The excited states of Gd 154 obtained from the decay of Eu 154 have been investigated. Precise measurements of the energies and intensities of the gamma transitions have been made, using Lithium-drifted Germanium detectors. A revised decay scheme is presented in which all the gamma transitional energies agree with the corresponding energy differences between levels to within 1 Kev. A 1263.3 Kev level is established by the presence of a gamma transition of 892.7 Kev. Two other gamma transitions of energies, 903.6 Kev and 582.1 Kev from the negative-parity levels to the 2⁺ beta excited level have also been discovered. The proper locations of the 995.9 Kev and 1004.5 Kev in the decay scheme are confirmed by a gamma-gamma coincidence method using a Germanium detector and a NaI(Tl) scintillator. The energies and intensities of the internal conversion electrons and the beta transitions have been measured by an intermediate image spectrometer. Their values are quite consistent with the established decay scheme. Theoretical values of the energy levels and the branching ratios for gamma transitions have been calculated, using the Asymmetric Rotator Model (J.P. Davidson's treatment). The 'stiffness' parameter of the nucleus µ and its asymmetry parameter γ obtained are 0.402 and 11.52 degrees respectively. Comparison of the experimental and theoretical energies of seven positive-parity levels gives a root-mean-square deviation of 1.5 %. Three out of the four experimental branching ratios are in good agreement with the theoretical values. The monopole transition probability for the transition from the 0⁺ beta excited state to the 0⁺ ground state measured also agrees with the present theoretical calculation. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This work proposes the development of a technique to growth of single crystals through metallic flux technique at the Sergipe State. Besides, the system YxGd1-xIn3 (0 x 0.5 to pass of 0.10 % ) has been obtained via this technique and its structural and magnetic properties are studied. X-ray diffraction results have been performed in order to verify if the desired crystalline phase was obtained. The experimental results show that it has been grown with success. The magnetic characterization is carried out through magnetic susceptibility data as function of temperature (2 x 300 K) and magnetic field (??7 H 7T). The T-dependence of the magnetization shows a suppression of the magnetic ordering temperature with increasing of the yttrium concentration. The analyses of these experimental data show that the system presents magnetic frustration which is linked to the dilution effect introduced by the yttrium ion in the gadolinium site. The magnetization data as function of magnetic field carried out at 2 K show a usual behavior of a material with antiferromagnetic ordering. / Este trabalho propôs a implementação da técnica de crescimento de monocristais via fluxo metálico, na Universidade Federal de Sergipe (UFS) campus de itabaiana. Além disso, o sistema YxGd1-xIn3 (0 < x < 0.5 a passo de 0.10 % ) foi obtido através dessa técnica e as propriedades estruturais e magnéticas foram estudadas. Medidas de difração de raios X foram realizadas com o intuito de verificar o crescimento da fase cristalina desejada. Os dados mostraram que ela foi obtida com sucesso. A caracterização magnética foi feita através de medidas de susceptibilidades magnética em função da temperatura (2 < x < 300 K) e do campo magnético (-7 < H < 7T). As medidas de magnetização em função da temperatura mostraram uma supressão da temperatura de ordenamento magnético com o aumento da concentração de ítrio. As análises desses dados mostraram que o sistema apresenta frustração magnética que está ligado ao efeito de diluição introduzido pelo íon de ítrio no sitio do gadolínio. As medidas de magnetização em função do campo magnético realizadas a 2 K mostraram um comportamento típico de um material com ordenamento antiferromagnético.