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N. K. Kornegrutsa

Publications and source records attributed to N. K. Kornegrutsa.

At least 19 recordsLinked to original sources
arXiv2026

Threshold resonances in relativistic $^{16}$O and $^{22}$Ne dissociation

The nuclear emulsion method is applied to study binary dissociation leading to the formation of $α$-particles from $^{16}$O nuclei at 3.65 GeV per nucleon and $^{22}$Ne nuclei at 3.22 GeV per nucleon. The invariant mass distribution for the $^{16}$O$\to$$^{12}$C(0$^+_1$)+$α$ channel indicates decays of the $^{16}$O(0$^+_6$) excitation, whose probability exceeds the estimate for the $^{12}$C(0$^+_2$)+$α$ channel by a factor of 20. The invariant mass distribution for $^{22}$Ne$\to$$^{18}$O+$α$ exhibits a peak corresponding to $^{22}$Ne excitations around 11.6 MeV.

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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

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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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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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 ${}^{12}$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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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\%.

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arXiv2015

Coherent Dissociation of Relativistic N-12 Nuclei

The dissociation of relativistic $^{12}$N nuclei having a momentum of 2 GeV/c per nucleon and undergoing the most peripheral interactions in a track emulsion is studied. The picture of charged topology of product ensembles of relativistic fragments and special features of their angular distributions are presented.

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arXiv2015

Exposure of Nuclear Track Emulsion to He-8 Nuclei at the ACCULINNA Separator

Nuclear track emulsion is exposed to a beam of radioactive $^8$He nuclei with an energy of 60 MeV and enrichment of about 80% at the ACCULINNA separator. Measurements of 278 decays of the $^8$He nuclei stopped in the emulsion allow the potential of the $α$ spectrometry to be estimated and the thermal drift of $^8$He atoms in matter to be observed for the first time.

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arXiv2014

Clustering features of the $^7$Be nucleus in relativistic fragmentation

Charge topology of fragmentation of 1.2 A GeV $^7$Be nuclei in nuclear track emulsion is presented.The dissociation channels $^4$He + $^3$He, 2$^3$He+ n, $^4$He + 2$^1$H are considered in detail. It is established that the events $^6$Be + n amount about to 27 % in the channel $^4$He + 2$^1$H.

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arXiv2014

$^8$He nuclei stopped in nuclear track emulsion

The fragment separator ACCULINNA in the G. N. Flerov Laboratory of Nuclear Reactions of JINR was used to expose a nuclear track emulsion to a beam of radioactive $^{8}$He nuclei of energy of 60 MeV and enrichment of about 80%. Measurements of decays of $^{8}$He nuclei stopped in the emulsion allow one to evaluate possibilities of $α$-spectrometry and to observe a thermal drift of $^{8}$He atoms in matter. Knowledge of the energy and emission angles of $α$-particles allows one to derive the energy distribution of $α$-decays Q$_{2α}$. The presence of a "tail" of large values Q$_{2α}$ is established. The physical reason for the appearance of this "tail" in the distribution Q$_{2α}$ is not clear. Its shape could allow one to verify calculations of spatial structure of nucleon ensembles emerging as $α$-pairs of decays via the state $^8$Be$_{2+}$.

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arXiv2011

Clustering in relativistic dissociation of $^9$be, $^9$c, $^{10}$c and $^{12}$n nuclei

The dissociation features in nuclear track emulsion of $^9$Be, $^{9,10}$C, and $^{12}$N nuclei of 1.2 A GeV energy are presented. The data presented for the nucleus $^9$Be can be considered as evidence that there is a core in its structure in the form of 0$^+$ and 2$^+$ states of the $^8$Be nucleus having roughly equal weights. Events of coherent dissociation $^9$C$\rightarrow 3^3$He associated with the rearrangement of the nucleons outside the $α$-clustering are identified. A pattern of the charge fragment topology in the dissociation of $^{10}$C and $^{12}$N nuclei is obtained for the first time. Contribution of the unbound nucleus decays to the cascade process $^{10}$C$\rightarrow ^9$B$\rightarrow ^8$Be is identified.

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