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A Schwenk - One of the best experts on this subject based on the ideXlab platform.
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nucleus dependent valence space approach to Nuclear Structure
Physical Review Letters, 2017Co-Authors: S R Stroberg, Robert Roth, Angelo Calci, H Hergert, J D Holt, S K Bogner, A SchwenkAbstract:We present a nucleus-dependent valence-space approach for calculating ground and excited states of nuclei, which generalizes the shell-model in-medium similarity renormalization group to an ensemble reference with fractionally filled orbitals. Because the ensemble is used only as a reference, and not to represent physical states, no symmetry restoration is required. This allows us to capture three-nucleon ($3N$) forces among valence nucleons with a valence-space Hamiltonian specifically targeted to each nucleus of interest. Predicted ground-state energies from carbon through nickel agree with results of other large-space ab initio methods, generally to the 1% level. In addition, we show that this new approach is required in order to obtain convergence for nuclei in the upper $p$ and $sd$ shells. Finally, we address the ${1}^{+}/{3}^{+}$ inversion problem in $^{22}\mathrm{Na}$ and $^{46}\mathrm{V}$. This approach extends the reach of ab initio Nuclear Structure calculations to essentially all light- and medium-mass nuclei.
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large scale Nuclear Structure calculations for spin dependent wimp scattering with chiral effective field theory currents
Physical Review D, 2013Co-Authors: Philipp Klos, Doron Gazit, Javier Fernandez Menendez, A SchwenkAbstract:We perform state-of-the-art large-scale shell-model calculations of the Structure factors for elastic spin-dependent WIMP scattering off $^{129,131}\mathrm{Xe}$, $^{127}\mathrm{I}$, $^{73}\mathrm{Ge}$, $^{19}\mathrm{F}$, $^{23}\mathrm{Na}$, $^{27}\mathrm{Al}$, and $^{29}\mathrm{Si}$. This comprehensive survey covers the nonzero-spin nuclei relevant to direct dark matter detection. We include a pedagogical presentation of the formalism necessary to describe elastic and inelastic WIMP-nucleus scattering. The valence spaces and Nuclear interactions employed have been previously used in Nuclear Structure calculations for these mass regions and yield a good spectroscopic description of these isotopes. We use spin-dependent WIMP-nucleus currents based on chiral effective field theory at the one-body level and including the leading long-range two-body currents due to pion exchange, which are predicted in chiral effective field theory. Results for all Structure factors are provided with theoretical error bands due to the Nuclear uncertainties of WIMP currents in nuclei.
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large scale Nuclear Structure calculations for spin dependent wimp scattering with chiral effective field theory currents
Physical Review D, 2013Co-Authors: Philipp Klos, J Menendez, Doron Gazit, A SchwenkAbstract:We perform state-of-the-art large-scale shell-model calculations of the Structure factors for elastic spin-dependent WIMP scattering off 129,131Xe, 127I, 73Ge, 19F, 23Na, 27Al, and 29Si. This comprehensive survey covers the non-zero-spin nuclei relevant to direct dark matter detection. We include a pedagogical presentation of the formalism necessary to describe elastic and inelastic WIMP-nucleus scattering. The valence spaces and Nuclear interactions employed have been previously used in Nuclear Structure calculations for these mass regions and yield a good spectroscopic description of these isotopes. We use spin-dependent WIMP-nucleus currents based on chiral effective field theory (EFT) at the one-body level and including the leading long-range two-body currents due to pion exchange, which are predicted in chiral EFT. Results for all Structure factors are provided with theoretical error bands due to the Nuclear uncertainties of WIMP currents in nuclei.
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from low momentum interactions to Nuclear Structure
Progress in Particle and Nuclear Physics, 2010Co-Authors: S K Bogner, A Schwenk, R J FurnstahlAbstract:We present an overview of low-momentum two-nucleon and many-body interactions and their use in calculations of nuclei and infinite matter. The softening of phenomenological and effective field theory (EFT) potentials by renormalization group (RG) transformations that decouple low and high momenta leads to greatly enhanced convergence in few- and many-body systems while maintaining a decreasing hierarchy of many-body forces. This review surveys the RG-based technology and results, discusses the connections to chiral EFT, and clarifies various misconceptions.
Boiano C. - One of the best experts on this subject based on the ideXlab platform.
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Testing ab initio Nuclear Structure in neutron-rich nuclei: Lifetime measurements of second 2+ state in 16C and 20O
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Crespi F., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich 20O, tau(2+_2 ) = 150(+80-30) fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds femtoseconds range, by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction 18O (7.0 MeV/u) + 181Ta. The requested sensitivity could only be reached owing to the excellent performances of the AGATA gamma-tracking array, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for 20O, and with the no-core shell model for 16C. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetimes measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense ISOL-type beams become available
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Testing ab initio Nuclear Structure in neutron-rich nuclei: lifetime measurements of second 2+ states in 16C and 20O
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Crespi F. C. L., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich 20O, tau(2+_2 ) = 150(+80-30) fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds femtoseconds range, by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction 18O (7.0 MeV/u) + 181Ta. The requested sensitivity could only be reached owing to the excellent performances of the AGATA gamma-tracking array, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for 20O, and with the no-core shell model for 16C. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetimes measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense ISOL-type beams become available
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Testing $ab initio$ Nuclear Structure in neutron-rich nuclei: lifetime measurements of second 2$^+$ states in $^{16}$C and $^{20}$O
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Crespi F.c.l., Boiano C.Abstract:International audienceTo test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich O20,τ(22+)=150−30+80fs, and an estimate for the lifetime of the second 2+ state in C16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted γ-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O18(7.0MeV/u)+Ta181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced γ-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O20 and with the no-core shell model for C16. The present measurement shows the power of electromagnetic observables, determined with high-precision γ spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available
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Testing ab initio Nuclear Structure in neutron-rich nuclei: Lifetime measurements of second 2+ state in C 16 and O 20
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Crespi F. C. L., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich O20,τ(22+)=150-30+80fs, and an estimate for the lifetime of the second 2+ state in C16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted γ-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O18(7.0MeV/u)+Ta181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced γ-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two-and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O20 and with the no-core shell model for C16. The present measurement shows the power of electromagnetic observables, determined with high-precision γ spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available
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Testing ab initio Nuclear Structure in neutron-rich nuclei : Lifetime measurements of second 2(+) state in C-16 and O-20
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Crespi F. C. L., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2(+) state in neutron-rich O-20, tau(2(2)(+)) = 150(-30)(+80) fs, and an estimate for the lifetime of the second 2(+) state in C-16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O-18 (7.0 MeV/u) + Ta-181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced gamma-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O-20 and with the no-core shell model for C-16. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available
I. D. Moore - One of the best experts on this subject based on the ideXlab platform.
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Measurement of an unusually large magnetic octupole moment in $^{45}$Sc challenges state-of-the-art Nuclear-Structure theory
arXiv: Nuclear Experiment, 2020Co-Authors: R. P. De Groote, J. Moreno, Jacek Dobaczewski, I. D. Moore, Mikael Reponen, B. K. Sahoo, C YuanAbstract:We measure the hyperfine $C$-constant of the $3d4s^2 ~^2D_{5/2}$ atomic state in $^{45}$Sc: $C=-0.25(12)$\,kHz. High-precision atomic calculations of the hyperfine Structure of the $3d4s^2 ~^2D_{5/2}$ state and second-order corrections are performed to infer the Nuclear magnetic octupole moment $\Omega = 1.6(8) \mu_N b$. With a single valence proton outside of the doubly-magic calcium core, this element is ideally suited for an in-depth study of the many intriguing Nuclear Structure phenomena observed within the neighboring isotopes of calcium. We compare $\Omega$ to shell-model calculations, and find that they cannot reproduce the experimental value of $\Omega$ for $^{45}$Sc. We furthermore explore the use of Density Functional Theory for evaluating $\Omega$, and obtain values in line with the shell-model calculations. This work provides a crucial step in guiding future measurements of this fundamental quantity on radioactive scandium isotopes and will hopefully motivate a renewed experimental and theoretical interest.
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measurement of an unusually large magnetic octupole moment in 45 sc challenges state of the art Nuclear Structure theory
arXiv: Nuclear Experiment, 2020Co-Authors: R. P. De Groote, J. Moreno, Jacek Dobaczewski, I. D. Moore, Mikael Reponen, B. K. Sahoo, C YuanAbstract:We measure the hyperfine $C$-constant of the $3d4s^2 ~^2D_{5/2}$ atomic state in $^{45}$Sc: $C=-0.25(12)$\,kHz. High-precision atomic calculations of the hyperfine Structure of the $3d4s^2 ~^2D_{5/2}$ state and second-order corrections are performed to infer the Nuclear magnetic octupole moment $\Omega = 1.6(8) \mu_N b$. With a single valence proton outside of the doubly-magic calcium core, this element is ideally suited for an in-depth study of the many intriguing Nuclear Structure phenomena observed within the neighboring isotopes of calcium. We compare $\Omega$ to shell-model calculations, and find that they cannot reproduce the experimental value of $\Omega$ for $^{45}$Sc. We furthermore explore the use of Density Functional Theory for evaluating $\Omega$, and obtain values in line with the shell-model calculations. This work provides a crucial step in guiding future measurements of this fundamental quantity on radioactive scandium isotopes and will hopefully motivate a renewed experimental and theoretical interest.
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laser spectroscopy for Nuclear Structure physics
Progress in Particle and Nuclear Physics, 2016Co-Authors: P Campbell, I. D. Moore, M R PearsonAbstract:Abstract High-resolution laser spectroscopy is an established powerful tool in the study of Nuclear shape, size and multipole moments. Measurements of the hyperfine Structures and isotope shifts in the atomic spectra of radioactive nuclei provide unique insight into the evolution of the Nuclear macroscopic shape and microscopic Structure. These measurements can be made with high precision and high sensitivity and applied directly on-line at radioactive Nuclear beam facilities. Recent measurements, advances at facilities and the future direction of the field are reviewed. A summary of experimental data is presented.
Philipp Klos - One of the best experts on this subject based on the ideXlab platform.
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large scale Nuclear Structure calculations for spin dependent wimp scattering with chiral effective field theory currents
Physical Review D, 2013Co-Authors: Philipp Klos, Doron Gazit, Javier Fernandez Menendez, A SchwenkAbstract:We perform state-of-the-art large-scale shell-model calculations of the Structure factors for elastic spin-dependent WIMP scattering off $^{129,131}\mathrm{Xe}$, $^{127}\mathrm{I}$, $^{73}\mathrm{Ge}$, $^{19}\mathrm{F}$, $^{23}\mathrm{Na}$, $^{27}\mathrm{Al}$, and $^{29}\mathrm{Si}$. This comprehensive survey covers the nonzero-spin nuclei relevant to direct dark matter detection. We include a pedagogical presentation of the formalism necessary to describe elastic and inelastic WIMP-nucleus scattering. The valence spaces and Nuclear interactions employed have been previously used in Nuclear Structure calculations for these mass regions and yield a good spectroscopic description of these isotopes. We use spin-dependent WIMP-nucleus currents based on chiral effective field theory at the one-body level and including the leading long-range two-body currents due to pion exchange, which are predicted in chiral effective field theory. Results for all Structure factors are provided with theoretical error bands due to the Nuclear uncertainties of WIMP currents in nuclei.
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large scale Nuclear Structure calculations for spin dependent wimp scattering with chiral effective field theory currents
Physical Review D, 2013Co-Authors: Philipp Klos, J Menendez, Doron Gazit, A SchwenkAbstract:We perform state-of-the-art large-scale shell-model calculations of the Structure factors for elastic spin-dependent WIMP scattering off 129,131Xe, 127I, 73Ge, 19F, 23Na, 27Al, and 29Si. This comprehensive survey covers the non-zero-spin nuclei relevant to direct dark matter detection. We include a pedagogical presentation of the formalism necessary to describe elastic and inelastic WIMP-nucleus scattering. The valence spaces and Nuclear interactions employed have been previously used in Nuclear Structure calculations for these mass regions and yield a good spectroscopic description of these isotopes. We use spin-dependent WIMP-nucleus currents based on chiral effective field theory (EFT) at the one-body level and including the leading long-range two-body currents due to pion exchange, which are predicted in chiral EFT. Results for all Structure factors are provided with theoretical error bands due to the Nuclear uncertainties of WIMP currents in nuclei.
Ciemala M. - One of the best experts on this subject based on the ideXlab platform.
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Testing ab initio Nuclear Structure in neutron-rich nuclei: Lifetime measurements of second 2+ state in 16C and 20O
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Crespi F., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich 20O, tau(2+_2 ) = 150(+80-30) fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds femtoseconds range, by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction 18O (7.0 MeV/u) + 181Ta. The requested sensitivity could only be reached owing to the excellent performances of the AGATA gamma-tracking array, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for 20O, and with the no-core shell model for 16C. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetimes measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense ISOL-type beams become available
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Testing ab initio Nuclear Structure in neutron-rich nuclei: lifetime measurements of second 2+ states in 16C and 20O
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Crespi F. C. L., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich 20O, tau(2+_2 ) = 150(+80-30) fs, and an estimate for the lifetime of the second 2+ state in 16C have been obtained, for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds femtoseconds range, by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction 18O (7.0 MeV/u) + 181Ta. The requested sensitivity could only be reached owing to the excellent performances of the AGATA gamma-tracking array, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for 20O, and with the no-core shell model for 16C. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetimes measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense ISOL-type beams become available
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Testing $ab initio$ Nuclear Structure in neutron-rich nuclei: lifetime measurements of second 2$^+$ states in $^{16}$C and $^{20}$O
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Crespi F.c.l., Boiano C.Abstract:International audienceTo test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich O20,τ(22+)=150−30+80fs, and an estimate for the lifetime of the second 2+ state in C16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted γ-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O18(7.0MeV/u)+Ta181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced γ-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O20 and with the no-core shell model for C16. The present measurement shows the power of electromagnetic observables, determined with high-precision γ spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available
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Testing ab initio Nuclear Structure in neutron-rich nuclei: Lifetime measurements of second 2+ state in C 16 and O 20
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Crespi F. C. L., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2+ state in neutron-rich O20,τ(22+)=150-30+80fs, and an estimate for the lifetime of the second 2+ state in C16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted γ-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O18(7.0MeV/u)+Ta181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced γ-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two-and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O20 and with the no-core shell model for C16. The present measurement shows the power of electromagnetic observables, determined with high-precision γ spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available
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Testing ab initio Nuclear Structure in neutron-rich nuclei : Lifetime measurements of second 2(+) state in C-16 and O-20
'American Physical Society (APS)', 2020Co-Authors: Ciemala M., Ziliani S., Crespi F. C. L., Leoni S., Fornal B., Maj A., Bednarczyk P., Benzoni G., Bracco A., Boiano C.Abstract:To test the predictive power of ab initio Nuclear Structure theory, the lifetime of the second 2(+) state in neutron-rich O-20, tau(2(2)(+)) = 150(-30)(+80) fs, and an estimate for the lifetime of the second 2(+) state in C-16 have been obtained for the first time. The results were achieved via a novel Monte Carlo technique that allowed us to measure Nuclear state lifetimes in the tens-to-hundreds of femtoseconds range by analyzing the Doppler-shifted gamma-transition line shapes of products of low-energy transfer and deep-inelastic processes in the reaction O-18 (7.0 MeV/u) + Ta-181. The requested sensitivity could only be reached owing to the excellent performances of the Advanced gamma-Tracking Array AGATA, coupled to the PARIS scintillator array and to the VAMOS++ magnetic spectrometer. The experimental lifetimes agree with predictions of ab initio calculations using two- and three-nucleon interactions, obtained with the valence-space in-medium similarity renormalization group for O-20 and with the no-core shell model for C-16. The present measurement shows the power of electromagnetic observables, determined with high-precision gamma spectroscopy, to assess the quality of first-principles Nuclear Structure calculations, complementing common benchmarks based on Nuclear energies. The proposed experimental approach will be essential for short lifetime measurements in unexplored regions of the Nuclear chart, including r-process nuclei, when intense beams, produced by Isotope Separation On-Line (ISOL) techniques, become available
