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P. I. Zarubin

Publications and source records attributed to P. I. Zarubin.

At least 19 recordsLinked to original sources
arXiv2026

The $^{8}$Be nucleus and the Hoyle state in dissociation of relativistic nuclei

The possibility of recording fragmentation events of relativistic nuclei in a nuclear emulsion, discovered back in the pioneering era of cosmic ray physics, opens up the prospect of using this method to study extremely cold ensembles of H and He nuclei in the interests of developing the physics of nuclear clustering and, possibly, expanding the scenarios of nuclear astrophysics. The results of the BECQUEREL experiment at JINR, obtained on unstable states in the relativistic dissociation of nuclei in a nuclear emulsion providing complete detection of fragments with record resolution are presented. According to the invariant masses calculated from the emission angles in the fragmentation cone, the decays of $^8$Be(0$^+$), $^8$Be(2$^+$), $^9$Be(1.7), $^9$B, $^6$Be, $^{12}$C(0$^+_2$) or the Hoyle state and $^{12}$C(3$^-$) have been identified. The contribution of $^8$Be(0$^+$), $^9$B and $^{12}$C(0$^+_2$) increases rapidly with the $α$-particle multiplicity. Their structure and the diversity of parent nuclei suggest the fusion of the latter. The usage of automated microscopy for an analysis of exposures at the JINR NICA accelerator complex becomes a modern basis to apply the nuclear emulsion method.

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arXiv2025

Current problems of studying relativistic dissociation of light nuclei in nuclear emulsion

The progress of the study of unstable states in relativistic dissociation events of light nuclei in nuclear emulsion is presented. Identification of these states is possible by means of the invariant mass determined from the most accurate and complete measurements of relativistic fragment emission angles in the approximation of conservation of momentum per nucleon of the parent nucleus. It is established that excitations $^{12}\mathrm{C}(0^{+}_{2})$ and $^{12}\mathrm{C}(3^{-})$ lead in the dissociation $^{12}\mathrm{C} \rightarrow 3α$ and $^{16}\mathrm{O} \rightarrow 4α$. The contribution of $^{9}\mathrm{B}$ and $^{12}\mathrm{C}(0^{+}_{2})$ decays to the leading channel of $^{3}\mathrm{HeH}$ dissociation of the $^{14}\mathrm{N}$ nucleus is estimated. The motivation and the beginning of the analysis of the relativistic dissociation $^{16}\mathrm{O}$$\rightarrow$$^{12}\mathrm{C}α$ are presented. The presented relativistic dissociation events at the $^{7}\mathrm{Be}$$\rightarrow$$^{6}\mathrm{Li}p$ and $^{11}\mathrm{C}$$\rightarrow$$ ^{7}\mathrm{Be}α$ coupling threshold point to the prospect of moving beyond $α$-particle clustering.

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arXiv2024

On formation of the $^{12}$C(0$^+_2$) and $^{12}$C(3$^-$) states in relativistic dissociation of light nuclei

The formation of the excited states $^{12}$C(0$^+_2$) and $^{12}$C(3$^-$) is investigated in the dissociation of $^{12}$C $\to$ 3$α$ and $^{16}$O $\to$ 4$α$ at the energy of 3.65 GeV per nucleon in the nuclear emulsion. The identification becomes possible by reconstructing the invariant mass from measurements of emission angles in the approximation of conservation of momentum per nucleon of the parent nucleus. The contribution of the decays $^{12}$C(0$^+_2$) and $^{12}$C(3$^-$) to the dissociation $^{12}$C $\to$ 3$α$ is 11 and 19%, and in $^{16}$O $\to$ 4$α$ it is - 20 and 30%, correspondingly.

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arXiv2024

Study of the Involvement of $^8$Be and $^9$B Nuclei in the Dissociation of Relativistic $^{10}$C, $^{10}$B, and $^{12}$C Nuclei

The results obtained by estimating the contribution of $^8$Be and $^9$B nuclei to the coherent dissociation of $^{10}$C, $^{10}$B, and $^{12}$C relativistic nuclei in nuclear track emulsions (``white'' stars) are presented. The selection of ``white'' stars accompanied by $^9$B leads to a distinct peak appearing in the distribution of the excitation energy of 2$α$2$p$ ensembles and having a maximum at 4.1 $\pm$ 0.3 MeV. A $^8$Be nucleus manifests itself in the coherent-dissociation reaction $^{10}$B $\to$ 2He + H with a probability of (25 $\pm$ 5)\%, (14 $\pm$ 3)\% of it being due to $^9$B decays. The ratio of the branching fractions of the $^9$B + $n$ and $^9$Be + $p$ mirror channels is estimated at 6 $\pm$ 1. An analysis of the relativistic dissociation of $^{12}$C nuclei in a nuclear track emulsion revealed nine 3$α$ events corresponding to the Hoyle state.

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arXiv2024

Dissociation of Relativistic $^{10}$B Nuclei in Nuclear Track Emulsion

The structural features of $^{10}$B are studied by analyzing the dissociation of nuclei of this isotope at an energy of 1 A GeV in nuclear track emulsion. The fraction of the $^{10}$B $\to$ 2He + H channel in the charge state distribution of fragments is 78\%. It was determined based on the measurements of fragment emission angles that unstable $^{8}$Be$_{g.s.}$ nuclei appear with a probability of (26 $\pm$ 4)\%, and (14 $\pm$ 3)\% of them are produced in decays of an unstable $^9$B$_{g.s.}$ nucleus. The Be + H channel was suppressed to approximately 1\%.

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arXiv2024

Highlights of Unstable States in Relativistic Dissociation of Light Nuclei in Nuclear Emulsion

The results of the study of unstable states in relativistic dissociation of isotopes $^{9,7}$Be, $^{10}$B, $^{12,11,10}$C, $^{14}$N and $^{16}$O in nuclear emulsion have been summarized. Their decays are identified in distributions by invariant masses determined by fragment emission angles in the velocity conservation approximation. The observed diversity enables us to assume universality in the formation of nuclear-molecular states near the bond thresholds as a consequence of coalescence of emerging $α$-particles and nucleons.

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arXiv2024

Fragmentation of 1.2 A GeV $^7$Be nuclei in nuclear photographic emulsion

The charge topology of peripheral fragmentation of 1.2 A GeV $^7$Be nuclei in a nuclear emulsion is presented. The dissociation of $^7$Be nuclei via the channels $^7$Be$\rightarrow ^4$He + $^3$He, $^7$Be$\rightarrow$2$^3$He + n and $^7$Be$\rightarrow ^4$He + 2$^1$H is considered in detail. It is found that in the channel $^7$Be$\rightarrow ^4$He + 2$^1$H, events related to the channel $^7$Be$\rightarrow ^6$Be + n with the cascade decay $^6$Be$\rightarrow ^4$He + 2p account for about 27 %.

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arXiv2024

From the first observations of cosmic rays to the physics of relativistic nuclei

Research of cosmic rays at the Physical Institute of the USSR Academy of Sciences resulted in the construction of the JINR Synchrophasotron. For this purpose the Electrophysical Laboratory of the USSR Academy of Sciences was founded in 1953, which became part of JINR in 1956 as the High Energy Laboratory. The initial milestones to develop experiments at the Laboratory on the Synchrophasotron are presented. Leaders and key participants in the experiments are highlighted, as well as the lessons and results relevant today.

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arXiv2023

Cosmophysical aspects of relativistic nuclear fragmentation

The status of the study of multiple fragmentation of 950 MeV per nucleon Kr nuclei in a nuclear track emulsion aimed at determining the contributions of 2$α$ decays of $^{8}$Be, the Hoyle 3$α$ state, and the search for a 4$α$ particle condensate state, is presented. In events with the production of few relativistic fragments of He and H, the possibility of estimating the multiplicity of neutrons in the fragmentation cone of a projectile nucleus is studied. For the planar component of neutron transverse momenta estimated from the angles of observed secondary stars, the Rayleigh distribution parameter was 35 $\pm$ 7 MeV/$c$. The importance of such events for the interpretation of cosmophysical observations is noted.

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arXiv2022

An enhancement of formation of unstable $^{8}$Be nucleus with the growth of $α$-particle multiplicity in fragmentation of relativistic nuclei

In this paper, the correlation between the formation of the unstable $^{8}$Be nucleus and accompanying $α$ particles in the fragmentation of relativistic $^{16}$O, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei in a nuclear track emulsion is investigated. The $^{8}$Be decays are identified in a wide energy range by invariant masses calculated from 2$α$-pair opening angles. The adopted approximations are verified by data on fragmentation of $^{16}$O nuclei in a hydrogen bubble chamber in a magnetic field. An increase in the $^{8}$Be contribution to the dissociation with the growth of $α$-particle multiplicity is found.

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arXiv2022

Prospects of searching for unstable nucleus states in relativistic nuclear fragmentation

The article is dedicated to the experimental study in the relativistic approach to the problems of nuclear cluster physics for the prospects of the \href{http://becquerel.jinr.ru/}{BECQUEREL} experiment. The nuclear emulsion method applied in this experiment makes it possible to study thoroughly the relativistic final states in the fragmentation of nuclei. The focus of the presented research is the dynamics of emergence of the $^{8}$Be nucleus and the Hoyle state, as well as the search for the 4$α$-particle condensate decaying via the above nuclear states. In this context, the analysis of exposure to $^{84}$Kr nuclei at 950 MeV/nucleon is shown. As a continuation of the study of light nuclei, we have demonstrated the search for the isobar-analogue state of the $ ^{13} $N nucleus in the fragmentation of $ ^{14} $N nuclei at 2 GeV/nucleon.

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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.

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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.

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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.

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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.

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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\%.

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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) \%.

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