Children Hélène and Pierre became scientists. Joined communists, opposed fascism, supported Spanish Republicans. Hid nuclear fission documents from military use in 1939. Directed Institut Curie and CEA commissioner post-war.