Nuclear structure studies involving polarised iodine, samarium and europium : experimental techniques and theoretical models
Low Temperature Nuclear Orientation (LTNO) is an important technique in the study of nuclei far from stability. The theory of LTNO and its application to the measurement of static nuclear moments and other quantities of spectroscopic interest are reviewed. The off-line facility at Oxford was used to study the decay of 133I→133Xe and 135I→135Xe. 133I having Z=53 and N=80 has three protons above the closed shell Z=50 and two neutrons holes in N=82 shell, while 135I has fully closed neutron shell since it has N=82, and they are of considerable theoretical interest since a wide variety of the theoretical nuclear models may be used to describe the observed levels close to the stable double closed shell structure. Another aim is to search for the nuclear magnetic dipole moment of the ground state of 135I. Nuclear orientation of 133IFe and 135IFe enabled the mixing ratios of several transitions in the decay scheme of 133I and 135I to be determined. From temperature dependence for 135I, the nuclear magnetic moment of 135I has been deduced. Also temperature dependence for 133I, analysed using a simple model, gave value for the magnetic hyperfine field that differed from previous published values. The method of combining nuclear orientation with NMR has become a very popular technique in recent years for determining nuclear magnetic dipole moments very precisely. The purpose of the NMR/ON experiment was to measure the hyperfine field with greater precision and to get some idea of the proportion of nuclei subject to it. Light Eu and Sm nuclei have attracted attention as systems with the number of protons right below the Z=64 subshell gap and the number of neutrons approaching N=82 major shell closure. Odd-proton, odd-neutron and odd-odd nuclei near the A=140 region have been investigated in the framework of the particle-triaxial rotor model. Main attention has been paid to explanation of experimental magnetic dipole and electric quadrupole moments of ground and isomeric states. Model predictions for deformation parameters of 136-142Sm even-even cores have been extracted.