Recent experiments in novel nuclear excitations at the BNL AGS

Recent experimental work at the AGS dealing with unusual nuclear excitations is summarized. Three examples are given: the deexcitation of A hypernuclei by transitions, the production of A hypernuclei by the (⁺, K⁺) reaction, and the search for -nuclear excitations. The status of each field and the implications of the research for nuclear theory are discussed.Invited talk to the symposium Mesons and Light Nuclei IV, Bechyn, Czechoslovakia, September 5–10, 1988.     

A contribution to direct processes in the Co59(p,n) reaction forE p ∼ 6·5 MeV

Nuclear emulsions were used to study the energy spectrum and forward-backward asymmetry of neutrons from the Co⁵⁹(p,n) reaction forE _p 6·5 MeV. It was found that the decay of the compound nucleus makes a maximum contribution of 50% to the reaction yield. Energies of some excited states of the Ni⁵⁹ nucleus were also determined.

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Co⁵⁹(p,n) E _p 6,5 MeV

- Co⁵⁹(p,n) E _p 6,5 MeV. , 50%. , Ni⁵⁹.

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The authors would like to thank all those who helped in this work, particularly all members of the cyclotron group of the Nuclear Research Institute of the Czechoslovak Academy of Sciences, who so willingly helped with the irradiation, and H. Koutová from the Faculty of Technical and Nuclear Physics, who carefully measured the emulsions. Our thanks are also due to R. Krejová from the Faculty of Technical and Nuclear Physics for developing the emulsions and J. Kopecký from the Nuclear Research Institute for providing the cobalt target.     

The Gelfand-Levitan equation and its application to the scattering of neutrons on protons

The Gelfand-Levitan equation for the kernelP(r, r) (withrr) is formulated and then applied for determining the scattering potential in the scattering of slow neutrons on protons (for the case when the dependence of the nuclear forces on the spins can be neglected and onlys-scattering need be considered). The potentials obtained are the same as the Bargmann ones, found by a different method.

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- P(r, r) ( rr). , ( s- ). , .

     

Renormalization group equations with several length scales and crossover scaling functions for axial anisotropy

The critical behaviour of axially anisotropicn-vector models is characterized by two distinct length scales, the correlation lengths and for the easy and hard axes. In order to handle the full range of anisotropics from to partial differential renormalization group equations are derived, depending on and . The anisotropicX-Y model is studied in detail near four dimensions. The crossover scaling functions for the susceptibilities are calculated to first order in=4–d. Two distinct crossover regions are found for weak and dominant anisotropy, respectively.     

On ruelle's ξ-function for exponentially decreasing potentials

We show that Ruelle's generalised -function for a classical one-dimensional lattice spin system with two-body interaction (i) exp(-i )a(i) with >1 extends to a meromorphic function in the whole complex plane.     

A note on the Watanabe theory of weak interactions

It is shown that according to the Watanabe theory of weak interactions a resonant scattering of electrons by protons must take place. The resonant energy depends on the massm _B of the intermediate boson. Form _B=2300m _e this energy is about 213 MeV in the centre of the mass system (c. m. s.). The energy width at resonance is 1·4 MeV.

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, . , , . _{m B}=2300_{m B} , 213 MeV -. 1,4 MeV.

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The author would like to thank Professor V. Votruba for suggesting this note and for valuable advice and help during the work.     

Single crystal diffraction patterns of germanium. Part II

The rocking curves of Ge (111), (220), (333) for CuK ₁ radiation were measured by means of the triple-crystal diffractometer. Perfect silicon single crystals, cut parallel to the (111) plane were used in the monochromator part of the triple-crystal diffractometer. The results prove the suitability of such a monochromator for studying diffraction patterns.

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. II

(rocking curves) (111), (220), (333) CuK ₁ . , (111). .

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In conclusion the authors thank A. Haruý for preparing the germanium single crystals and they are indebted to V. Smutná and A. Irra for the care with which they carried out various tasks.     

Cyclotron instabilities of a two-component electron plasma

A study is made of instability at frequencies close to the electron cyclotron frequency _B and its multiples, subject to the presence of two different groups of electrons. It is shown that a mixture of hot and cold electrons ( _ph ² _pc ² ) in the region of frequencies s _B, s2 can be unstable with respect to waves of the flute type (k _z=0) with maximum increment _max ( _ph/_pc). _B, if there exists an interval of transversal velocities in whichF/ >0. When the curvature of the magnetic field is taken into account, even waves with _B can be unstable in such a plasma. The effect of spatial inhomogeneity of the hot component on flute-type instability and on two-beam cyclotron instability is also examined.The author extends his thanks to A. B. Mikhajlovskij for his valuable comments and discussions.     

РАДИОМЕТРИЯ В ГЕОФИЗ ИКЕ

cmambe ome, - . - .     

More on the τ-μ-e problem: The process e+e−→l+l− in the region of the z-resonance

Theoretical and experimental aspects of the study of the e-- problem in effects of neutral weak currents in colliding e⁺e^– beams in the region of the Z resonance are discussed. Quantities that describe the degree of violation of e-- universality are analyzed. In particular, it is shown that by measuring the spin asymmetry for angles 160° it is possible to determine the degree of violation ofl-e universality =g _A ^e g _V ^l –g _V ^e g _A ^l to an accuracy of up to 0.01.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 88-91, May, 1989.     

The energy of periodic surface structures in ferromagnetism

The periodic domain structures on unfavourably oriented surface layers of ferromagnetic materials were studied both experimentally and theoretically. The connection between the surface structure and the crystallographic orientation of the crystals was confirmed. All the terms contributing to the total energy of the surface layer were calculated. A general solution of the potential problem is given for arbitrary periodic distribution of the charges.

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The influence of plastic deformation on the magnetostriction constant of nickel

The magnetostriction constant of nickel was measured as a function of plastic deformation up to an elongation of 30%. The values of the magnetostriction constant in deformed samples deviate considerably, a fact which cannot be explained by errors of measurement. The absolute value of the magnetostriction constant decreases with increasing plastic deformation (by around 5%).

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30% . , . ( 5%).

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In conclusion the authors thank J. Kaczér, C. Sc. and B. esták, C. Sc. for carefully reading the paper and for their remarks, J. Míová for help in the measurements and workers of the chemical department of our Institute for careful preparation of the samples.     

Information theory and the problem of molecular structure

Recently it has been shown that the classical stick and ball viewpoint of molecules is inconsistent with quantum theory (QT). We suggest an unusual reconciliation: The QT state is not a physical property, but instead reflects our state of knowledge about observable aspects of reality. We show how this perspective is nevertheless objective. Applied to molecules, the view permits structure to exist only when observable evidence is compatible with this feature. Typically one must replace the a priori model (in particular, the dynamical generator) with one consistent with the evidence. We show that such structure is stable in the context of first-order perturbation theory. We also indicate how dynamics can be inferred from scattering data—a process alternative to postulating (field-theoretic) models for environment.     

Between Equilibrium Fluctuations and Eulerian Scaling: Perturbation of Equilibrium for a Class of Deposition Models

We investigate propagation of perturbations of equilibrium states for a wide class of 1D interacting particle systems. The class of systems considered incorporates zero range, K-exclusion, misanthropic, bricklayers models, and much more. We do not assume attractivity of the interactions. We apply Yau's relative entropy method rather than coupling arguments. The result is partial extension of T. Seppäläinen's recent paper. For 0<<1/5 fixed, we prove that, rescaling microscopic space and time by N, respectively N ¹⁺ , the macroscopic evolution of perturbations of microscopic order N ^– of the equilibrium states is governed by Burgers' equation. The same statement should hold for 0<<1/2 as in Seppäläinen's cited paper, but our method does not seem to work for 1/5.     

The form factors of the decays π− → e−¯veγ and K− → e−¯veγ

In the special type of the quark model we obtain the ratio=h _A/h_V of the axial (h_A) and vector (h_V) form factors for the decays ^– e^– ¯v_e and K^– e^–¯v_e different from unity. The low-energy theorem, relating the electric polarizability of the charged pion with the ratio, is analyzed. It is shown that < 1 corresponds to , calculated by accounting the contribution of the scalar meson(700) into the amplitude of the Compton effect on the pion. In the absence of the(700) contribution we have=1.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday.     

Southern galactic plane CO survey

Preliminary results are presented for a survey of J=1–0¹²CO emission being carried out at 3 arc intervals along the southern galactic plane in the range 294°358°, –0°.075b0°.075. The longitude-velocity distribution shows well-defined terminal velocities, and is similar to the distribution at corresponding longitudes north of the galactic centre. However, the radial distribution of CO suggests that the southern CO, while concentrated inside the solar circle as in the north, is on the average located about 500 pc further from the galactic centre. Limited estimates of cloud sizes and masses suggest ranges greater than those deduced in previous surveys.On leave from University of British Columbia Vancouver, B.C.     

ИЗМЕНЕНИЯ ТОНКОЙ СТР УКТУРЫ МОЛОТОГО КОБА ЛТА

- , . , , - . - , , , - .     

Interacting spinor and scalar fields: Exact self-consistent solutions in Bianci I space

Exact self-consistent solutions of the equations that describe a system of interacting spinor and massless scalar fields with the interaction Lagrangian L_int=_,^,(S), where (S) is an arbitrary function of the invariant S=, are obtained in Bianci I space. The possibility of excluding the initial singularity is studied for the case of a power-law function (S), and isotropic expansion of the space as t is established.Russian University of International Amity. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 53–58, July, 1995.     

The electroluminescence of ZnS-Cu,Mn

The brightness waves of ZnS-Cu, Mn phosphor were investigated and it was found that their shape changes from that characteristic for copper-activated phosphors to that characteristic for manganese-activated phosphors as a function of the magnitude of the voltage applied, the length of the pulses and the temperature. In order to explain the results it is assumed that simultaneously with the mechanism of electroluminescence, accepted for ZnS-Cu (ionization of activators; recombination and radiation delayed in phase compared with voltage), there exists an immediate recombination of the Cu activators in the barriers, which is accompanied by radiation in phase with the voltage.

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ZnS-Cu, Mn

ZnS-Cu, Mn. , , , , , , , , . , , ZnS-Cu ( ; , ), : Cu , , .

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In conclusion, the authors thank Dr. M. Trlifaj for valuable discussions and M. Skala for supplying the electroluminescent phosphor of ZnS-Cu, Mn.     

Adjoint solutions of the Brans-Dicke equations

It is shown that if the Brans-Dicke equations have the solution,g _ij generated by the trace free sourceT _n (T-O) then there exists an adjoint solution ^–1, ²g_ij of these equations generated by the source ^-2 T _u. An example is considered.