Dipole response of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow/><mml:mn>76</mml:mn></mml:msup></mml:math>Se above 4 MeV

Goddard, P.; Cooper, Nathan; Werner, V.; Rusev, G.; Stevenson, P. D.; Rios, Arnau; Bernards, C.; Chakraborty, Amit; Crider, B. P.; Glorius, J.; Ilieva, R. S.; Kelley, J. H.; Kwan, E.; Peters, E. E.; Pietralla, N.; Raut, R.; Romig, C.; Savran, D.; Schnorrenberger, L.; Smith, M. K.; Sonnabend, K.; Tonchev, A. P.; Tornow, W.; Yates, S. W.

doi:10.1103/physrevc.88.064308

Cited by 40 publications

(10 citation statements)

References 92 publications

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“…This parallels the procedure performed in Ref. [47]. In particular for the case of 54 Cr, stronger individual excitations as compared to 50 Cr and an accumulation of strength are visible in the vicinity of the neutron-separation energy of 9.7 MeV.…”

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confidence: 77%

Valence-shell dependence of the pygmy dipole resonance: E1 strength difference in Cr50,54

et al. 2019

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Background: The low-lying electric dipole strength provides insights on the parameters of the nuclear equation of state via its connection with the pygmy dipole resonance and nuclear neutron skin thickness.Purpose: Complement the systematic of the pygmy dipole resonance and first study its behavior across the N = 28 neutron shell closure.Methods: Photon-scattering cross sections of states of 50,54 Cr were measured up to an excitation energy of 9.7 MeV via the nuclear resonance fluorescence method using γ-ray beams from bremsstrahlung and Compton backscattering.Results: Transitions strengths, spin and parity quantum number and average branching ratios for 55 excited states, 44 of which were observed for the first time, were determined. The comparison between the total observed strengths of the isotopes 50,52,54 Cr shows a significant increase above the shell closure. Conclusions:The evolution of the pygmy dipole resonance is heavily influenced by the shell structure.

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confidence: 77%

Valence-shell dependence of the pygmy dipole resonance: E1 strength difference in Cr50,54

et al. 2019

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“…Various extensions to the Skyrme mean field have been proposed to explore more general spin-orbit forces [15,98,99], motivated by the Relativistic Mean Field. The simplest extension comes from allowing one extra parameter vary the isospin dependence as [100] [100] have been used for the study of fusion barriers [101], ternary fusion [102], in the study of equilibration within TDHF [103], and giant resonance calculations [104,105]. Of relevance for the case of heavy-ion reactions, Vo-Phuoc et al [101], compared the barrier energy as calculated with TDHF for the SLy4d [30] and UNEDF1 [106] Skyrme interactions.…”

Section: Spin-orbit Interactionsmentioning

confidence: 99%

Low-energy heavy-ion reactions and the Skyrme effective interaction

Stevenson

Barton

2019

Progress in Particle and Nuclear Physics

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The Skyrme effective interaction, with its multitude of parameterisations, along with its implementation using the static and time-dependent density functional (TDHF) formalism have allowed for a range of microscopic calculations of low-energy heavy-ion collisions. These calculations allow variation of the effective interaction along with an interpretation of the results of this variation informed by a comparison to experimental data. Initial progress in implementing TDHF for heavy-ion collisions necessarily used many approximations in the geometry or the interaction. Over the last decade or so, the implementations have overcome all restrictions, and studies have begun to be made where details of the effective interaction are being probed. This review surveys these studies in low energy heavy-ion reactions, finding significant effects on observables from the form of the spin-orbit interaction, the use of the tensor force, and the inclusion of time-odd terms in the density functional.Heavy-ion collisions combine the rich dynamics of a many-body out-of-equilibrium open quantum system with the complexities of the residual part of the strong interaction which leaks out of the small, but neither fundamental or point-like, nucleons, causing them to stick loosely together some of the time, and to fall apart at others. Understanding heavy-ion reactions across all energy scales is necessary to understand stellar nucleosynthesis [1], the synthesis of superheavy nuclei [2,3], the properties of nuclear matter [4][5][6], the QCD phase diagram [7,8] as well as the understanding of reaction mechanisms themselves [9][10][11][12][13].Among the theoretical techniques used to study heavy-ion reactions, methods based on timedependent Hartree-Fock have recently achieved the status of having sufficiently mature implementations free of limiting approximations, and running at a suitable speed, such that systematically varying the effective interaction in the calculations is possible. It is such studies that form the main subject of the present review. The practical implementations, using the Skyrme interaction, are in some sense parameter-free, in that one has a framework using an effective interaction fitted to ground state data and nuclear matter properties, with no further adjustment to dynamics. Structure and reaction effects are together determined self-consistently from the interaction, subject to the approximations of the mean-field and one gives no further adjustment. In another sense, the variation among the sets of available effective interactions are parameters of the calculations. We attempt to summarise here what has been learnt from exploring different Skyrme force parameterisations within low-energy heavy-ion reaction calculations.Overlapping this subject area are other recent review articles, to which the reader is referred: A review in which extensive coverage of theoretical approaches to dynamics of heavy-ion collisions in TDHF and its extensions is presented by Simenel and Umar [14]. This review extensively covers the...

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“…Dipole excitations at energies between 1.8 and 4 MeV were investigated in experiments at the former Stuttgart Dynamitron [20]. The dipole-strength distribution for energies up to S n is of particular interest because enhanced strength on the low-energy tail of the giant dipole resonance (GDR), often denoted as the "pygmy dipole resonance" (PDR) was found to be especially pronounced in 76 Se [21], 78 Se [22], nuclides with Z = 42 [23,24], N = 50 [25][26][27][28], around N = 82 [29][30][31][32][33][34][35][36], in 196 Pt [37], and in the doubly magic 208 Pb [38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Dipole strength ofTa181for the evaluation of theTa180stellar neutron capture rate

et al. 2014

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The photoabsorption cross section of 181 Ta up to the neutron-separation energy is deduced using bremsstrahlung produced with an electron beam of 9.6 MeV energy. The analysis of the measured γ -ray spectra includes the quasicontinuum of levels at high energy. Simulations of γ -ray cascades are performed to estimate intensities of inelastic transitions and branching ratios of the ground-state transitions. The resulting photoabsorption cross section shows enhanced dipole strength in the energy range from 5 to 8 MeV, which may be related to a pygmy dipole resonance. The results of the present experiment are compared with predictions of a quasiparticle-randomphase approximation in a deformed basis. A combination of the present experimental data and (γ,n) data is used as an input to the statistical code TALYS applied to calculate cross sections and reaction rates of photonuclear reactions that are important for the nucleosynthesis of 180 Ta.A. MAKINAGA et al. PHYSICAL REVIEW C 90, 044301 (2014)

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Dipole response of76Se above 4 MeV

Cited by 40 publications

References 92 publications

Valence-shell dependence of the pygmy dipole resonance: E1 strength difference in Cr50,54

Valence-shell dependence of the pygmy dipole resonance: E1 strength difference in Cr50,54

Low-energy heavy-ion reactions and the Skyrme effective interaction

Dipole strength ofTa181for the evaluation of theTa180stellar neutron capture rate

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