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The decay properties of the neutron deficient nuclei $ sp{144}$Gd, $ sp{142}$Gd, $ sp{ rm 141g}$Gd, $ sp{ rm 141m}$Gd and $ sp{140}$Gd are investigated in detail for the first time and the new beta decaying isomers $ sp{ rm 141g,m}$Gd, $ sp{141}$Tb(A) and $ sp{140}$Gd are discovered. A gas-jet recoil-transport system and a conversion electron spectrometer are designed and constructed in order to measure the electromagnetic transitions emitted following their decay. Levels schemes are deduced for the daughter nuclei $ sp{144}$Eu, $ sp{142}$Eu, $ sp{141}$Eu, $ sp{140}$Eu, and $ sp{141}$Gd and spin-parity assignments are established for several states. The decay half-life of these nuclei is also measured. / The deduced information is discussed in the general context of the Z $ geq$ 50, N $ leq$ 82 mass region. The low lying structure of the N = 76, 77, 78, 79, 81 and 82 isotones is compared to the predictions of theoretical calculations using either spherical BCS or deformed Hartree-Fock plus BCS formalism with a semi-realistic interaction derived from the Tabakin potential. Contributions to original knowledge are outlined in Chapter V.

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Isotope shifts of twenty-two isotopes of strontium, $ sp{78}$Sr to $ sp{100}$Sr excluding $ sp{99}$Sr, and three isomers of strontium, $ sp{83 rm m,85m,87m}$Sr, have been measured using laser spectroscopy. The nuclear spins, magnetic and quadrupole moments, have been extracted from the data for all odd isotopes. The changes in mean square charge radii have also been evaluated for all isotopes and isomers. / The changes in mean square charge radii, which are compared to the predictions of the droplet model and Hartree-Fock plus B.C.S. calculations, show a pronounced shell effect at the closed neutron shell at N = 50 and a sharp increase at N = 60. The theoretical analysis suggests that the change in mean square charge radii for N = 60, 62 is due to the onset of a large static deformation. For the remaining isotopes, the changes are attributed to a change in size, a change in the predominantly dynamic deformation, and a change in the diffuseness of the nuclear charge distribution.

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The partition of radionuclides between solid and solution phase has been studied in humic/quartz sand ternary systems. Data have been recorded under ambient (air) and inert (O2 and CO2 free) atmospheres. For Eu (III) and Th (IV), the systems show simple ternary behaviour, with sorption decreasing (and mobility increasing) in the presence of humic, whilst for U (VI), the behaviour is more complex, with the humic enhancing sorption and reducing mobility. There is also evidence that the sorbed humic has an enhanced affinity for the uranyl, which is probably due to fractionation of the humic. Further, the behaviour of plutonium has also been studied in these systems. Pu (IV) showed the simple ternary characteristics, which had been observed for Eu (III) and Th (IV). Pu (V) and Pu (VI) systems exhibited more complex behaviour, with low concentrations of humic actually enhancing sorption, probably due to ternary complex formation. A simple mathematical model has been developed to predict the behaviour of both metal ion and humic acid. The model performs well in predicting the partition of the humic and that of the metal ions in the systems that show simpler ternary behaviour.

<p> Part I describes experiments carried out to search for possible products of ternary fission of 235U. Inert gases extracted from neutron-irradiated 235u were analyzed mass-spectrometrically for the presence of stable and radioactive neon and argon isotopes. No evidence for fission product neon or argon was found. Upper limits obtained for the yields are orders of magnitude lower than those suggested by some other studies.</p> <p> Part II describes measurements of relative yields and energy distributions of 3H, 3He, and 4He produced in fission of 235U. A short-range (<8 Mev) component in 4He, not previously established, has been detected in this work. The upper limit obtained for direct formation of 3He is lower by two to four orders of magnitude than the frequency of formation of 3He found in studies of other fissile nuclides.</p> / Thesis / Doctor of Philosophy (PhD)