Decay of Samarium-153

Radiations emitted in the decay of Samarium-153 have been studied in the Siegbahn-Slatis beta-ray spectrometer. Using the internal conversion electron spectrum and the photo-electron spectrum with tin as radiator, the internal conversion coefficient αk has been determined for 102 Kev. and 70 Kev.gamma-rays. The relative intensities of the three beta-ray branches have been determined. A weak gamma-ray of energy 83 Kev. has been found and can be interpreted as a transition to the ground state from the first rotational level in Europium-153. The multipole order and character of the 102 Kev. transition is discussed

Formation and quenching of ortho-positronium in molecular materials

A correlation is observed between the lifetime and two-photon annihilation intensity by pick-off process of ortho-positronium in molecular materials. An empirical model, in terms of free volume, is developed to explain this correlation. The variation in lifetime and intensity with change of temperature and pressure, and due to melting of crystals, and glass-transition in polymers is considered, on the basis of this model

Longitudinal polarisation of beta particles from Rb<SUP>86</SUP>, Pr<SUP>144</SUP> and Co<SUP>60</SUP>

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Decay of Eu<SUP>155</SUP>

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Correlation between viscosity and positronium life-times for simple molecular liquids

The life-times of positrons inn-octane andn-hexadecane are measured at different temperatures. The viscosities and densities are shown to be correlated with the life-times on the basis of the free volume model. Similar data forn-alkanes and chemical isomers are interpreted in terms of this model

The lifetimes of positrons in oxides of arsenic and antimony

The lifetimes of positrons in crystalline powders of dimeric oxides of arsenic and antimony, and in trioxymethylene and polyoxymethylene are reported. In As4O6 and polyoxymethylene a longer component τ4 is observed in addition to the usually observedt 2 component. The variation of τ4 with temperature and pressure is studied in As4O6. On the basis of these results and the X-ray diffraction pictures, it is suggested that ortho-positronium atoms quenched in intercrystallite regions in As4O6 gives rise to τ4

Positron annihilation in annealed and quenched teflon and in sulphur

The value (τ2) and the intensity (I2) of the delayed component in the lifetime spectra of positrons annihilating in annealed and quenched teflon and in sulphur and crystex (polymer sulphur), at room temperature and at 77° K are reported. These data and the X-ray diffraction patterns for these materials are discussed in terms of the free volume model for the formation and quenching of positronium atoms in molecular materials

Origin of low-energy electron lines in the β-spectrum of <SUP>198</SUP>Au

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The physical state of chromium impurity in corundum

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