Nontrivial manifestation of clustering in fission of heavy nuclei at low and middle excitations

An analysis of the preferable fission path manifesting itself as a fine structure of the total kinetic energy-mass distribution of the fission fragments compelled us to put forward an absolutely new shape of the fissioning system on the descent from the fission barrier. It is a multicomponent nuclear molecule constituted by two magic clusters and a torus-like neck between.     

On some inverse problems for a linearized system of heat and mass transfer

In the article, we examine well-posedness of the problem on determining the source functions in a linearized system of heat and mass transfer. The overdetermination conditions are the values of concentrations on some surfaces or at separate points of the spatial domain.     

On some classes of inverse problems for parabolic and elliptic equations

We study solvability of inverse problems of finding the right-hand side together with a solution itself for vector-valued parabolic and elliptic equations. The usual boundary conditions are supplemented with the overdetermination conditions that are the values of a solution on some system of surfaces.     

Search for the ternary cluster decay of Cm isotopes using SSNTD

Investigation of the ²⁴⁶Cm spontaneous ternary decay into nearly equal clusters using polyethyleneterephthalate track detectors has been carried out. The possibility of ternary cluster decay has been found out to be of less than 10⁻⁶ with respect to all fission modes of ²⁴⁶Cm.     

Photoconductivity of gallium arsenide irradiated with 5 MeV protons

Several levels which develop in GaAs before and after proton irradiation were derived from the photoconductivity spectra. It is assumed that the majority of the levels which are observed after irradiation are related to uncontrollable impurities or to impurities which are activated during irradiation. The GaAs Cu samples were used to show that it is possible to activate admixtures by proton irradiation. It was established that the absolute photoconductivity is reduced during irradiation by the development of recombination centers. The average activation energy of these centers was estimated at 0.06 eV. Lattice defects are the recombination centers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 34–40, February, 1972.     

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.     

Boundary Value and Inverse Problems for Some Classes of Nonclassical Operator-Differential Equations

We consider the solvability of boundary value problems and some inverse problems for operator-differential equations of odd order which can be referred to as mixed type equations since the coefficient of the higher order time derivative can change sign. Studying the general classes of boundary value problems with nonlocal boundary conditions, we establish the existence and uniqueness theorems of regular solutions under some conditions on data.

     

On some classes of inverse problems with overdetermination data on spatial manifolds

We consider the question of well-posedness of the inverse problems of determining the righthand side (a source function) of a special form of a parabolic system of equations. The overdetermination data are the values of a solution and its normal derivatives on a system of surfaces in a spatial domain. In particular, the cross-sections of the domain can be used as these surfaces. Sharp conditions are presented for the data of the problem to ensure well-posedness.     

On some inverse problems for elliptic equations and systems

Under study are the inverse problems of determining the right-hand side of a particular form and the solution for elliptic systems, including a series of elasticity systems. (On the boundary of the domain the solution satisfies either the Dirichlet conditions or mixed Dirichlet-Neumann conditions.) We assume that on a system of planes the normal derivatives of the solution can have discontinuities of the first kind. The conjugating boundary conditions on the discontinuity surface are analogous to the continuity conditions for the fields of displacements and stresses for a horizontally laminated medium. The overdetermination conditions are integral (the average of the solution over some domain is specified) or local (the values of the solution on some lines are specified). We study the solvability conditions for these problems and their Fredholm property.