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971.
The features of positron annihilation in KCl crystals before and after radiation exposure is investigated. A significant increase in the efficiency of the ortho-vapor process of positronium state conversion is detected. A model is proposed for taking part in the ortho-vapor conversion of conduction electrons drawn into the conduction band by a positron field that affords a qualitative interpretation of the results obtained and permits values of the electron concentration in a spur to be obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 98–102, July, 1988. 相似文献
972.
G. S. Krinchik E. E. Chepurova B. K. Ponomarev O. P. Akhmatova A. P. Zhukov 《Russian Physics Journal》1988,31(3):250-255
The characteristics of the distribution of magnetization and remagnetization of microsections of the surface in the amorphous alloy Co70Fe5Si10B15, prepared in the form of thin ribbons, were studied by the magnetooptical method. It was found that the magnetization I on the surface of the amorphous ribbon studied was strongly nonuniform. It was established that heat treatment (HT) of the sample leads to the appearance of regions of reversed magnetization in the surface layer of the ribbon, while thermomagnetic annealing reduces the nonuniformity of I. The conservation of the transverse component in the HT sample in fields where the magnitude of the component of magnetization parallel to the length of the ribbon remains virtually unchanged suggested that a domain structure of the magnetization ripple type, owing to the strong microdispersion of the magnetic anisotropy, is realized in this sample.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 89–94, March, 1988. 相似文献
973.
V. P. Germogenov O. M. Ivleva Ya. I. Otman L. E. Épiktetova 《Russian Physics Journal》1988,31(1):73-77
Studies have been carried out on the perfection of then-AlxGa1–xSb1–yAsy (0.12x0.26) layer grown on GaSb substrates under different conditions of lattice matching. During the relaxation of the mechanical stresses at first a system of tilt dislocations with a density of up to 5 · 105 cm–2 is formed while in thick layers (h 20 m) a network of misfit dislocations parallel to the heteroboundary is formed. The time required to dissolve a weighed amount of GaAs in the melt is shown to be of major importance for obtaining layers of a solid solution that are isoperiodic with the substrate. The entry of arsenic only in the initial portion of the epitaxial layer can reduce the dislocation density in the layer without decreasing the measured value of Aa. Dissolution of a weighed amount of GaAs in a Ga + Sb melt for two hours at T=730–750°C is sufficient to obtain layers of AlxGa1–xSb1–yAsy solid solution that are isoperiodic with the substrate.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 84–89, January, 1988.In conclusion, we thank L. V. Druzhinina for useful discussions as well as Z. V. Korotchenko, L. S. Khludkova, and F. S. Kim for assistance in the performance of the experiments. 相似文献
974.
We consider the Weil elliptic curve E/ℚ and let
be its canonical L-series. Admitting the Birch-Swinnerton-Dyer conjecture and fixing the curve E, a criterion is given for
the finiteness of the group ED(ℚ) for twisted elliptic curves ED, defined by the condition
相似文献
975.
V. P. Gorokh 《Journal of Mathematical Sciences》1990,51(5):2509-2512
LetE
n, k
be a pseudoeuclidean space with linear elementdx
1
2
++dx
n–k
2
–dx
n–k
+1/2
––dx
n
2
. The area of a smooth two-dimensional surface inE
n, k
is defined by
, whereE, F, andG are the coefficients of the first fundamental form of the surface andD is the region of variation of the parametersu andv. The following theorem is proved: LetL be a piecewise smooth closed curve inE
n, k
(1kn–1). Then there exists a two-dimensional piecewise smooth surface of arbitrarily small area bounded by the curveL. 3 figures.Translated from Ukrainskií Geometricheskií Sbornik, No. 30, 1987, pp. 18–22. 相似文献
976.
We obtain partial results on the conjecture that for the almost Mathieu operator at irrational frequency, , the measure of the spectrum,S(, , )=|4–2|. For ||2 we show that if n is rational and
irrational, then
.Dedicated to Res Jost and Arthur WightmanResearch partially supported by U.S. NSF grant number DMS-8801918 and by BSF under grant number 88-00325 相似文献
977.
E. Bergshoeff M. P. Blencowe K. S. Stelle 《Communications in Mathematical Physics》1990,128(2):213-230
We show that there exists a one-parameter family of infinite-dimensional algebras that includes the bosonicd=3 Fradkin-Vasiliev higher-spin algebra and the non-Euclidean version of the algebra of area-preserving diffeomorphisms of the two-sphereS
2 as two distinct members. The non-Euclidean version of the area preserving algebra corresponds to the algebra of area-preserving diffeomorphisms of the hyperbolic spaceS
1,1, and can be rewritten as
. As an application of our results, we formulate a newd=2+1 massless higher-spin field theory as the gauge theory of the area-preserving diffeomorphisms ofS
1,1. 相似文献
978.
J. P. Leroy J. Micheli G. C. Rossi K. Yoshida 《Zeitschrift fur Physik C Particles and Fields》1990,48(4):653-661
In this paper we present a non-trivial check of the consistency of the quantization of a gauge theory with fermions (QCD) in the temporal gauge. We use the approach based on the finite time Feynman propagation kernel, in which the Gauss law is imposed as a constraint on the states by means of a functional integration over all the time independent gauge transformations acting on the boundary values of the fields. We spell out in detail the “Feynman rules” when fermions are present and we compute, as an example, the gauge invariant correlation function $$\begin{gathered} G(t) = \left\langle {\bar \psi (0,t)(\gamma _5 \gamma _0 )\frac{{1 - \gamma _0 }}{2}P} \right. \hfill \\ \left. { \cdot \exp \left( {ig\int\limits_0^t {A_0 (0,t')dt'} } \right)(\gamma _5 \gamma _0 )^ + (0,0)} \right\rangle \hfill \\ \end{gathered} $$ up to orderg 2, obtaining the expected result. 相似文献
979.
H. Fawcett S. Barlag H. Becker E. Belau T. Böhringer M. Bosman V. Castillo V. Chabaud D. Bucholz C. Damerell C. Daum G. De Rijk H. Dietl S. Gill A. Gillman R. Gilmore T. Gooch P. Gras Z. Hajduk E. Higon B. Hyams D. Kelsey J. Kemmer R. Klanner U. Kötz S. Kwan B. Lücking G. Lütjens G. Lutz J. Malos W. Männer E. Neugebauer H. Palka M. Pepé G. Polok J. Richardson M. Rozanska K. Rybicki H. Seebrunner U. Stierlin R. Tapper H. Tiecke M. Turala G. Waltermann S. Watts P. Weilhammer F. Wickens L. Wiggers A. Wylie T. Zeludziewicz ACCMOR Collaboration 《Zeitschrift fur Physik C Particles and Fields》1990,46(4):513-519
The production of the neutralK ? (892) resonances by 200 GeVK ? andπ ? has been studied over the kinematic range 0.0<x f<1.0 andp t 2 <5.0 GeV2. Longitudinal and transverse momentum distributions are presented. In addition the decay angular distributions inK ? fragmentation to \(\bar K^{0*} \) have been investigated. 相似文献
980.
Conclusion In a planar logarithmic spiral excited at its periphery there simultaneously exist surface, quasieffluent, and radiated waves; the phase velocities of surface and quasieffluent waves are identical and depend on the reduced radius k, which defines the regions of normal and anomalous dispersion; in the region kn the surface wave transforms to a radiated one by means of the quasieffluent; the directional pattern differs little from that for central excitation, with ellipticity coefficient of a spiral open at the center varying from 0.7 to 0.9 over a 1:2 frequency range; the input impedance depends weakly on the presence of reflection at the center of the spiral, is of an oscillating character, and changes more intensely than for central excitation.Khar'kov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 1, pp. 78–84, January, 1990. 相似文献
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