ФОТОЯДЕРНЫЙ ЭФФЕКТ Н А НИКЕЛЕ, МЕДИ И ЦИНКЕ

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

ВЛИЯНИЕ ПРЕДВАРИТЕЛ ЬНОГО ОСВЕЩЕНИЯ НА ПР ОВОДИМОСТЬ И ФОТОПРОВОДИМОСТЬ З АКИСИ МЕДИ

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The effect of preliminary illumination on conductivity and photoconductivity of cuprous oxide

     

Experimental investigation of superconductivity in 2H-NbSe2 single crystal

The basic quantities characterizing the superconducting behaviour of pure 2H-NbSe₂ single crystals have been determined from specific heat measurements, performed between 0.3 and 10 K in magnetic fields up to 55 KG. When Ti impurities are added, changes are observed both in the superconducting parameters and in the onset of charge density waves, strengthening the idea that a connection exists between the two phenomena.     

Canonical realizations of classical lie algebras

We construct sets of canonical realizations for all classical Lie algebras (A _n ,B _n ,C _n ,D _n ). These realizations depend ond parameters,d=1, 2, 3,...,n; all Casimir operators are realized by multiples of identity. For most of the real forms of these algebras we give sets of realizations which are, moreover, in well-defined sense skew-Hermitian. Further we study extremal cases of the presented realizations. The realizations with minimal numbers of canonical pairs are discussed from the point of view of general results concerning minimal realizations. On the other hand, a connection is found between our maximal realizations ofA _n and the Gel'fand-Kirillov Conjecture.The authors would like to thank Prof. A.Uhlmann for his kind interest in this work. They are very grateful to Prof. A. A.Kirillov and Prof. D. P.Zhelobenko for helpful discussions and to Prof. J.Dixmier for his informative letter concerning the problem mentioned in Sect. 5.One of the authors (W. L.) thanks Prof. I.Úlehla for the hospitality at the Nuclear Center of the Charles University, Praha.     

Inner-shell ionization ofZ=25–32 elements by 5-48 MeV32S ions

TheK-shell ionization cross sections of Mn, Ni, Cu, Zn and Ge under³²S bombardment have been measured in the energy range from 5 to 48 MeV. The cross sections are compared with available theories based on a direct Coulomb ionization mechanism and with the predictions of theK-vacancy sharing process. This last process can reasonably account for the measured cross sections at high bombarding energies. The energy shifts of theK - andK -lines and theK /K -intensity ratios have also been measured. This information is used to deduce the defect configuration of the atoms. The mechanisms responsible for the multiple vacancy production are discussed.     

Cross-sections for deuteron photo-disintegration from 139 to 832 MeV

The cross-sections for deuteron photo-disintegration have been measured at nine c.m. angles from 37 to 143 degrees. The minimum and maximum photon energies have been 139 and 832 MeV respectively. The results are in agreement with earlier data above 300 MeV, but are significantly larger below 200 MeV, the discrepancies being up to 50% at the lowest energies measured.     

Etude d'impulsions lumineuses breves par interferometrie a deux ondes

We have studied the evolution of the light transmitted through matter in which an optical breakdown is taking place. With a two-waves interferometer made a birefringent plate between polarizers we get informations about the time correlation function of the fields. With an interferometer made of two identical harmonic generating plates separated by a dispersion medium, we learn about the correlation function of the square of the fields. Both systems act as spectral filters with a notch cosine-shaped centered at the incident frequency. We have also observed a transient angular spreading of the beam not previously emphasized which brings a further complication in the picture.     

Explicit calculation of a tricritical point in a Pauli paramagnetically limited superconductor

We extend the Maki-Tsuneto Green's function formulation for the critical magnetic field vs temperature of a Pauli paramagnetically limited thin film superconductor to include the field conjugate to the order parameter and show the system displays a tricritical point. We present numerical calculations within the mean field theory in the neighborhood of the tricritical point and describe an explicit experimental arrangement for producing an adjustable staggered field.     

Search for anomalous interaction mean free paths of charge, 2≦Z≦18 projectile fragments in emulsions exposed to 1.8 A GeV40Ar ions

⁴⁰Ar-emulsion interactions are studied, to investigate the question of anomalons, in twoG- 5 emulsion stacks. In about 4600 primary interactions, projectile fragments of Z≧2 for all generations have been followed until they interact or leave the stack. After careful estimation of charges of these fragments, variation of their mean free paths is studied as a function of distance from the preceding interaction. Generation effect,N _h dependence and production angle effect are investigated. In addition multi-chain events are analysed separately. Our results do not show anomalons at the 6% level and are consistent with non-occurrence of anomalons. However, this experiment is not sensitive enough to rule out anomalons (with a mfp of the order of 2 to 3 cm) produced at about 1% (or less) level.