D. N. Kadrev

Bulgarian Academy of Sciences, Ulpia Serdica, Sofia-Capital, Bulgaria

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Publications (37)50.66 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The density distributions of $^{10}\mathrm{Be}$ and $^{11}\mathrm{Be}$ nuclei obtained within the quantum Monte Carlo model and the generator coordinate method are used to calculate the microscopic optical potentials (OPs) and cross sections of elastic scattering of these nuclei on protons and $^{12}\mathrm{C}$ at energies $E<100$ MeV/nucleon. The real part of the OP is calculated using the folding model with the exchange terms included, while the imaginary part of the OP that reproduces the phase of scattering is obtained in the high-energy approximation. In this hybrid model of OP the free parameters are the depths of the real and imaginary parts obtained by fitting the experimental data. The well-known energy dependence of the volume integrals is used as a physical constraint to resolve the ambiguities of the parameter values. The role of the spin-orbit potential and the surface contribution to the OP is studied for an adequate description of available experimental elastic scattering cross-section data. Also, the cluster model, in which $^{11}\mathrm{Be}$ consists of a $n$-halo and the $^{10}\mathrm{Be}$ core, is adopted. Within the latter, the breakup cross sections of $^{11}\mathrm{Be}$ nucleus on $^{9}\mathrm{Be},^{93}\mathrm{Nb},^{181}\mathrm{Ta}$, and $^{238}\mathrm{U}$ targets and momentum distributions of $^{10}\mathrm{Be}$ fragments are calculated and compared with the existing experimental data.
    Physical Review C 03/2015; 91(3). DOI:10.1103/PhysRevC.91.034606 · 3.88 Impact Factor
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    ABSTRACT: The density distributions of $^{10}$Be and $^{11}$Be nuclei obtained within the quantum Monte Carlo (QMC) model and the generator coordinate method (GCM) are used to calculate the microscopic optical potentials (OPs) and cross sections of elastic scattering of these nuclei on protons and $^{12}$C at energies $E<100$ MeV/nucleon. The real part of the OP is calculated using the folding model with the exchange terms included, while the imaginary part of the OP that reproduces the phase of scattering is obtained in the high-energy approximation (HEA). In this hybrid model of OP the free parameters are the depths of the real and imaginary parts obtained by fitting the experimental data. The well known energy dependence of the volume integrals is used as a physical constraint to resolve the ambiguities of the parameter values. The role of the spin-orbit potential and the surface contribution to the OP is studied for an adequate description of available experimental elastic scattering cross section data. Also, the cluster model, in which $^{11}$Be consists of a $n$-halo and the $^{10}$Be core, is adopted. Within the latter, the breakup cross sections of $^{11}$Be nucleus on $^{9}$Be, $^{93}$Nb, $^{181}$Ta, and $^{238}$U targets and momentum distributions of $^{10}$Be fragments are calculated and compared with the existing experimental data.
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    ABSTRACT: Theoretical analysis of the elastic scattering and breakup in interactions of the 11Li nucleus with protons are presented. The hybrid model of the microscopic optical potential (OP) is applied. The OP includes the single-folding real part, while its imaginary part is derived within the high-energy approximation (HEA) theory. The spin-orbit contribution to the OP is also included. The differential cross sections of 11Li+p elastic scattering and the total reaction cross sections are calculated at energies of 62, 68.4, and 75 MeV/nucleon and are compared with the available experimental data. The breakup cross sections at 62 MeV/nucleon and the momentum distributions of the fragments using a two cluster model of the 11 Li nucleus are obtained. An analysis of the single-particle density of 11Li is performed.
    Journal of Physics Conference Series 09/2014; 533(1):012031. DOI:10.1088/1742-6596/533/1/012031
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    ABSTRACT: In the paper, the results of analysis of elastic scattering and breakup processes in interactions of the ^{11}Li nucleus with protons are presented. The hybrid model of the microscopic optical potential (OP) is applied. This OP includes the single-folding real part, while its imaginary part is derived within the high-energy approximation theory. For ^{11}Li+p elastic scattering, the microscopic large-scale shell model (LSSM) density of ^{11}Li is used. The depths of the real and imaginary parts of the OP are fitted to the elastic scattering data at 62, 68.4, and 75 MeV/nucleon, being simultaneously adjusted to reproduce the true energy dependence of the corresponding volume integrals. The role of the spin-orbit potential is studied and predictions for the total reaction cross sections are made. Also, the cluster model, in which ^{11}Li consists of a 2n-halo and the ^{9}Li core having its own LSSM form of density, is adopted. The respective microscopic proton-cluster OPs are calculated and folded with the density probability of the relative motion of both clusters to get the whole ^{11}Li+p OP. The breakup cross sections of ^{11}Li at 62 MeV/nucleon and momentum distributions of the cluster fragments are calculated. An analysis of the single-particle density of ^{11}Li within the same cluster model accounting for the possible geometric forms of the halo-cluster density distribution is performed.
    Physical Review C 09/2013; 88(3). DOI:10.1103/PhysRevC.88.034612 · 3.88 Impact Factor
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    ABSTRACT: A microscopic optical model analysis of the 11 Li+p elastic scattering data at incident energies of 62, 68.4, and 75 MeV/nucleon has been performed utilizing the microscopic optical potentials derived by a single-folding proce-dure and also by using those inherent in the high-energy approximation. The calculated optical potentials are based on the microscopically calculated neu-tron and proton density distributions within the large-scale shell model for 11 Li. The depths of the real and imaginary parts of the microscopic optical potentials are considered as fitting parameters in relation to the behavior of the volume integrals as functions of the incident energy. The role of the spin-orbit potential is studied and estimations of the total cross sections are made.
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    ABSTRACT: Amicroscopic optical potential is used to calculate cross sections for elastic {sup 11}Li +p scattering at the energies of 62, 68.4, and 75 MeV per nucleon, and the results are compared with available experimental data. The potential used does not involve free parameters, but the depths of its real and imaginary parts are renormalized. The known trend in the energy dependence of the volume integrals of the optical potential is taken into account in analyzing experimental data. The role of spin-orbit interaction is studied, and the total reaction cross sections that are proposed to be measured in future experiments are calculated.
    Physics of Atomic Nuclei 11/2012; 75(11). DOI:10.1134/S1063778812110154 · 0.60 Impact Factor
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    ABSTRACT: Theoretical analysis is made for the 6He+12C elastic scattering data at three different beam energies. The breakup effect of the 6He at higher energies is also studied. Calculations were performed using microscopic optical potentials (OP's) obtained by a double-folding procedure and also those inherent in the high-energy Glauber-Sitenko approximation. The problem of ambiguity of the adjusted depths of these potentials is resolved. The role of breakup processes in formation of the imaginary potential in elastic channel is also discussed.
    Journal of Physics Conference Series 05/2012; 366(1). DOI:10.1088/1742-6596/366/1/012032
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    D.n.kadrev · A.n.antonov · M.v.stoitsov · S.s.dimitrova
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    ABSTRACT: Natural orbitals obtained within the coherent density fluctuation model and containing nucleon correlation effects are used to calculate characteristics of the A-nucleon system, such as the electron elastic magnetic scattering form factors. The calculations are performed for nuclei with a doubly-closed core and a valence nucleon in a stretched configuration (j=l+1/2), such as the 17O and 41Ca nuclei. It is shown that the calculations of the transverse form factor using natural orbitals improve the agreement with the experimental data in comparison with the case when shell-model single-particle wave functions are used.
    International Journal of Modern Physics E 01/2012; 05(04). DOI:10.1142/S0218301396000396 · 0.84 Impact Factor
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    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 05/2011; 637(1):60–76. · 1.32 Impact Factor
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    ABSTRACT: The electron–ion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 05/2011; 637(1):60-76. DOI:10.1016/j.nima.2010.12.246 · 1.32 Impact Factor
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    ABSTRACT: The 6He + 12C elastic scattering at E = 3.0, 38.3, and 41.6 MeV/nucleon is analyzed using the microscopic model of optical potential. According to this approach, two or three parameters are fitted that renormalize the depth of real, imaginary, and surface parts of the calculated optical potential. In this case, the ambiguity of the obtained sets of fitting parameters remains, but can be reduced by introducing an additional criterion of selection: the dependence of the volume integrals of the optical potential on the energy. The structure of the obtained optical potential, the role of the nuclear medium, the formation of the imaginary part of the optical potential, and the interconnection between the surface potential and the 6He breakup channels are discussed.
    Bulletin of the Russian Academy of Sciences Physics 04/2011; 75(4):495-499. DOI:10.3103/S1062873811040319
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    ABSTRACT: The He6+C12 elastic scattering data at beam energies of 3,38.3, and 41.6 MeV/nucleon are studied utilizing the microscopic optical potentials obtained by a double-folding procedure and also by using those inherent in the high-energy approximation. The calculated optical potentials are based on the neutron and proton density distributions of colliding nuclei established in an appropriate model for He6 and obtained from the electron scattering form factors for C12. The depths of the real and imaginary parts of the microscopic optical potentials are considered as fitting parameters. At low energy the volume optical potentials reproduce sufficiently well the experimental data. At higher energies, generally, additional surface terms having the form of a derivative of the imaginary part of the microscopic optical potential are needed. The problem of ambiguity of adjusted optical potentials is resolved requiring the respective volume integrals to obey the determined dependence on the collision energy. Estimations of the Pauli blocking effects on the optical potentials and cross sections are also given and discussed. Conclusions on the role of the aforesaid effects and on the mechanism of the considered processes are made.
    Physical Review C 07/2010; 82(2). DOI:10.1103/PhysRevC.82.024604 · 3.88 Impact Factor
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    ABSTRACT: A microscopic approach to calculate the optical potential (OP) with the real part obtained by a folding procedure and with the imaginary part inherent in the high-energy approximation is applied to study the 8He+p elastic scattering at energies of tens of MeV/nucleon (MeV/N). The OP's and the cross sections are calculated using different models for the neutron and proton densities of 8He. The role of the spin-orbit potential is studied. Comparison of the calculations with the available experimental data on the elastic scattering differential cross sections at beam energies of 15.7, 26, 32, 66 and 73 MeV/N is performed. The problem of the ambiguities of the depths of each component of the optical potential is considered by means of the imposed physical criterion related to the known behavior of the volume integrals as functions of the incident energy. It is shown also that the role of the surface absorption is rather important, in particular for the lowest incident energies (e.g., 15.7 and 26 MeV/N). The present approach, which uses only parameters that renormalize the depths of the OP, can be applied along with other methods using microscopically calculated optical potentials.
    Journal of Physics Conference Series 02/2010; 205(1):012032. DOI:10.1088/1742-6596/205/1/012032
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    ABSTRACT: An approach to calculate microscopic optical potential with the real part obtained by a folding procedure and with the imaginary part inherent in the high-energy approximation is applied to study the He8+p elastic-scattering data at energies of tens of MeV/nucleon. The neutron and proton density distributions obtained in different models for He8 are used in the calculations of the differential cross sections. The role of the spin-orbit potential is studied. Comparison of the calculations with the available experimental data on the elastic-scattering differential cross sections at beam energies of 15.7, 26.25, 32, 66, and 73 MeV/nucleon is performed. The problem of the ambiguities of the depths of each component of the optical potential is considered by means of the imposed physical criterion related to the known behavior of the volume integrals as functions of the incident energy. It is shown also that the role of the surface absorption is rather important, in particular for the lowest incident energies (e.g., 15.7 and 26.25 MeV/nucleon).
    Physical Review C 08/2009; 80(2). DOI:10.1103/PhysRevC.80.024609 · 3.88 Impact Factor
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    ABSTRACT: A microscopic approach to calculate the optical potential (OP) with the real part obtained by a folding procedure and with the imaginary part inherent in the high-energy approximation (HEA) is applied to study the 6,8He+p elastic scattering data at energies of tens of MeV/N. The OP's and the cross sections are calculated using different models for the neutron and proton densities of 6,8He. The role of the spin-orbit (SO) potential and effects of the energy and density dependence of the effective NN forces are studied. Comparison of the calculations with the available experimental data on the elastic scattering differential cross sections at beam energies
    08/2009; DOI:10.1063/1.3232112
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    ABSTRACT: The optical potential of 8He+p scattering is calculated using the folding model for its real part and the high-energy approximation for the imaginary part. On this basis, the experimental differential elastic scattering cross sections are analyzed at energies below 100 MeV/nucleon. Conclusions are drawn on the applicability of the optical potential model and on the selection of an adequate model of the 8He nucleus structure.
    Bulletin of the Russian Academy of Sciences Physics 07/2009; 73(6):840-844. DOI:10.3103/S1062873809060306
  • Y. Watanabe · D.N. Kadrev
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    ABSTRACT: A quantum molecular dynamics (QMD) model is applied to production of light charged particles in nucleon-induced reactions on several light and medium heavy nuclei. The generalized evaporation model (GEM) is used to deal with the statistical decay process of highly excited fragments at the end of the QMD stage. Good agreement with experimental double-differential cross sections is obtained for nucleon emission, but the calculation shows remarkable underprediction for preequilibrium emission of light complex particles, i.e., d, t, 3He, and 4He. To improve the situation, a phenomenological surface coalescence model is incorporated into the QMD simulation under the assumption that light complex particles are mainly formed near the surface region by a leading nucleon that is ready to escape from the nucleus during the dynamical process.
  • Y Watanabe · D N Kadrev
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    ABSTRACT: A quantum molecular dynamics (QMD) simulation is applied to light-ion production in neutron-induced reactions on O, Si and Fe at E(n) = 96 MeV. The generalized evaporation model (GEM) is used to account for statistical decay processes after the QMD stage. Good agreement with the experimental energy spectra is obtained for proton emission, but the calculation exhibits remarkable underestimation for pre-equilibrium emission of light clusters, i.e. d, t, (3)He and (4)He. It is found that the underestimation is improved except in the region around the high energy end of the emission spectra by implementation of a phenomenological coalescence model into the QMD under the assumption that these light clusters are formed in the nuclear surface region by a leading nucleon that is ready to leave the nucleus.
    Radiation Protection Dosimetry 02/2007; 126(1-4):40-4. DOI:10.1093/rpd/ncm010 · 0.86 Impact Factor
  • International Nuclear Physics Conference (INPC), June 3-8, 2007, Tokyo, Japan; 01/2007

Publication Stats

226 Citations
50.66 Total Impact Points

Institutions

  • 2000–2015
    • Bulgarian Academy of Sciences
      • Institute for Nuclear Research and Nuclear Energy (INRNE)
      Ulpia Serdica, Sofia-Capital, Bulgaria
  • 2008
    • Kyushu University
      Hukuoka, Fukuoka, Japan
  • 2002–2004
    • Institute for Nuclear Research and Nuclear Energy
      Ulpia Serdica, Sofia-Capital, Bulgaria