M1 strength functions from large-scale shell-model calculations and their effect on astrophysical neutron capture cross-sections

Loens, H. P.; Langanke, K.; Martı́nez-Pinedo, G.; Sieja, K.

doi:10.1140/epja/i2012-12034-5

Cited by 40 publications

(30 citation statements)

References 47 publications

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“…Specifically, M1 spin-flip excitations are analog of Gamow-Teller (GT) transitions, meaning that, at the operator level, the dominant M1 isovector component is the synonym to the zeroth component of GT transitions, and can serve as probe for calculations of inelastic neutrinonucleus cross section [8,9]. This process is hard to measure but it is essential in supernova physics, as well as in the r-process nucleosynthesis calculations [6,7,10,11]. The isovector spin-flip M1 response is also relevant for applications related to the design of nuclear reactors [12], for the understanding of single-particle properties, spinorbit interaction, and shell closures from stable nuclei toward limits of stability [13][14][15][16][17], as well as for the resolving the problem of quenching of the spin-isopin response in nuclei that is necessary for reliable description of double beta decay matrix elements [18].…”

Section: Introductionmentioning

confidence: 99%

Magnetic dipole excitations based on the relativistic nuclear energy density functional

et al. 2020

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Magnetic dipole (M1) excitations build not only a fundamental mode of nucleonic transitions, but they are also relevant for nuclear astrophysics applications. We have established a theory framework for description of M1 transitions based on the relativistic nuclear energy density functional. For this purpose the relativistic quasiparticle random phase approximation (RQRPA) is established using density dependent point coupling interaction DD-PC1, supplemented with the isovectorpseudovector interaction channel in order to study unnatural parity transitions. The introduced framework has been validated using the M1 sum rule for core-plus-two-nucleon systems, and employed in studies of the spin, orbital, isoscalar and isovector M1 transition strengths in magic nuclei 48 Ca and 208 Pb, and open shell nuclei 42 Ca and 50 Ti. In these systems, the isovector spin-flip M1 transition is dominant, mainly between one or two spin-orbit partner states. It is shown that pairing correlations have a significant impact on the centroid energy and major peak position of the M1 mode. The M1 excitations could provide an additional constraint to improve nuclear energy density functionals in the future studies.I.

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Section: Introductionmentioning

confidence: 99%

Magnetic dipole excitations based on the relativistic nuclear energy density functional

et al. 2020

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“…Radiative neutron capture is one of the basic processes for the synthesis of heavy elements in stellar environments and relevant for next-generation nuclear technologies. It has been shown, that the dipole-strength distribution in the energy region below the neutron-separation energy has a direct influence on neutron-capture rates [2,3]. Modifications of the dipole strength at low excitation energy considerably change calculated relative abundances of several isotopes in the solar system [4].…”

Section: Introductionmentioning

confidence: 99%

Magnetic dipole strength inXe128andXe134in the spin-flip resonance region

et al. 2014

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The magnetic dipole strength in the energy region of the spin-flip resonance has been investigated in 128 Xe and 134 Xe using quasi-monoenergetic and linearly polarized γ-ray beams at the HIγS facility in Durham, NC, USA. Absorption cross sections were deduced for the magnetic and electric and dipole strength distributions separately for various intervals of excitation energy, including the strength of states in the unresolved quasi-continuum. The magnetic dipole strength distributions show structures resembling a resonance in the spin-flip region around an excitation energy of 8 MeV. The electric dipole strength distributions obtained from the present experiments are in agreement with the ones deduced from an earlier experiment using broad-band bremsstrahlung instead of a quasi-monoenergetic beam. The experimental magnetic and electric dipole strength distributions are compared with phenomenological approximations and with predictions of a quasiparticle-randomphase-approximation in a deformed basis.

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“…Thus, the IV-M1 transition is expected as a probe into the spinisospin properties of nuclei and its relevant interactions [1][2][3]. This process also plays a role in the determination of neutron-capture rates, of significance for the r-process nucleosynthesis [4][5][6]. For the description of M1 transitions, main contributions stem from the spinorbit (SO) splitting as well as the M1-residual interaction.…”

Section: Introductionmentioning

confidence: 99%

Symmetry breaking of Gamow-Teller and magnetic-dipole transitions and its restoration in calcium isotopes

Oishi,

Ravlic,

Paar

2022

Preprint

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Nuclear magnetic-dipole (M1) and Gamow-Teller (GT) transitions provide insight into the spinisospin properties of atomic nuclei. By considering them as unified spin-isospin transitions, the M1/GT transition strengths and excitation energies are subject to isobaric-analog symmetry. The excitation properties associated to the M1/GT symmetry need to be clarified within consistent theoretical approach. In this work, the relationship between the M1 and GT transitions in Ca isotopes is investigated in a unified framework based on the relativistic energy-density functional (REDF) with point-coupling interactions, using the relativistic quasi-particle random-phase approximation (RQRPA). It is shown that the isovector-pseudovector (IV-PV) residual interaction affects these transitions. The symmetry of M1 and giant-GT transitions can be disrupted by this interaction in closed-shell nuclei. In open-shell Ca isotopes, the proton-neutron pairing in the residual RQRPA interaction also plays a role in GT transitions. Due to the interplay between these interactions, the M1/GT symmetry can be restored especially in the 42 Ca nucleus, i.e., the giant-GT strength can become comparable to that of the M1 mode in terms of the unified spin-isospin transitions by fixing the PN-pairing strength so as to reproduce the experimental low-lying GT-excitation energies. The mirror symmetry of both M1 and GT transitions is also demonstrated for open-shell mirror partners, 42 Ca and 42 Ti. Further improvements are required to achieve more accurate simultaneous reproduction of M1 and GT-transition energies in the REDF framework.

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M1 strength functions from large-scale shell-model calculations and their effect on astrophysical neutron capture cross-sections

Cited by 40 publications

References 47 publications

Magnetic dipole excitations based on the relativistic nuclear energy density functional

Magnetic dipole excitations based on the relativistic nuclear energy density functional

Magnetic dipole strength inXe128andXe134in the spin-flip resonance region

Symmetry breaking of Gamow-Teller and magnetic-dipole transitions and its restoration in calcium isotopes

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