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A. A. Zaitsev

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

32 records · Page 2Linked to original sources
arXiv2021

Enhanced production of $^{8}$Be nuclei in relativistic nuclei fragmentation

This article is dedicated to the results of early measuring fragmentation of relativistic $^{16}$O, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei in a nuclear track emulsion. It has been found that there is a contribution of the unstable $^8$Be nucleus decays to $α$-particle multiplicities. These renewed measurements of nuclear track emulsion exposed to $^{84}$Kr nuclei at the energy of 950 MeV per nucleon have been analyzed and given below.

nucl-ex↗
arXiv2021

Correlation in formation of $^{8}$Be nuclei and $α$-particles in fragmentation of relativistic nuclei

In the events of peripheral dissociation of relativistic nuclei in the nuclear track emulsion, it is possible to study the emerging ensembles of He and H nuclei, including those from decays of unstable $^{8}$Be and $^{9}$B nuclei, as well as the Hoyle state. These extremely short-lived states are identified by invariant masses calculated from the angles in 2$α$-pairs, 2$αp$- and 3$α$-triplets in the approximation of conservation of momentum per nucleon of the primary nucleus. In the same approach, it is possible to search for more complex states. This paper explores the correlation between the formation of $^{8}$Be nuclei and the multiplicity of accompanying $α$-particles in the dissociation of relativistic $^{16}$O, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei. On the above basis, estimates of this correlation are presented for the unstable $^{9}$B nucleus and the Hoyle state. The enhancement in the $^{8}$Be contribution to dissociation with the $α$-particle multiplicity has been found. Decays of $^{9}$B nuclei and Hoyle states follow the same trend.

nucl-ex↗
arXiv2021

Ratio of cross-sections of kaons to pions produced in $pp$ collisions as a function of $\sqrt{s}$

A calculation of the inclusive spectra of pions and kaons produced in $pp$ collisions as functions of their transverse momentum $p_t$ at mid-rapidity is presented within the self-similarity approach. A satisfactory description of the data within a wide range of initial energies is presented. We focus mainly on the ratio of cross-sections of $K^\pm$ to $π^\pm$ mesons produced in $pp$ collisions as a function of $\sqrt{s}$. A fast rise of this ratio, when the initial energy increases starting from the kaon production threshold up to $\sqrt{s}\simeq$ 20-30 Gev, is revealed together with its very slow increase up to LHC energies. The energy dependence of this ratio is due to the conservation laws of four-momenta and quantum numbers of the initial and produced hadrons, and to the Regge behavior of cross-sections at large energies. The more or less satisfactory agreement of these ratios with NA61-SHINE, RHIC and LHC data is demonstrated.

hep-ph↗
arXiv2020

Search for decays of the $^{9}$B nucleus and Hoyle state in $^{14}$N nucleus dissociation

First results of an analysis to determine contribution of decays of the unstable $^{8}$Be and $^{9}$B nuclei and the Hoyle 3$α$-state to dissociation of $^{14}$N $\to$ 3He (+H) are presented. As the research material, layers of nuclear track emulsion longitudinally exposed to 2.9 $A$ GeV/$c$ $^{14}$N nuclei with at the JINR Nuclotron. Under the assumption that the He and H fragments retain momentum per nucleon of the primary nucleus, these unstable states are identified by the invariant mass calculated from the emission angles of the fragments.

nucl-ex↗
arXiv2020

Unstable states in dissociation of relativistic nuclei. Recent findings and prospects of researches

The invariant mass method is used to identify the $^8$Be and $^9$B nuclei and Hoyle state formed in dissociation of relativistic nuclei in a nuclear track emulsion. It is shown that to identify these extremely short-lived states in the case of the isotopes $^9$Be, $^{10}$B, $^{10}$C, $^{11}$C, $^{12}$C, and $^{16}$O, it is sufficient to determine the invariant mass as a function of the angles in pairs and triples of He and H fragments in the approximation of the conservation of momentum per nucleon of the parent nucleus. According to the criteria established in this way, the contribution of these three unstable states was evaluated in the relativistic fragmentation of the $^{28}$Si and $^{197}$Au nuclei.

nucl-ex↗
arXiv2019

The Hoyle state in relativistic dissociation of light nuclei

In the context of the search for triples of relativistic $α$-particles in the Hoyle state, the analysis of available data on the dissociation of the nuclei ${}^{12}$C, ${}^{16}$O and ${}^{22}$Ne in the nuclear emulsion was carried out. The Hoyle state is identified by the invariant mass calculated from pair angles of expansion in $α$-triples in the approximation of the conservation of the momentum per nucleon of the parent nucleus. The contribution of the Hoyle state to the dissociation of ${}^{12}$C $\to$ 3$α$ is 11\%. In the case of the coherent dissociation of ${}^{16}$O $\to$ 4$α$ it reaches 22\% when the portion of the channel ${}^{16}$O $\to$ 2${}^{8}$Be is equal to 5\%.

nucl-ex↗
arXiv2019

The Hoyle State in Relativistic ${}^{12}$C Dissociation

Production of $α$-particle triples in the Hoyle state (HS) in dissociation of ${}^{12}$C nuclei at 3.65 and 0.42 $A$ GeV in nuclear track emulsion is revealed by the invariant mass approach. Contribution of the HS to the dissociation ${}^{12}$C $\to$ 3$α$ is (11 $\pm$ 3) \%. Reanalysis of data on coherent dissociation ${}^{16}$O $\to$ 4$α$ at 3.65 $A$ GeV is revealed the HS contribution of (22 $\pm$ 2) \%.

nucl-ex↗
arXiv2019

Toward ternary fission accompanied by the ${}^{8}$Be nucleus

Experiments in preparation for search for uranium ternary fission by means of nuclear track emulsion are summarized. The study will be focused on the possible involvement of the unstable nucleus ${}^{8}$Be in the suggested scenario of the collinear tri-partition in the fission.

nucl-ex↗
arXiv2018

Nuclear track emulsion in search for the Hoyle-state in dissociation of relativistic ${}^{12}$C nuclei

Production of ensembles of $α$-particle triples associated with the Hoyle state (the second excited state of the ${}^{12}$C nucleus) in peripheral dissociation of relativistic ${}^{12}$C nuclei is studied. Stacks of nuclear track emulsion pellicles exposed to ${}^{12}$C with an energy from hundreds MeV to a few GeV per nucleon serve as the material for studies. The Hoyle state decays are reconstructed via measurement of emission angles of $α$ particles with the precision sufficient for identification of the unstable ${}^{8}$Be nucleus. The estimate of the contribution of Hoyle's state to the ${}^{12}$C $\to$ 3$α$ dissociation is 10-15\%.

nucl-ex↗
arXiv2016

Unstable nuclei in dissociation of light stable and radioactive nuclei in nuclear track emulsion

A role of the unstable nuclei ${}^{6}$Be, ${}^{8}$Be and ${}^{9}$B in the dissociation of relativistic nuclei ${}^{7,9}$Be, ${}^{10}$B and ${}^{10,11}$C is under study on the basis of nuclear track emulsion exposed to secondary beams of the JINR Nuclotron. Contribution of the configuration ${}^{6}$Be + $\mit{n}$ to the ${}^{7}$Be nucleus structure is 8 $\pm$ 1% which is near the value for the configuration ${}^{6}$Li + $\mit{p}$. Distributions over the opening angle of $α$-particle pairs indicate to a simultaneous presence of virtual ${}^{8}$Be$_{g.s.}$ and ${}^{8}$Be$_{2^+}$ states in the ground states of the ${}^{9}$Be and ${}^{10}$C nuclei. The core ${}^{9}$B is manifested in the {${}^{10}$C} nucleus with a probability of 30 $\pm$ 4%. Selection of the ${}^{10}$C "white" stars accompanied by ${}^{8}$Be$_{g.s.}$ (${}^{9}$B) leads to appearance in the excitation energy distribution of 2$α$2$\mit{p}$ "quartets" of the distinct peak with a maximum at 4.1 $\pm$ 0.3 MeV. ${}^{8}$Be$_{g.s.}$ decays are presented in 24 $\pm$ 7% of 2He + 2H events of the ${}^{11}$C coherent dissociation and 27 $\pm$ 11% of the 3He ones. The channel ${}^{9}$B + H amounts 14 $\pm$ 3%. The ${}^{8}$Be$_{g.s.}$ nucleus is manifested in the coherent dissociation ${}^{10}$B $\to$ 2He + H with a probability of 25 $\pm$ 5% including 14 $\pm$ 3% of ${}^{9}$B decays. A probability ratio of the mirror channels ${}^{9}$B + $\mit{n}$ and ${}^{9}$Be + $\mit{p}$ is estimated to be 6 $\pm$ 1.

nucl-ex↗
arXiv2016

Toward an automated analysis of slow ions in nuclear track emulsion

Application of the nuclear track emulsion technique (NTE) in radioactivity and nuclear fission studies is discussed. It is suggested to use a HSP-1000 automated microscope for searching for a collinear cluster tri-partition of heavy nuclei implanted in NTE. Calibrations of $α$-particles and ion ranges in a novel NTE are carried out. Surface exposures of NTE samples to a ${}^{252}$Cf source started. Planar events containing fragments and long-range $α$-particles as well as fragment triples only are studied. NTE samples are calibrated by ions Kr and Xe of energy of 1.2 and 3 A MeV.

physics.ins-det↗
arXiv2015

Irradiation of Nuclear Track Emulsions with Thermal Neutrons, Heavy Ions, and Muons

Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n$_{th} + ^{10}$B $\rightarrow ^{7}$Li $+ (γ) + α$ were studied in nuclear tack emulsions enriched in boron. Nuclear track emulsions were also irradiated with $^{86}$Kr$^{+17}$ and $^{132}$Xe$^{+26}$ of energy about 1.2 MeV per nucleon. Measurements of ranges of heavy ions in nuclear track emulsions made it possible to determine their energies on the basis of the SRIM model. The formation of high-multiplicity nuclear stars was observed upon irradiating nuclear track emulsions with ultrarelativistic muons. Kinematical features studied in this exposure of nuclear track emulsions for events of the muon-induced splitting of carbon nuclei to three alpha particles are indicative of the nuclear-diffraction interaction mechanism.

nucl-ex↗
arXiv1999

Division of Differential operators, intertwine relations and Darboux Transformations

The problem of a differential operator left- and right division is solved in terms of generalized Bell polinomials for nonabelian differential unitary ring. The definition of the polinomials is made by means of recurrent relations. The expresions of classic Bell polinomils via generalized one is given. The conditions of an exact factorization possibility leads to the intertwine relation and results in some linearizable generalized Burgers equation. An alternative proof of the Matveev theorem is given and Darboux - Matveev transformations formula for coefficients follows from the intertwine relations and also expressed in the generalized Bell polinomials.

math-ph↗