Excitation function bismuth

Numerous nuclear reactions have been employed to produce astatine. Three of these are particularly suited for routine preparation of the relatively long-lived isotopes with mass numbers 209, 210, and 211. The most frequently used is the ° Bi(a,xn) At (a = 1-4) reaction, in which bismuth 44, 74,120) or bismuth oxide (7,125) is bombarded by 21-to 40-MeV a-particles. The ° Bi(He, xn) At reaction can also be used to produce isotopes of astatine 152), the nuclear excitation functions (62) favor a predominant yield of ° At and °At. The routine preparation of astatine is most conveniently carried out through the ° Bi(a,xn) At nuclear reactions, from which a limited spectrum of astatine nuclides may be derived. The excitation functions for these nuclear reactions have been studied extensively (78, 89, 120). The... 

Further comments on the size and extent of this bismuth cross-section calculational effort should be made. Table 5 summarizes the number of target states that we will need to consider (the 21 states include both ground and isomeric states), the number of separate reaction excitation functions that must be included, as well as estimates of the number of computer runs and the CDC 7600 CPU computer time that will be required. In our calculations, we typically use energy-bin sizes of 10 to 250 keV, depending on the reaction type and the energy ranges of concern. 

Since the first reports from Australia and the observations in France (26 ) encephalopathy has been irrefutably shown to be a complication, not only of bismuth subgallate but also of other bismuth salts such as the subnitrate, carbonate and silicate. More than a hundred cases of bismuth encephalopathy have now been reported. The prodromal stage of bismuth encephalopathy is characterized by headache, insomnia, impairment of mental functions, asthenia and confu-sional states. After some time an overt encephalopathy develops abruptly, generally characterized by (1) psychosis, often with excitation and hostility, and finally coma, (2) myoclonic jerks, progressing to myoclonic crises, (3) ataxia and dysarthria, and (4) convulsions if generalized, these states are often resistant to anticonvulsant drugs. 

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