Atomic energy as an humane endeavor: Retrospective on its development [report]

G.T. Seaborg, K.E. Stahlkopf
1989 unpublished
DISCLAIMER This report was prepared as an account of work sponsored by an agency of Ihc United States Government. Neither the United States Ciovcrnment nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal hanilin 11 responsi bility for the accuracy, completeness, or usefulness of any information, apparah; ' i.viuct, or process disclosed, or represents that its use would not infrince privately owned rit'htv Refer ence herein to any
more » ... fic commercial pntduct, process, or service by trade name, trademark, manufacturer, or otherwise docs not necessarily constitute or imply its endorsement, recom mendation, or favoring h> the United Stales (lovcrnmcm or any agency thereof The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States (iovcrnment or any agency thereof. Pre-fission and fission As a first year graduate student at Berkeley in 1934 nearly five years before the discovery of nuclear fission, I began to read the papers coming out of Italy and Germany describing the synthesis and identification of several elements thought to be transuranium elements. In their original work in 1934, E. Fermi, E. Amaldi, 0. O'Agostino, F. Rasetti and E. Segre bombarded uranium with neutrons and obtained a series of beta-particle-emitting radio activities. On the basis of the periodic table of that day (Figure 1 ) they were led to believe that the first transuranium element, with atomic number 93, should be chemically like rhenium (i.e., be eka-rhenium, Eka-Re), element 9* like osmium (Eka-Os) and so forth. Therefore they assigned a 13-minute activity to element 93. I quote from j classical paper written by Fermi [1], entitled "Possible Production of Ele-r"". -Atomic Number Higher than 92", which I remember reading at that ti •• "This negative evidence about the identity of the 13 min.-activity from a large number of heavy 'iements suggests the possibility that the atomic number of the element may be greater than 92. 'f it were an element 93, 1t would be chemically homologous with manganese and rhenium. This hypothesis is supported to some extent also by the observed fact that the 13 min.-activity is carried down by a precipitate of rhenium sulphide insoluble 1n hydrochloric acid. However, as several elements are easily precipitated in this form, this evidence cannot be considered as very strong." I recall reading soon thereafter a paper by Ida Noddack [2], entitled "Uber das Element 93," which took issue with this interpretation, suggesting that the radioactivities observed by Fermi et al. might be due to elements of medium atomic numbers: "Es ware denkbar, dass bei der Bexhiessung schwerer Kerne m1t Neutronen diese Kerne in mehrere grossere Bruchstucke zer'allen, die zwar Isotope bekannter Elemente, aber nicht Nachbarn der bestrahlten Elemente sind." [One could think that in the bombardment of heavy nuclei with neutrons these nuclei disintegrate into several larger fragments which, although they are Isotopes of known elements, are not neighbors of the irradiated elements.] However this paper, which intimated the possibility of the nuclear fission reaction, was not taken seriously. Experiments in Germany during the following years by 0. Hahn, L. Meitner and F. Strassmann (Figure 2 ) appeared to confirm the Italian interpretation and for several years the "transuranium elements" were the subject of much experimental work and discussion. In a typical paper by Hahn, Meitner and Strassmann [3], which I read, part of a series they published during 1935-1938, they reported a 16-minute ,jEka-Re*", 2.2-minute ,jEka"», 12-hour , 4 Eka-0s 21 ', 59-minute , 4 Eka-0s 33 *, 3-day "Eka-Ir"», 12-hour , 4 Eka-Pt"V In 1938 I. Curie and P. Savitch [4] found a product of 3.5 hours halflife that seemed to have the chemical properties of a rare earth, but they failed to give an interpretation of this astonishing discovery. Their paper, which I also read at the time, had the title, "Sur La Nature Ou Radioelement Oe Periode 3,5 Heures Forme Dans L'Uranium Irradie Par Les Neutrons," and included the following: •o Oi in a> A
doi:10.2172/6297183 fatcat:wm4fguwvwrgkfgu7asemfrnqta