Radioactive-Ion Beams for the Fission Study of Heavy Neutron-Rich Nuclei

Physics of Atomic Nuclei - Quasi-elastic, multi-nucleon transfer reactions induced by the radioactive-ion beams with energy 4–6 MeV/u allow one to produce moderately excited neutron-rich...     

Magnetic and electric properties of the ternary alloys AB

The results of experimental studies of the electrophysical and magnetic properties of solid solutions based on the AB compounds with anion (Zn₃(P_xAs_1−x)₂ and cation (Zn_xCd_1−x)₃ P₂ substitution are reported. The Zn₃(As_xP_1−x)₂ solid solutions are characterized by p-type conductivity (∼ 10¹⁵  10¹⁷ cm⁻³), low Hall mobility and conductivity of ∼ 10⁻² — 10⁻³ ohm⁻¹ cm⁻¹. In the (Zn_xCd_1−x)₃P₂ solid solutions the samples rich in zinc are p-type, those rich in cadmium — n-type, the carrier concentration is ∼ 10¹⁶ — 10¹⁸ cm⁻³. From the measurements of the magnetic properties of the above mentioned alloys it is shown that in the investigated solid solutions a transition from the structure with direct optical transition to those with indirect optical transition occurs.     

Shifted identical bands: A new phenomenon

The levels in ¹⁶²Gd were identified in spontaneous fission studies. Its transition energies are remarkably similar to those in ¹⁶⁰Gd. From that work, an analysis of yrast bands in even-even proton to neutron-rich Ba to Pb nuclei led to the discovery of a new phenomenon, shifted identical bands (SIB). SIBs are yrast bands in neighboring nuclei (a, b) with moments of inertia which are identical when shifted by a constant amount κ, so J _1a (1+κ)=J _1b , from 2⁺ to 8⁺ and higher to 16⁺. Out of over 700 comparisons, 55 SIBs were found from stable to the most neutron-rich Ce-W nuclei with $\left| {\bar k} \right|$ between 1.5% and 13%, where the spread in κ is less than ±1%, and only four identical bands ( $\bar k \cong 0$ ). As examples, we found for ¹⁵⁸Sm-¹⁶⁰Gd, $\bar k = \left( { - 3.2_{ - 0.2}^{ + 0.1} } \right)\%$ (where the ± is the total spread in κ from ?3.1 to ?3.4); ¹⁵⁶Nd-¹⁶⁰Gd, (?10.6 _?0.2 ^+0.4 )%; ¹⁵⁸Sm-¹⁶⁰Sm, (3.4 _?0.3 ^+0.5 )%. The J ₁ values were fitted to a variable moment of inertia model with parameters J ₀ and C whose values correlate with the SIB J ₁ values. The SIBs are not correlated either with deformation or with the N _p N _n product of the IBA model.     

Collinear cluster tripartition channel in the reaction 235U(n th, f)

Investigation of the ²³⁵U(n _th, f) reaction using the miniFOBOS double-arm time-of-flight spectrometer of fission fragments confirmed manifestations of the earlier unknown many-body, at least ternary, decay involving almost collinear decay-product escape, which were first observed in the spontaneous fission of ²⁵²Cf(sf). The use of variables sensitive to the nuclear charge of fission fragments allowed the reliability of identification of decay events to be increased and new decay modes to be revealed.     

Composition of the phospholipids of seeds of Cercis siliquastrum

The phospholipids of the polar lipids of the seeds of the Judas tree and the fatty-acid composition of the N-acylphosphatidylethanolamines, the phosphatidylcholines, and the phosphatidylethanolamines, and also the molecular-species types of the fatty acids of the phosphatidylcholines and the phosphatidylethanolamines have been studied. It has been established that the seeds of the Judas tree contain ten phospholipids. The main fatty acids are palmitic and oleic.I. V. Kutateladze Institute of Pharmacochemistry, Georgian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 320–323, May–August, 1992.     

Acetylene adsorption on a clean iridium surface

The interaction of C₂H₂ with a polycrystalline iridium surface at 140 KT500 K has been studied by AES, XPS and UPS. A model of the bonding between C₂H₂ and Ir by the 1 orbitals of the hydrocarbon is proposed. The more pronounced energy splitting between the orbitals of acetylene during adsorption compared to that in the gas phase is ascribed to deformation of the acetylene molecule.

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C₂H₂ . 140 KT500 K AES, XPS UPS. C₂H₂ Ir 1- . - , , .