arXiv subjects

A. A. Alexandrov

Publications and source records attributed to A. A. Alexandrov.

3 recordsLinked to original sources

arXiv2020

Refined scenario of the collinear cluster tri-partition mode with the greatest yield

In our previous publications we discussed various manifestations of a new decay channel of the low excited heavy nuclei called collinear cluster tri-partition (CCT). The most populated CCT mode was revealed in the mass correlation distribution of fission fragments (FFs) as a local region ("bump") of increased yields below the loci linked to the conventional binary fission. The bump was dubbed "Ni-bump" because it is centered at the masses associated with the magic isotopes of Ni. Intriguing features of the CCT, especially high collinearity of the CCT partners and relatively high probability comparable with that typical for conventional ternary fission, have caused rather wide discussion. In the majority of dedicated publications, the FFs partitions from the Ni-bump have been analyzed from the different points of view. In our publications, we have underlined that Ni-bump manifests itself at the detectable level only in the spectrometer arm that faces the source backing. So far, this fact has been left beyond the scope of all known theoretical considerations, while the backing likely plays a crucial role in the observation of the CCT experimental pattern.

nucl-ex↗

arXiv2020

Quantum Gases of Dipoles, Quadrupoles and Octupoles in Gross-Pitaevskii Formalism with Form Factor

Classical and quantum field theory of dipolar, axisymmetric quadrupolar and octupolar Bose gases is considered within a general approach. Dipole, axisymmetric quadrupole and octupole interaction potentials in the momentum representation are calculated. These results clearly demonstrate attraction and repulsion areas in corresponding gases. Then the Gross-Pitaevskii (GP) equation, which plays a key role in the present paper, is derived from the corresponding functional. The zoology of the form factors appearing in GP equation is studied in details. The classes of proper for the description of spatially non-uniform condensates form factors are chosen. In the Thomas-Fermi approximation a general solution of the GP equation with a quasilocal form factor is obtained. This solution has an interesting form in terms of a double rapidly converging series that universally includes all the interactions considered. An important analysis of the condensate stability, in other words the study of condensate excitations, is also performed in this paper. In the Gaussian approximation (from the GP functional), a functional describing the perturbations of the condensate is derived in details. For a probe wave function in the form of a plane wave, a spectrum of Bogoliubov excitations was obtained, from which an equation describing the threshold momentum for the emergence of instability was derived. An important result of this paper is the dependence of the threshold on the momentum of a stationary condensate. For completeness of the presentation, the approximating expression in the form of a rapidly converging series is obtained for the corresponding dependence. Finally, in the conclusion a quantum hydrodynamic theory for dipolar, axisymmetric quadrupolar and octupolar gases is briefly presented, giving a clue to the experimental determination of the form factors.

cond-mat.stat-mech↗

arXiv2017

Examination of evidence for collinear cluster tri-partition

In a series of the experiments at different time-of-flight spectrometers of heavy ions we have observed manifestations of a new at least ternary decay channel of low excited heavy nuclei. Due to specific features of the effect, it was called collinear cluster tri-partition (CCT). The experimental results obtained initiated a number of theoretical articles dedicated to different aspects of the CCT. We compare theoretical predictions with our experimental data, only partially published so far. The model of one of the most populated CCT modes that gives rise to the so called "Ni-bump" is discussed. Detection of the 68-72Ni fission fragments with a kinetic energy E<25 MeV at the mass-separator Lohengrin is proposed for an independent experimental verification of the CCT.

nucl-ex↗