Experiments on Chemical Concentration of a New Spontaneously Fissioning Nuclide from the Allende Meteorite

摘要

It is noted that the average number of prompt fission neutrons nu in the recorded events was between 4 and 10 for the Allende meteorite, whereas in the spontaneous fission of uranium this number is 2. Assuming that the new emitter is a superheavy element, an attempt was made to isolate it, together with the known volatile elements, from several kilograms of the meteorite. The carbonaceous Allende chondrite (type C3) is the largest meteortie of this class. The total weight of all the samples collected after its fall in Mexico in February 1969 was over 2000 kilograms. The method of separation is based on the relative ease with which the elements 112-118 can be volatilized in a hydrogen atmosphere. There is reason to believe that all these elements are more volatile than thallium. Some of them (including the lighter transactinide elements) can be sublimated in an oxygen atmosphere. All known elements undergoing spontaneous fission, as well as the principal constituents of the meteorite (34% SiO sub 2 , 25% MgO, 27% FeO, 3% Al sub 2 O sub 3 , and 3% CaO), have a very low volatility under these conditions. It is concluded that a new spontaneously fissioning emitter was isolated because of its volatility in a hydrogen or oxygen stream. It has been assumed that the superheavy elements possess these properties. It cannot be ruled out a priori, however, that this is an isotope of a known volatile element with an unusual nuclear structure. (ERA citation 04:037218)