Pygmy dipole resonance in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>208</mml:mn></mml:msup></mml:math>Pb

Poltoratska, I.; Neumann-Cosel, P. von; Tamii, A.; Adachi, T.; Bertulani, C. A.; Carter, J.; Dozono, M.; Fujita, H.; Fujita, K.; Fujita, Y.; Hatanaka, K.; Itoh, Masatoshi; Kawabata, T.; Kalmykov, Y.; Krumbholz, A. M.; Литвинова, Елена; Matsubara, Hiroaki; Nakanishi, K.; Neveling, R.; Okamura, H.; Ong, H. J.; Oezel-Tashenov, B.; Ponomarev, V. Yu.; Richter, A.; Rubio, B.; Sakaguchi, H.; Sakemi, Y.; Sasamoto, Y.; Shimbara, Y.; Shimizu, Ỹ.; Smit, F. D.; Suzuki, Tomokazu; Tameshige, Y.; Wambach, J.; Yosoi, M.; Zenihiro, J.

doi:10.1103/physrevc.85.041304

Cited by 100 publications

(150 citation statements)

References 41 publications

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“…Details of the present QPM calculations are discussed in Refs. [15,17,35]. Results of the wavelet analysis of QPM and RTBA E1 strength distributions are presented in Figs.…”

Section: B Application To the Ivgdr In 208 Pbmentioning

confidence: 99%

“…Refs. [15,17]). However, the need to disentangle the E1 cross section from other contributions can only be achieved for larger energy bins, where the information on the fine structure is partially lost.…”

Section: B Application To the Ivgdr In 208 Pbmentioning

confidence: 99%

“…At these extreme forward angles E1 Coulomb excitation dominates the cross sections and nuclear transitions are suppressed with the exception of the isovector spin-flip M 1 resonance. The excitation energy region below 9 MeV, where the spin-M 1 mode is located and contributes significantly to the cross sections [17,31], is thus excluded. In order to search for characteristic scales it is helpful to construct the power spectrum of the signal, i.e.…”

Section: B Application To the Ivgdr In 208 Pbmentioning

confidence: 99%

“…Different from the MDA in the low-energy region discussed in Ref. [17], the main contributions are from excitation of the ISGQR (dotted line) and a phenomenological part (dashed line) including quasifree reactions and the tail of giant resonances centered at higher excitation energies. In any case, the contributions under the IVGDR peak are small justifying the assumption that they do not influence the fluctuations visible in the data.…”

Section: Introductionmentioning

confidence: 99%

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Fine structure of the isovector giant dipole resonance inPb208: Characteristic scales and level densities

et al. 2014

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Background: The electric isovector giant dipole resonance (IVGDR) in208 Pb has been measured with high energy resolution with the (p, p ) reaction under extreme forward angles [A. Tamii et al., Phys. Rev. Lett. 107, 062502 (2011)] and shows considerable fine structure.Purpose: The aim of the present work is to extract scales characterizing the observed fine structure and to relate them to dominant decay mechanisms of giant resonances. Furthermore, the level density of J π = 1 − states is determined in the energy region of the IVGDR.Methods: Characteristic scales are extracted from the spectra with a wavelet analysis based on continuous wavelet transforms.Comparison with corresponding analyses of B(E1) strength distributions from microscopic model calculations in the framework of the quasiparticle phonon model and the relativistic random phase approximation allow to identify giant resonance decay mechanisms responsible for the fine structure. The level density of 1 − states is related to local fluctuations of the cross sections in the energy region of the IVGDR, where contributions from states with other spin-parities can be neglected. The magnitude of the fluctuations is determined by the autocorrelation function.Results: Scales in the fine structure of the IVGDR in 208 Pb are found at 80, 130, 220, 430, 640, 960 keV, and at 1.75 MeV. The values of the most prominent scales can be reasonably well reproduced by the microscopic calculations although they generally yield a smaller number of scales.. The inclusion of complex configurations in the calculations changes the E1 strength distributions but the impact on the wavelet power spectra and characteristic scales is limited. The level density of 1 − states is extracted in the excitation energy range 9 − 12.5 MeV and compared to a variety of phenomenological and microscopic models. Conclusions:In both models the major scales are already present at the one-particle one-hole level indicating Landau damping as a dominant mechanism responsible for the fine structure of the IVGDR in contrast to the isoscalar giant quadrupole resonance, where fine structure arises from the coupling to low-lying surface vibrations. The back-shifted Fermi gas model parameterization of Rauscher et al., Phys. Rev. C 56, 1613 describes the level-density data well, while other phenomeological and microscopic approaches fail to reproduce absolute values or the energy dependence or both.

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“…Details of the present QPM calculations are discussed in Refs. [15,17,35]. Results of the wavelet analysis of QPM and RTBA E1 strength distributions are presented in Figs.…”

Section: B Application To the Ivgdr In 208 Pbmentioning

confidence: 99%

Section: B Application To the Ivgdr In 208 Pbmentioning

confidence: 99%

Section: B Application To the Ivgdr In 208 Pbmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fine structure of the isovector giant dipole resonance inPb208: Characteristic scales and level densities

et al. 2014

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“…In stable nuclei, dense discrete spectra of dipole states were detected in (γ, γ ) [3][4][5][6][7][8][9] and in (α, α γ) experiments [10][11][12]. Moreover, fairly complete dipole spectra below and above the neutron decay threshold were produced with great accuracy through inelastic proton scattering experiments [13,14].…”

Section: Introductionmentioning

confidence: 93%

Dipole response in neutron-rich nuclei within self-consistent approaches using realistic potentials

Iudice

Knapp

Veselý

et al. 2015

EPJ Web of Conferences

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Abstract.A nucleon-nucleon chiral potential with a corrective density dependent term simulating a three-body force is used in a self-consistent calculation of the dipole strength distribution in neutron-rich nuclei, with special attention to the low-lying spectra associated to the pygmy resonance. A Hartree-Fock-Bogoliubov basis is generated and adopted in Tamm-Dancoff and random-phase approximations and, then, in an equation of motion approach which includes a basis of two-phonon states. The direct use of the mentioned chiral potential improves the description of both giant and pygmy dipole modes with respect to other realistic interactions. Moreover, the inclusion of the two-phonon states induces a pronounced fragmentation of the giant resonance and enhances the density of the low-lying levels in the pygmy region in agreement with recent experiments.

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Excited Nuclear States for Pb-208 (Lead)

Sukhoruchkin¹,

Soroko²

2016

Supplement to I/25 a-G

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Pygmy dipole resonance in208Pb

Cited by 100 publications

References 41 publications

Fine structure of the isovector giant dipole resonance inPb208: Characteristic scales and level densities

Fine structure of the isovector giant dipole resonance inPb208: Characteristic scales and level densities

Dipole response in neutron-rich nuclei within self-consistent approaches using realistic potentials

Excited Nuclear States for Pb-208 (Lead)

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