The Experts below are selected from a list of 255234 Experts worldwide ranked by ideXlab platform
Francois Lechaftois - One of the best experts on this subject based on the ideXlab platform.
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gogny hartree fock bogolyubov plus quasiparticle random phase approximation predictions of the m 1 Strength Function and its impact on radiative neutron capture cross section
Physical Review C, 2016Co-Authors: Stephane Goriely, M Martini, Sophie Péru, Stephane Hilaire, I Deloncle, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1 \ensuremath{\gamma}$-ray Strength Function, obtained in the framework of the axially- symmetric-deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force, to the calculation of the $M1$ Strength Function. We compare our QRPA prediction of the $M1$ Strength with available experimental data and show that a relatively good agreement is obtained provided the Strength is shifted globally by about 2 MeV and increased by an empirical factor of 2. Predictions of the $M1$ Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed. Its impact on the radiative neutron capture cross section is also analyzed.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1$ $\gamma$-ray Strength Function obtained in the framework of the axially-symmetric deformed QRPA based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cut-off energy introduced in the 2-quasiparticle (2-$qp$) excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\sim$2 MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard 2-$qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to rather similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\gamma$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray Strength Function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cutoff energy introduced in the 2-quasiparticle $(2\ensuremath{-}qp)$ excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\ensuremath{\sim}2$ MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard $2\ensuremath{-}qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to somewhat similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\ensuremath{\gamma}$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
Stephane Goriely - One of the best experts on this subject based on the ideXlab platform.
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γ ray Strength Function for thallium isotopes relevant to the pb 205 tl 205 chronometry
Physical Review C, 2019Co-Authors: H Utsunomiya, Stephane Goriely, T Renstrom, G M Tveten, Takashi Ariizumi, D Filipescu, Jagjot Kaur, Yiuwing Lui, Wen Luo, S MiyamotoAbstract:Photoneutron cross sections were measured for $^{203}\mathrm{Tl}$ and $^{205}\mathrm{Tl}$ at energies between the one- and two-neutron thresholds using quasimonochromatic $\ensuremath{\gamma}$-ray beams produced in laser Compton scattering at the NewSUBARU synchrotron radiation facility. Our measurement results in cross sections significantly different from the previously reported bremsstrahlung experiment, leading to rather different giant dipole resonance (GDR) parameters, in particular to lower GDR peak energies and higher peak cross sections. The photoneutron data are used to constrain the $\ensuremath{\gamma}$-ray Strength Function on the basis of the Hartree-Fock-Bogolyubov plus quasiparticle random-phase approximation using the Gogny D1M interaction. Supplementing the experimentally constrained $\ensuremath{\gamma}$-ray Strength Function with the zero-limit $E1$ and $M1$ contributions for the de-excitation mode, we estimate the Maxwellian-averaged cross section for the s-process branching-point nucleus $^{204}\mathrm{Tl}$ in the context of the $^{205}\mathrm{Pb}\ensuremath{-}^{205}\mathrm{Tl}$ chronometry.
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gogny hfb qrpa dipole Strength Function and its application to radiative nucleon capture cross section
Physical Review C, 2018Co-Authors: Stephane Goriely, Sophie Péru, Stephane Hilaire, K SiejaAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole nuclear chart are of great interest for different applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1$ and $M1$ absorption $\ensuremath{\gamma}$-ray Strength Function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation (QRPA) based on the finite-range D1M Gogny force to the deexcitation Strength Function. To do so, shell-model calculations of the deexcitation dipole Strength Function are performed and their limit at low $\ensuremath{\gamma}$ energies used to complement phenomenologically the QRPA calculations. We compare our final prediction of the $E1$ and $M1$ Strength with available experimental data at low energies and show that a fairly good agreement is obtained. Predictions of the dipole Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed and compared with traditional Lorentzian-type prescriptions. Its impact on the total radiative width as well as radiative neutron and proton capture cross sections is studied.
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the gogny hfb qrpa dipole Strength Function and its application to radiative neutron capture cross section
Epj Web of Conferences, 2018Co-Authors: Stephane Goriely, Stephane Hilaire, Sophie PéruAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the E 1 and M 1 absorption γ -ray Strength Function obtained in the framework of the axially-symmetric deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force to the determination of the de-excitation Strength Function. To do so, shell-model calculations of the de-excitation dipole Strength Function as well as experimental data are considered to provide insight in the low-energy limit and to complement the QRPA estimate phenomenologically. We compare our final prediction of the E 1 and M 1 Strengths with available experimental data at low energies and show that a relatively good agreement can be obtained. Its impact on the average radiative width as well as radiative neutron capture cross section is discussed.
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gogny hartree fock bogolyubov plus quasiparticle random phase approximation predictions of the m 1 Strength Function and its impact on radiative neutron capture cross section
Physical Review C, 2016Co-Authors: Stephane Goriely, M Martini, Sophie Péru, Stephane Hilaire, I Deloncle, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1 \ensuremath{\gamma}$-ray Strength Function, obtained in the framework of the axially- symmetric-deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force, to the calculation of the $M1$ Strength Function. We compare our QRPA prediction of the $M1$ Strength with available experimental data and show that a relatively good agreement is obtained provided the Strength is shifted globally by about 2 MeV and increased by an empirical factor of 2. Predictions of the $M1$ Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed. Its impact on the radiative neutron capture cross section is also analyzed.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1$ $\gamma$-ray Strength Function obtained in the framework of the axially-symmetric deformed QRPA based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cut-off energy introduced in the 2-quasiparticle (2-$qp$) excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\sim$2 MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard 2-$qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to rather similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\gamma$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
Sophie Péru - One of the best experts on this subject based on the ideXlab platform.
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gogny hfb qrpa dipole Strength Function and its application to radiative nucleon capture cross section
Physical Review C, 2018Co-Authors: Stephane Goriely, Sophie Péru, Stephane Hilaire, K SiejaAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole nuclear chart are of great interest for different applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1$ and $M1$ absorption $\ensuremath{\gamma}$-ray Strength Function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation (QRPA) based on the finite-range D1M Gogny force to the deexcitation Strength Function. To do so, shell-model calculations of the deexcitation dipole Strength Function are performed and their limit at low $\ensuremath{\gamma}$ energies used to complement phenomenologically the QRPA calculations. We compare our final prediction of the $E1$ and $M1$ Strength with available experimental data at low energies and show that a fairly good agreement is obtained. Predictions of the dipole Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed and compared with traditional Lorentzian-type prescriptions. Its impact on the total radiative width as well as radiative neutron and proton capture cross sections is studied.
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the gogny hfb qrpa dipole Strength Function and its application to radiative neutron capture cross section
Epj Web of Conferences, 2018Co-Authors: Stephane Goriely, Stephane Hilaire, Sophie PéruAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the E 1 and M 1 absorption γ -ray Strength Function obtained in the framework of the axially-symmetric deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force to the determination of the de-excitation Strength Function. To do so, shell-model calculations of the de-excitation dipole Strength Function as well as experimental data are considered to provide insight in the low-energy limit and to complement the QRPA estimate phenomenologically. We compare our final prediction of the E 1 and M 1 Strengths with available experimental data at low energies and show that a relatively good agreement can be obtained. Its impact on the average radiative width as well as radiative neutron capture cross section is discussed.
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gogny hartree fock bogolyubov plus quasiparticle random phase approximation predictions of the m 1 Strength Function and its impact on radiative neutron capture cross section
Physical Review C, 2016Co-Authors: Stephane Goriely, M Martini, Sophie Péru, Stephane Hilaire, I Deloncle, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1 \ensuremath{\gamma}$-ray Strength Function, obtained in the framework of the axially- symmetric-deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force, to the calculation of the $M1$ Strength Function. We compare our QRPA prediction of the $M1$ Strength with available experimental data and show that a relatively good agreement is obtained provided the Strength is shifted globally by about 2 MeV and increased by an empirical factor of 2. Predictions of the $M1$ Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed. Its impact on the radiative neutron capture cross section is also analyzed.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1$ $\gamma$-ray Strength Function obtained in the framework of the axially-symmetric deformed QRPA based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cut-off energy introduced in the 2-quasiparticle (2-$qp$) excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\sim$2 MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard 2-$qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to rather similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\gamma$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray Strength Function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cutoff energy introduced in the 2-quasiparticle $(2\ensuremath{-}qp)$ excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\ensuremath{\sim}2$ MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard $2\ensuremath{-}qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to somewhat similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\ensuremath{\gamma}$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
Stephane Hilaire - One of the best experts on this subject based on the ideXlab platform.
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gogny hfb qrpa dipole Strength Function and its application to radiative nucleon capture cross section
Physical Review C, 2018Co-Authors: Stephane Goriely, Sophie Péru, Stephane Hilaire, K SiejaAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole nuclear chart are of great interest for different applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1$ and $M1$ absorption $\ensuremath{\gamma}$-ray Strength Function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation (QRPA) based on the finite-range D1M Gogny force to the deexcitation Strength Function. To do so, shell-model calculations of the deexcitation dipole Strength Function are performed and their limit at low $\ensuremath{\gamma}$ energies used to complement phenomenologically the QRPA calculations. We compare our final prediction of the $E1$ and $M1$ Strength with available experimental data at low energies and show that a fairly good agreement is obtained. Predictions of the dipole Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed and compared with traditional Lorentzian-type prescriptions. Its impact on the total radiative width as well as radiative neutron and proton capture cross sections is studied.
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the gogny hfb qrpa dipole Strength Function and its application to radiative neutron capture cross section
Epj Web of Conferences, 2018Co-Authors: Stephane Goriely, Stephane Hilaire, Sophie PéruAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the E 1 and M 1 absorption γ -ray Strength Function obtained in the framework of the axially-symmetric deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force to the determination of the de-excitation Strength Function. To do so, shell-model calculations of the de-excitation dipole Strength Function as well as experimental data are considered to provide insight in the low-energy limit and to complement the QRPA estimate phenomenologically. We compare our final prediction of the E 1 and M 1 Strengths with available experimental data at low energies and show that a relatively good agreement can be obtained. Its impact on the average radiative width as well as radiative neutron capture cross section is discussed.
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gogny hartree fock bogolyubov plus quasiparticle random phase approximation predictions of the m 1 Strength Function and its impact on radiative neutron capture cross section
Physical Review C, 2016Co-Authors: Stephane Goriely, M Martini, Sophie Péru, Stephane Hilaire, I Deloncle, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1 \ensuremath{\gamma}$-ray Strength Function, obtained in the framework of the axially- symmetric-deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force, to the calculation of the $M1$ Strength Function. We compare our QRPA prediction of the $M1$ Strength with available experimental data and show that a relatively good agreement is obtained provided the Strength is shifted globally by about 2 MeV and increased by an empirical factor of 2. Predictions of the $M1$ Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed. Its impact on the radiative neutron capture cross section is also analyzed.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1$ $\gamma$-ray Strength Function obtained in the framework of the axially-symmetric deformed QRPA based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cut-off energy introduced in the 2-quasiparticle (2-$qp$) excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\sim$2 MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard 2-$qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to rather similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\gamma$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray Strength Function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cutoff energy introduced in the 2-quasiparticle $(2\ensuremath{-}qp)$ excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\ensuremath{\sim}2$ MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard $2\ensuremath{-}qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to somewhat similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\ensuremath{\gamma}$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
M Martini - One of the best experts on this subject based on the ideXlab platform.
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low energy modification of the γ Strength Function of the odd even nucleus in 115
Physical Review C, 2016Co-Authors: M Versteegen, D Denispetit, V Meot, T Bonnet, M Comet, F Gobet, F Hannachi, M Tarisien, P Morel, M MartiniAbstract:Photoactivation yield measurements on $^{115}\mathrm{In}$ have been performed at the ELSA facility with Bremsstrahlung photon beams over a range of endpoint energies between 4.5 and 18 MeV. The measured photoexcitation yields of the $^{115m}\mathrm{In}$ metastable state are compared with calculated yields using cross sections obtained with different models of the photon Strength Function. It is shown that additional photon Strength with respect to the general Lorentzian model is needed at 8.1 MeV for the calculated yields to reproduce the data. The origin of this extra Strength is unclear, because it is compatible with additional Strength predicted in both $E1$ and $M1$ photon Strength distributions by quasiparticle random-phase approximation calculations using the Gogny D1S force.
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gogny hartree fock bogolyubov plus quasiparticle random phase approximation predictions of the m 1 Strength Function and its impact on radiative neutron capture cross section
Physical Review C, 2016Co-Authors: Stephane Goriely, M Martini, Sophie Péru, Stephane Hilaire, I Deloncle, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1 \ensuremath{\gamma}$-ray Strength Function, obtained in the framework of the axially- symmetric-deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force, to the calculation of the $M1$ Strength Function. We compare our QRPA prediction of the $M1$ Strength with available experimental data and show that a relatively good agreement is obtained provided the Strength is shifted globally by about 2 MeV and increased by an empirical factor of 2. Predictions of the $M1$ Strength Function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed. Its impact on the radiative neutron capture cross section is also analyzed.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1$ $\gamma$-ray Strength Function obtained in the framework of the axially-symmetric deformed QRPA based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cut-off energy introduced in the 2-quasiparticle (2-$qp$) excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\sim$2 MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard 2-$qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to rather similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\gamma$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.
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large scale deformed quasiparticle random phase approximation calculations of the γ ray Strength Function using the gogny force
Physical Review C, 2016Co-Authors: M Martini, Sophie Péru, Stephane Hilaire, Stephane Goriely, Francois LechaftoisAbstract:Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}$-ray Strength Function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation based on the finite-range Gogny force. This approach is applied to even-even nuclei, the Strength Function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cutoff energy introduced in the 2-quasiparticle $(2\ensuremath{-}qp)$ excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ Strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to overestimate the giant dipole energy by typically $\ensuremath{\sim}2$ MeV. Despite the microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some phenomenological corrections need to be included to take into account the effects beyond the standard $2\ensuremath{-}qp$ QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. For this purpose, three prescriptions of folding procedure are considered and adjusted to reproduce experimental photoabsorption data at best. All of them are shown to lead to somewhat similar predictions of the $E1$ Strength, both at low energies and for exotic neutron-rich nuclei. Predictions of $\ensuremath{\gamma}$-ray Strength Functions and Maxwellian-averaged neutron capture rates for the whole Sn isotopic chain are also discussed and compared with previous theoretical calculations.