Exploring<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>s</mml:mi><mml:mi>d</mml:mi></mml:mrow></mml:math>-shell nuclei from two- and three-nucleon interactions with realistic saturation properties

Simonis, J.; Hebeler, K.; Holt, J. D.; Menéndez, J. Fernández; Schwenk, A.

doi:10.1103/physrevc.93.011302

Cited by 107 publications

(183 citation statements)

References 67 publications

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“…Without these initial 3N forces, the spectra of 25,26 F are much too compressed, but with their addition, the IM-SRG spectra are in reasonable agreement with predictions from phenomenology [23]. More generally, 3N forces are necessary to reproduce properties of exotic nuclei near oxygen and calcium [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. In this work, we extend this approach to the ensemble normal-ordering procedure outlined in Ref.…”

Section: Modelsmentioning

confidence: 82%

Effective proton-neutron interaction near the drip line from unbound states in F25,26

Vandebrouck¹,

Lepailleur²,

Sorlin³

et al. 2017

Phys. Rev. C

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Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The 26 F nucleus, composed of a deeply bound π 0d 5/2 proton and an unbound ν0d 3/2 neutron on top of an 24 O core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a J π = 1 1 + − 4 1 + multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The J π = 1 1 + , 2 1 + , 4 1 + bound states have been determined, and only a clear identification of the J π = 3 1 + is missing. Purpose: We wish to complete the study of the J π = 1 1 + − 4 1 + multiplet in 26 F, by studying the energy and width of the J π = 3 1 + unbound state. The method was first validated by the study of unbound states in 25 F, for which resonances were already observed in a previous experiment. Method: Radioactive beams of 26 Ne and 27 Ne, produced at about 440A MeV by the fragment separator at the GSI facility were used to populate unbound states in 25 F and 26 F via one-proton knockout reactions on a CH 2 target, located at the object focal point of the R 3 B/LAND setup. The detection of emitted γ rays and neutrons, added to the reconstruction of the momentum vector of the A − 1 nuclei, allowed the determination of the energy of three unbound states in 25 F and two in 26 F. Results: Based on its width and decay properties, the first unbound state in 25 F, at the relative energy of 49(9) keV, is proposed to be a J π = 1/2 − arising from a p 1/2 proton-hole state. In 26 F, the first resonance at 323(33) keV is proposed to be the J π = 3 1 + member of the J π = 1 1 + − 4 1 + multiplet. Energies of observed states in 25,26 F have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton-neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of 26 F.

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Section: Modelsmentioning

confidence: 82%

Effective proton-neutron interaction near the drip line from unbound states in F25,26

Vandebrouck¹,

Lepailleur²,

Sorlin³

et al. 2017

Phys. Rev. C

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“…In particular, we compare results obtained with the 1.8/2.0(EM), the N 2 LO sat and the NN+3N(lnl) interactions. The 1.8/2.0(EM) interaction [48][49][50] combines an SRG-evolved [51] next-to-next-to-next-to-leading order (N3LO) chiral NN potential [52] with a next-tonext-to-leading order (N2LO) non-renormalized chiral 3N force. The N 2 LO sat interaction [53] has NN and 3N terms fitted simultaneously to properties of A = 2, 3, 4 nuclei as well as to selected systems up to 24 O.…”

Section: T a N -M P E T T I T A N -M R -T O F -M S M E ( T I T A N -mentioning

confidence: 99%

Dawning of the N=32 Shell Closure Seen through Precision Mass Measurements of Neutron-Rich Titanium Isotopes

Leistenschneider¹,

Reiter²,

Andrés³

et al. 2018

Phys. Rev. Lett.

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104

129

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A precision mass investigation of the neutron-rich titanium isotopes 51−55 Ti was performed at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the N = 32 shell closure and the overall uncertainties of the 52−55 Ti mass values were significantly reduced. Our results conclusively establish the existence of weak shell effect at N = 32, narrowing down the abrupt onset of this shell closure. Our data were compared with state-of-the-art ab initio shell model calculations which, despite very successfully describing where the N = 32 shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements also represent the first scientific results of TITAN using the newly commissioned Multiple-Reflection Time-of-Flight Mass Spectrometer (MR-TOF-MS), substantiated by independent measurements from TITAN's Penning trap mass spectrometer.Atomic nuclei are highly complex quantum objects made of protons and neutrons. Despite the arduous efforts needed to disentangle specific effects from their many-body nature, the fine understanding of their structures provides key information to our knowledge of fundamental nuclear forces. One notable quantum behavior of bound nuclear matter is the formation of shell-like structures for each fermion group [1], as electrons do in atoms. Unlike for atomic shells, however, nuclear shells are known to vanish or move altogether as the number of protons or neutrons in the system changes [2]. Particular attention has been given to the emergence of strong shell effects among nuclides with 32 neutrons, pictured in a shell model framework as a full valence ν2p 3/2 orbital. Across most of the known nuclear chart, this orbital is energetically close to ν1f 5/2 , which prevents the appearance of shell signatures in energy observables. However, the excitation energies of the lowest 2 + states show a relative, but systematic, local increase below proton number Z = 24 [3]. This effect, characteristic of shell closures, has been attributed in shell model calculations to the weakening of attractive proton-neutron interactions between the ν1f 5/2 and π1f 7/2 orbitals as the latter empties, making the neutrons in the former orbital less bound [4,5]. Ab initio calculations are also extending their reach over this sector of the nuclear chart, yet no systematic investigation of the N = 32 isotones has been produced so far.

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“…These chiral NN+3N Hamiltonians were first employed to study symmetric [16] and, more recently, also asymmetric nuclear matter [31,32]. The first application to finite nuclei was in a valence-space study of sd-shell isotopes [33] and in coupled-cluster calculations of selected Ca [34,35] and Ni isotopes [36]. Of particular importance to this work is that in symmetric nuclear matter the λ NN /Λ 3N = 1.8/2.0 (EM) interaction yields an energy per particle in good agreement with the empirical value (at saturation density with a Hartree-Fock spectrum slighty too bound [32]), although at a somewhat too high density.…”

Section: Introductionmentioning

confidence: 99%

Saturation with chiral interactions and consequences for finite nuclei

Simonis¹,

Stroberg²,

Hebeler³

et al. 2017

Phys. Rev. C

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194

203

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We explore the impact of nuclear matter saturation on the properties and systematics of finite nuclei across the nuclear chart. Using the ab initio in-medium similarity renormalization group (IM-SRG), we study ground-state energies and charge radii of closed-shell nuclei from 4 He to 78 Ni, based on a set of low-resolution two-and three-nucleon interactions that predict realistic saturation properties. We first investigate in detail the convergence properties of these Hamiltonians with respect to model-space truncations for both two-and three-body interactions. We find one particular interaction that reproduces well the ground-state energies of all closed-shell nuclei studied. As expected from their saturation points relative to this interaction, the other Hamiltonians underbind nuclei, but lead to a remarkably similar systematics of ground-state energies. Extending our calculations to complete isotopic chains in the sd and pf shells with the valence-space IM-SRG, the same interaction reproduces not only experimental ground states but two-neutron-separation energies and first excited 2 + states. We also calculate radii with the valence-space IM-SRG for the first time. Since this particular interaction saturates at too high density, charge radii are still too small compared with experiment. Except for this underprediction, the radii systematics is, however, well reproduced. Our results highlight the importance of nuclear matter as a theoretical benchmark for the development of next-generation chiral interactions.

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Exploringsd-shell nuclei from two- and three-nucleon interactions with realistic saturation properties

Cited by 107 publications

References 67 publications

Effective proton-neutron interaction near the drip line from unbound states in F25,26

Effective proton-neutron interaction near the drip line from unbound states in F25,26

Dawning of the N=32 Shell Closure Seen through Precision Mass Measurements of Neutron-Rich Titanium Isotopes

Saturation with chiral interactions and consequences for finite nuclei

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