РАСПРЕДЕЛЕНИЕ ЗВЕЗД, ОБУСЛОВЛЕННЫ Х КОСМИ ЧЕСКИМ ИЗЛУЧЕНИЕМ, В ЛДЕРНЫХ ЗМУЛЬСИЯХ

---

On the star distribution, caused by the cosmic rays in nuclear emulsions

     

ФОТОЯДЕРНЫЙ ЭФФЕКТ Н А НИКЕЛЕ, МЕДИ И ЦИНКЕ

, - 17,6 , . , (8±4)·10^–23, (7±4)·10^–23 (4±2)·10^{–23 2}. , - .     

A resistometric investigation of the decomposition kinetics of Al-21·8 at.% Zn solid solution at 276 °C

Under the condition of nearly equilibrium concentration of vacancies, time dependence of the amount of isothermal transformation given byy=R/R _f was investigated whereR _f is the total structural change of resistivity on completion of the whole process andR is the measured resistivity change. The investigation was done on the 21·8 at.% (40·3wt.%) Zn alloy under the condition of relatively low supersaturation of a few degrees centigrade below the metastable _R solvus line. The total transformation involves four kinetic stages: the first two stages correspond probably to diffusion-controlled growth of the _R particles from the supersaturated solid solution and to the ripening of these particles till their conversion to the cubic phase takes place. The last two kinetic stages account analogously for the particles growth and ripening. Both _R and phases were identified by the transmission electron microscopy. When separating the individual stages, the approximation byy=1–exp [–(mt) ⁿ] of the amount of transformationy was used. The approximation allowed to get the starting values of both the time and the change of the structural part of the electrical resistance for individual stages and also to derive the parametersm _i, n_i which had to be redetermined for the individual separated stages. These data made it possible to synthetize the experimental curves ofR andy vs. time for the total transformation.It is a pleasure to thank Doc. Dr. V.Syneek CSc. for stimulating the author's interest in this problem and for providing helpful discussions. I also would like to express my thanks to Ing. P.Bartuka CSc. for the transmission electron microscopic study carried out to identify the particular phases. The author is indebted to Ing.V. íma for the preparation of the investigated alloy and to Mrs. A.Mendlová and Mr. P.Vyhlídka for technical assistance.     

The structure of83Sr excited states

The -decay of⁸³Y isomers (7.06 min and 2.85 min) have been studied by means of Ge (Li) detectors. The proposed level scheme of the⁸³Sr nucleus is based on the coincidence measurement and the analysis of energy sums. The intensity balance requirement leads to _T (35·5 keV)=3.2 which is consistent with M1 multipolarity of this transition. A probable structure of some of the excited states in the⁸³Sr nucleus is discussed in the framework of Alaga's model and Kuriyama's model.     

Magnetic study of some liquids and gases adsorbed on polymers

The paper reports on the measurements of magnetic susceptibility of methylalcohol and toluene adsorbed on polypropylenes of two different molecular masses PP 5056, PP 5078, polyethylene-terephtalate and cellulose. The measurements were carried out for the full range of covering, possible at room temperature, and comparison with the additivity law was made in the whole range of concentrations. With the exception of methylalcohol in PP 5078, all samples showed noticeable deviations from linearity in the dependence of susceptibility on the percentual share of the adsorbate, the deviations were towards decreasing diamagnetism. Polyethyleneterephtalate with methylalcohol showed contradictory results. The measurements were completed with a magnetic study of adsorption of natural air and pure oxygen on cellulose and PP 5506.As far as the interpretation is concerned, the measurements of magnetic susceptibility are in good agreement with experiments on high resolution nuclear magnetic resonance (NMR). From the experimental results the authors draw up conclusions as to the character of mutual interaction of polymers with given adsorbates, to the location of an adsorbed molecule on the polymer surface, and to the contribution of Van Vleck polarization paramagnetism and other susceptibility components on the experimental results.Toluene C₆H₅.CH₃, adsorbed on polypropylene, showed two more peaks beside a NMR signal of C₆H₅; they were identified as the signals of CH₃ adsorbed on non-equivalent parts of a polypropylene macromolecule.     

160Tb nuclear orientation in yttrium single crystal

First experimental results of¹⁶⁰Tb nuclear orientation in yttrium single crystal matrix are described. The influence of external magnetic field in combination with the crystal field interaction is discussed.     

Magneto-optical effects in crystals at the normal incidence

We consider the interaction of a polarized electromagnetic wave in a magnetically ordered crystal plate surrounded by an isotropic ambient at the normal incidence. The crystalline medium of the plate is specified by the general non-symmetric permittivity tensor. The results are expressed in terms of the transmission and reflection matrices which relate the electric fields of the incident wave to those of transmitted and reflected waves. Their applications are illustrated by examples of an isotropic plate magnetized normal to the interface, a cubic crystal magnetized parallel to the interface and an orthorhombic crystal magnetized along the axis normal to the interface. The effect of the reflection from the interfaces and the interference effect are included. The paper treats the reflection at an interface between an isotropic ambient and an absorbing magnetic crystal at small non-zero angles of incidence. The general reflection matrix is applied to the determination of the magneto-optical effects quadratic in magnetization.     

Effect of water of crystallization on magnetic properties of MgSO4

The object of this paper has been to determine the effect of water of crystallization on magnetic properties of MgSO₄. Changes in the magnetic properties of MgSO₄ in depenedence on the number of waters of crystallization have been established from the magnetic susceptibility changes. The value obtained by measurement differs from that calculated by the additivity law. This disagreement can be explained by the presence of the thermally independent Van Vleck's polarization paramagnetism _p .The paper brings forward calculations of _p values for the individual hydrates of MgSO₄.i H₂O fori=0, 1, ..., 7. Besides, it examines what portion of the polarization paramagnetism _pi of the overall values of _pci is due to the effect of water of crystallization. On the basis of this information the deviation from the spherical symmetry, caused by hydration of the MgSO₄ molecule, has been interpreted.