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Yields and isomeric ratio of xenon and krypton isotopes from thermal neutron fission of U 235

1981; American Institute of Physics; Volume: 24; Issue: 2 Linguagem: Inglês

10.1103/physrevc.24.523

1538-4497

Shawn S. H. Hsu, J.-T. Lin, Chio-Min Yang, Yikang Yu,

Nuclear reactor physics and engineering

The experimental cumulative yields of $^{85}\mathrm{Kr}^{m}$, $^{87}\mathrm{Kr}$, $^{88}\mathrm{Kr}$, $^{133}\mathrm{Xe}^{g}$, $^{135}\mathrm{Xe}^{m}$, and $^{135}\mathrm{Xe}^{g}$ and the independent isomeric yield of $^{133}\mathrm{Xe}^{m}$ in the thermal neutron fission of $^{235}\mathrm{U}$ have been measured by the gas chromatographic method. The independent yields of $^{133}\mathrm{Xe}^{g}$, $^{135}\mathrm{Xe}^{m}$, and $^{135}\mathrm{Xe}^{g}$ were deduced with the aid of $^{133}\mathrm{I}$ and $^{135}\mathrm{I}$ data. The isomeric yield ratios of $^{133}\mathrm{Xe}$ and $^{135}\mathrm{Xe}$ have been computed and compared with theoretical values since they have the same high spin state $J=\frac{11}{{2}^{\ensuremath{-}}}$ and low spin ground state $J=\frac{3}{{2}^{+}}$. The influence of the shell effect on the fission isomeric yield ratio is discussed. From the measured independent yield of Xe isotopes plus the reported data, the Xe-isotopic distribution curve has been constructed. The curve is compared with the isotopic distribution curves of Xe isotopes formed in 11.5 GeV proton interactions with $^{238}\mathrm{U}$ and Cs isotopes formed in 24 GeV proton interactions with $^{238}\mathrm{U}$. Upon fitting the yield curves we find that only those products with $\frac{N}{Z}\ensuremath{\ge}1.48$ fit a curve typical of a binary fission process.[NUCLEAR REACTIONS $^{235}\mathrm{U}$ (thermal neutron fission) $^{85}\mathrm{Kr}^{m}$, $^{87}\mathrm{Kr}$, $^{88}\mathrm{Kr}$, $^{133}\mathrm{Xe}^{g}$, $^{135}\mathrm{Xe}^{m}$, and $^{135}\mathrm{Xe}^{g}$ cumulative yields, $^{133}\mathrm{Xe}^{m}$, $^{135}\mathrm{Xe}^{g}$, $^{135}\mathrm{Xe}^{m}$, and $^{135}\mathrm{Xe}^{g}$ independent yields and isomeric ratio.]