Canonical-basis time-dependent Hartree-Fock-Bogoliubov theory and linear-response calculations

Ebata, Shuichiro; Nakatsukasa, Takashi; Inakura, Tsunenori; Yoshida, Kenichi; Hashimoto, Yukio; Yabana, Kazuhiro

doi:10.1103/physrevc.82.034306

Cited by 165 publications

(241 citation statements)

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“…Jz, 24.30.Cz, 27.60.+j The low-energy dipole states, often referred to as the pygmy dipole resonance (PDR), have attracted recent experimental [1][2][3][4][5][6] and theoretical interests [7][8][9][10][11][12] (see also the recent review [13] and references therein). It is also of significant astrophysical interest, since the low-energy dipole strengths close to the neutron threshold strongly affect the astrophysical r-process nucleosynthesis [14].…”

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confidence: 99%

Fragmentation of electric dipole strength inN=82isotones

Tohyama

Nakatsukasa

2012

Phys. Rev. C

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Fragmentation of the dipole strength in the N = 82 isotones 140 Ce, 142 Nd and 144 Sm is calculated using the second random-phase approximation (SRPA). In comparison with the result of the random-phase approximation (RPA), the SRPA provides the additional damping of the giant dipole resonance and the redistribution of the low-energy dipole strength. Properties of the low-energy dipole states are significantly changed by the coupling to two-particle-two-hole (2p2h) states, which are also sensitive to the correlation among the 2p2h states. Comparison with available experimental data shows a reasonable agreement for the low-energy E1 strength distribution.PACS numbers: 21.60. Jz, 24.30.Cz, 27.60.+j The low-energy dipole states, often referred to as the pygmy dipole resonance (PDR), have attracted recent experimental [1][2][3][4][5][6] and theoretical interests [7][8][9][10][11][12] (see also the recent review [13] and references therein). It is also of significant astrophysical interest, since the low-energy dipole strengths close to the neutron threshold strongly affect the astrophysical r-process nucleosynthesis [14].The quasiparticle random-phase approximation based on the Hartree-Fock-Bogoliubov ground state (HFB+QRPA) has been extensively used to study the PDR as well as the giant dipole resonances (GDR). Recent systematic calculations [15] for the Nd and Sm isotopes show that although the HFB+QRPA nicely reproduces characteristic features of the shape phase transition in the GDR, it fails to produce the low-energy dipole strengths at E x = 5.5 ∼ 8 MeV, observed in the N = 82 isotones, 142 Nd and 144 Sm [1,3]. The disagreement suggests that the coupling to complex configurations, such as multi-particle-multi-hole states, are required to study the PDR in these nuclei. In fact, the quasiparticle-phonon model (QPM), which takes into account coupling to multi-phonon states, successfully reproduces the low-energy dipole strengths in the N = 82 nuclei [2,4]. A similar approach based on the relativistic mean-field model has also been used to study the PDR in the tin and nickel isotopes [16]. These models assume the multi-phonon characters of the complex states and violate the Pauli principle. Thus, it is desirable to study properties of the PDR with a method complementary to these phonon-coupling approaches. In this work, we present studies for the dipole excitations in the N = 82 isotones, with the second random-phase approximation (SRPA) (Ref.[17] and references therein). The SRPA explicitly incorporates the two-particle-two-hole (2p2h) states instead of "two-phonon" states, and respects the Pauli principle in the 2p2h configurations. Recently, the low-energy dipole states in 40,48 Ca have been studied with the SRPA [18], which suggests that the coupling between one-particle-one-hole (1p1h) and 2p2h configurations enhances the electric dipole (E1) strength in the energy range from 5 to 10 MeV. We investigate whether a similar effect can be observed in the isotones of N = 82. Since there are many dipole states w...

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confidence: 99%

Fragmentation of electric dipole strength inN=82isotones

Tohyama

Nakatsukasa

2012

Phys. Rev. C

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“…In several studies, it has been shown that the BCS approximation is a good compromise to take into account pairing in the mean-field framework. In particular, comparisons to QRPA calculations show a good agreement with the BCS approximation for the small amplitude motion [6,7].…”

Section: Introductionmentioning

confidence: 64%

Microscopic description of²⁵⁸Fm fission dynamic with pairing

Scamps

Simenel

Lacroix

2016

EPJ Web of Conferences

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Fission dynamic remains a challenge for nuclear microscopic theories. In order to understand the dynamic of the last stage of the fission process, the time-dependent Hartree-Fock approach with BCS pairing is applied to the describe the fission of the 258 Fm. A good agreement is found for the one-body observables: the total kinetic energy and the average mass asymmetry. The non-physical dependence of two-body observables with the initial shape is discussed.

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“…[20,21]. These formulas are identical to the time dependent Hartree-Fock-Bogoliubov equations [22][23][24]. The symbol h γ denotes the Landau-Zener interaction, whileĒ γ and T γ are energy terms.…”

Section: The Landau-zener Effect and The Seniority Mixingmentioning

confidence: 91%

Odd-even effect dependence on the excitation energy in low energy fission

Mirea

2017

EPJ Web Conf.

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Abstract. An inversion of the odd-even effect was observed experimentally in cold fission: the odd-odd fragmentation yields are favored over the even-even ones for excitations energies of the fragments smaller than 4 MeV. This effect is linked to the important problem of quasiparticle excitations during the dynamical evolution of the nuclear system from its ground-state configuration up to scission. An explanation based on the Landau-Zener promotion mechanism generalized for superfluid systems is offered for the inversion of the odd-even effect. In principle, the even-even fission products cannot be produced at very low excitation energies due dynamical quasiparticle excitations produced in the avoided-level-crossing regions. These excitations are produced with a large probability when the nuclear system deforms slowly.

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Canonical-basis time-dependent Hartree-Fock-Bogoliubov theory and linear-response calculations

Cited by 165 publications

References 28 publications

Fragmentation of electric dipole strength inN=82isotones

Fragmentation of electric dipole strength inN=82isotones

Microscopic description of²⁵⁸Fm fission dynamic with pairing

Odd-even effect dependence on the excitation energy in low energy fission

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Canonical-basis time-dependent Hartree-Fock-Bogoliubov theory and linear-response calculations

Cited by 165 publications

References 28 publications

Fragmentation of electric dipole strength inN=82isotones

Fragmentation of electric dipole strength inN=82isotones

Microscopic description of258Fm fission dynamic with pairing

Odd-even effect dependence on the excitation energy in low energy fission

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Resources

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Microscopic description of²⁵⁸Fm fission dynamic with pairing