Modeling near-barrier collisions of heavy ions based on a Langevin-type approach

Карпов, А. В.; Saiko, V. V.

doi:10.1103/physrevc.96.024618

Cited by 143 publications

(107 citation statements)

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“…Mass-angle correlations could be used to experimentally isolate the fragments influenced by N = 56 octupole shell gaps.On the theory side, quasifission has been studied with various approaches. This includes classical methods such as a transport model [34], the dinuclear system model [35][36][37][38], and models based on the Langevin equation [39][40][41][42][43]. Microscopic approaches such as quantum molecular dynamics [44][45][46] and the time-dependent Hartree-Fock (TDHF) theory [17,18,32,43,[47][48][49][50][51][52][53][54][55][56][57] have also been used.…”

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confidence: 99%

Deformed shell effects in Ca48+Bk249 quasifission fragments

2019

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Background: Quasifission is the main reaction channel hindering the formation of superheavy nuclei (SHN). Its understanding will help to optimize entrance channels for SHN studies. Quasifission also provides a probe to understand the influence of shell effects in the formation of the fragments. Purpose: Investigate the role of shell effects in quasifission and their interplay with the orientation of the deformed target in the entrance channel. Methods: 48 Ca+ 249 Bk collisions are studied with the time-dependent Hartree-Fock approach for a range of angular momenta and orientations. Results: Unlike similar reactions with a 238 U target, no significant shell effects which could be attributed to 208 Pb "doubly-magic" nucleus are found. However, the octupole deformed shell gap at N = 56 seems to strongly influence quasifission in the most central collisions.Conclusions: Shell effects similar to those observed in fission affect the formation of quasifission fragments. Mass-angle correlations could be used to experimentally isolate the fragments influenced by N = 56 octupole shell gaps.On the theory side, quasifission has been studied with various approaches. This includes classical methods such as a transport model [34], the dinuclear system model [35][36][37][38], and models based on the Langevin equation [39][40][41][42][43]. Microscopic approaches such as quantum molecular dynamics [44][45][46] and the time-dependent Hartree-Fock (TDHF) theory [17,18,32,43,[47][48][49][50][51][52][53][54][55][56][57] have also been used. See [58][59][60][61] for recent reviews on TDHF.An advantage of microscopic calculations is that their only inputs are the parameters of the energy density functional describing the interaction between the nucleons. Since these parameters are usually fitted on nuclear structure properties only, such calculations do not require additional parameters determined from reaction mechanisms, such as nucleus-nucleus potentials. In addition, TDHF calculations treat both reaction mechanisms and structure properties on the same footing. This is important for reactions with actinide targets which exhibit a strong quadrupole deformation.

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confidence: 99%

Deformed shell effects in Ca48+Bk249 quasifission fragments

2019

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“…In spite of the fact that the model describes rather well the MNT for many systems (see [4,5]), it fails to reproduce the experimental data for isospin-asymmetric combinations accurately enough. Particular example is the isotopic distributions of final projectile-like fragments (PLFs) obtained in the 40 Ca, 58 [12,13] had been taken into account in the calculations.…”

Section: Resultsmentioning

confidence: 93%

“…The model [4] has been improved by taking into account the equal sharing of the excitation energy and increased fluctuations of the charge asymmetry degree of freedom at the initial stage of a collision. It provides a better agreement of calculated and experimental isotopic distributions of products, especially for the transfer channels of a significant number of protons (> 5p).…”

Section: Resultsmentioning

confidence: 99%

“…One of such the models has been recently developed and has successfully described a bulk of experimental data obtained in the following MNT reactions: 136 Xe + 198 Pt, 208 Pb, 209 Bi; 160 Gd + 186 W; 208 Pb + 208 Pb; 238 U + 238 U, 248 Cm using the same set of the model parameters [4,5]. All these combinations are characterized by close values of neutron-to-proton ratio N/Z of projectiles and targets and can be called as isospin-symmetric ones.…”

Section: Introductionmentioning

confidence: 99%

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Role of charge equilibration in multinucleon transfer in damped collisions of heavy ions

Saiko¹,

Карпов²

2019

EPJ Web Conf.

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In this work the charge equilibration process has been analyzed within the Langevin-type dynamical approach. Its duration and energy dependence is discussed. We have analyzed the isotopic distributions of final products obtained in the isospin-asymmetric 58 Ni, 40 Ca + 208 Pb reactions. Comparison of 58 Ni, 64 Ni + 208 Pb systems have been done in order to analyze the final yields of neutron-rich heavy nuclides.

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“…The reliable theoretical predictions are therefore required to guide the current and future experiments at radioactive-ion beam facilities.Various theoretical models, including both the semiclassical and microscopic approaches, have been developed to describe the multinucleon transfer process. The semiclassical models, such as GRAZING [9], Complex Wentzel-Kramers-Brillouin (CWKB) [10], dinuclear system (DNS) [11][12][13][14][15][16][17][18], and the dynamical model based on Langevin-type equations of motion [19][20][21][22][23] have shown remarkable successes in reproducing the particular aspects of experimental data. However, the uncertainty of macroscopic parameters and the lack of microscopic origins restrict their predictive power and may obscure the underlying physical processes.…”

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confidence: 99%

Microscopic studies of production cross sections in multinucleon transfer reaction Ni58+Sn124

Guo

2019

Phys. Rev. C

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Background: Multinucleon transfer reaction at low-energy collisions is considered to be a promising method for the production of new exotic nuclei, which are difficult to be produced by other methods. The theoretical studies are required to provide reliable predictions for the experiments and promote the understanding of the microscopic mechanism in multinucleon transfer reactions. Purpose: We provide a predictive approach for production cross sections, and testify how and to what extent the microscopic approach works well in multinucleon transfer reaction. Methods: We employ the approach TDHF+GEMINI, which combines the microscopic time-dependent Hartree-Fock (TDHF) with the state-of-art statistical model GEMINI++, to take into account both the multinucleon transfer dynamics and the secondary deexcitation process. The properties of primary products in multinucleon transfer process, such as transfer probabilities and primary cross sections, are extracted from TDHF dynamics by using the particle-number projection method. Production cross sections for secondary products are evaluated by using the statistical model GEMINI++.Results: We investigate the influence of colliding energies and deformation orientations of target and projectile nuclei on multinucleon transfer dynamics in the reaction 58 Ni+ 124 Sn. More nucleons are observed to transfer in the tip collision as compared to the side collision. The production cross sections for secondary fragments with TDHF+GEMINI calculations well reproduce the experimental measurements at energies close to the Coulomb barrier. At sub-barrier energy, the theoretical results gradually deviate from the experimental data as the increase of the number of transferred neutrons, implying the limitations of a single mean-field approximation in TDHF approach. Possible origins for this discrepancy are discussed. The total cross sections integrated over all the neutron pickup channels are in good agreement with the experimental data for all the energies. We compare the production cross sections of TDHF+GEMINI calculations with those from GRAZING model, and find that our approach gives a quantitatively good description as the semiclassical model, although there is no adjustable parameters for the reaction dynamics in the microscopic TDHF method. Conclusions: The microscopic approach TDHF+GEMINI reasonably reproduces the experimental data at energies close to the Coulomb barrier and well accounts for the multinucleon transfer mechanism. The present studies clearly reveal the applicability of TDHF+GEMINI method in multinucleon transfer reactions, which thus deserves as a promising tool to predict the properties of new reactions. * luguo@ucas.ac.cn hance the yield of exotic nuclei for an appropriate projectiletarget combination. To produce the new unstable isotopes experimentally, the optimal incident energy and projectile-target combination should be chosen to have the highest product cross section for the desired isotope. The reliable theoretical predictions are therefore required to guide ...

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Modeling near-barrier collisions of heavy ions based on a Langevin-type approach

Cited by 143 publications

References 81 publications

Deformed shell effects in Ca48+Bk249 quasifission fragments

Deformed shell effects in Ca48+Bk249 quasifission fragments

Role of charge equilibration in multinucleon transfer in damped collisions of heavy ions

Microscopic studies of production cross sections in multinucleon transfer reaction Ni58+Sn124

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