[en] For analyses of radiogenic argon-40 in rocks and minerals, using isotope dilution technique, a spike (³⁸Ar) implanted as ions in an aluminium foil target is proposed. The volume of the spike may be chosen in a range between 10^-7 and 10^-5 cm³ in accordance with the volume of argon-40 to be tested. The volume of ³⁶Ar contained in the targets is around 1.1x10^-4 of the ³⁸Ar volume

[en] A high capacity metal-glass argon extraction and purification system has been developed for K/Ar dating of geologic materials. A set of samples can be loaded simultaneously and degassed in turn in the system by high frequency induction heating in a molibdenum crucible. The argon purification is carried out by titanium sponge, molecular sieve, copper oxide and glass and charcoal filled traps cooled by liquid nitrogen. The ³⁸Ar spike and the atmospheric argon used for calibrating the mass spectrometer are dispensed by a gas-pipette system. 80-120 minutes after starting the degassing of the sample, the purified argon can be introduced into the mass spectrometer; the gettering materials regenerate in 1-5 hours, thus 1-3 samples may be analysed a day. The atmospheric argon inflow during an experimental process is less than 5x10^-8 cc STP. (author)

[en] The Lavras basin near Lavras da Mangabeira (Ceara, NE. Brazil) is a relatively small tectonic basin filled with non-metamorphic sediments resting on the Precambrian/Cambrian crystalline basement. K-Ar dating of six samples from an intercalated basaltic layer yields an age of 175 +- 4Ma, setting an age about the Early/Middle Jurassic boundary to the sedimentation. (Author)

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[en] The high-spin states formed in ³⁸Ar following the fusion of ¹⁴N, ¹⁶,¹⁸O, and ¹⁹F projectiles with targets of ²⁶Mg, ²⁷Al, and ²⁸Si have been investigated. Angular distribution, linear polarization, and γ-γ coincidence data on the γ rays emitted by these states were utilized to construct a decay scheme for ³⁸Ar, and to suggest probable spin-parity assignments for several new high-spin states. Results of lifetime measurements for several of these states are presented, and a comparison of the experimental level energies to the predictions of a simple weak-coupling calculation and a large-basis shell model calculation is given

[en] The construction of UHV metal-gas line is described. The instrumental set-up comprises the following units; (1) double vacuum crucible for Ar extraction, which is made of tantalum and can be heated by resistance oven to 1500 C; (2) ³⁸Ar isotope spike container with gas pipette for the isotope dilution technique; (3) two ovens - filled with CuO for oxidation of hydrogen and hydrocarbons and another filled with Ti shaving for cleaning all the reactive gases; (4) getter pump for final cleaning of argon and (5) 180 C-sector mass spectrometer for quantitative analysis of argon isotopes. (author). 11 refs, 8 refs

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[en] The structure of ³⁸Ar is investigated by the ³⁴S + α orthogonality condition model (OCM). It is shown that the observed energies and E2 transitions of the superdeformed band are well reproduced by the cluster model