Abstract
“Nuclear Transformations in the new High Energy Ranges” is the title of an address delivered by Prof. Glenn T. Seaborg, of the University of California, at a meeting of the American Chemical Society in New York on September 15 (see Chemical and Engineering News, 25, 2819; 1947). The great progress made recently in constructing new powerful machines for the acceleration of charged particles affords the possibility of bombarding targets with electrons of 100 MeV., and with deuterons end helium ions of 200 and 400 MeV. respectively. Entirely new nuclear reactions have been observed; for example, 7533As, bombarded with 400 MeV. helium ions, produces among other atomic species the well-known 3817C1. This means that the arsenic atom has lost no less than 16 protons and 21 neutrons, not counting the two protons and two neutrons shot into it at the start of the reaction. To distinguish such transmutations from the ordinary nuclear reactions in which only one or two particles are ejected, and from fissioh reactions in which the nucleus is broken into two fragments, the term ‘splintering reaction’ is proposed. Further, under such strong bombardment fission can be enforced in such elements as bismuth, lead and thallium, and even in an element so low in the periodic table as tantalum; but as the secondary particles emitted have a much smaller energy, there is no possibility of inducing a chain reaction such as in uranium. Many radioactive isotopes so far unknown have been found as a result of these new nuclear reactions, which have still further widened the field radiochemists are called upon to expldre; the splintering often leads to neutron-deficient isotopes and increases therefore in a welcome manner the comparatively small number of positron emitters among the artificial radio-elements. Some of them may find application as tracers. Still more important may be the physical aspects of this extension of the energy range; the creation from energy of mesotrons and, if the region of billions of electron-volts can be reached, also of neutrons and protons, seems now a possibility.
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New Nuclear Reactions. Nature 160, 897 (1947). https://doi.org/10.1038/160897d0
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DOI: https://doi.org/10.1038/160897d0