Word: boron
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...Joliot and Irene Curie-Joliot, son-in-law and daughter of the late Marie Sklodowska Curie. A vast and totally unforeseen field of research was opened last year when the Curie-Joliots discovered the phenomenon of artificial radioactivity. The young couple obtained a continued emission of positrons from boron, magnesium and aluminum by bombarding those elements with alpha particles (TIME, Feb. 12). Since then their results have been reproduced and extended in dozens of laboratories in a half-dozen countries, notably England, Italy, the U. S. Italy's Professor Enrico Fermi and his aids have coaxed radiations of beta...
Last January the Curie-Joliots of Paris pegged alpha particles (helium nuclei) into boron nuclei and got nitrogen. Similarly magnesium became silicon; alumi-num-phosphorus...
Unquestioned was the priority and importance of last week's announcement from the Rue Pierre-Curie. With alpha particles, which for more than a decade have been used to bombard vulnerable substances, the Curie-Joliots attacked boron. The expected neutrons hopped out instantly. But positrons (positive electrons) shot out also, and kept on shooting out after the bombardment stopped, as though the boron had been stimulated into a state of radioactivity. After 15 minutes the positrons were still darting out 30% as fast as at first: after 30 minutes 9% as fast; after 45 minutes 2.7%. Theoretically the radiation...
This, according to the researchers, is probably what happens: The attacking alpha particle joins a boron atom to form a neutron (which flies off) and an unstable nitrogen atom which in a few seconds or minutes changes to a carbon atom with the release of a positron. Hence, just as the spontaneous radioactivity of radium turns it finally into lead, the end-product of boron's artificial radioactivity is carbon. Not only boron but magnesium and aluminum became radioactive under similar treatment...
...Paris the Jean Frederic Joliots (daughter & son-in-law of Mme Marie Sklodowska Curie) projected alpha particles at lithium atoms. From each collision they recovered a boron atom and a neutron, which together weighed more than the original lithium atom and alpha particle. Dr. Kenneth Tompkins Bainbridge of the Bartol Research Foundation showed that the additional weight must have come from the energy which propelled the alpha particle at the lithium atom...