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- Zanon, I., et al.
(författare)
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High-Precision Spectroscopy of 20O Benchmarking Ab Initio Calculations in Light Nuclei
- 2023
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 131:26
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Tidskriftsartikel (refereegranskat)abstract
- The excited states of unstable 20O were investigated via γ-ray spectroscopy following the 19O(d,p)20O reaction at 8 AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2+2 and 3+1 states were firmly established. From the γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2+2 and 3+1 states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.
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- Tanabe, T., et al.
(författare)
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Resonant neutral particle emission in collisions of electrons with protonated peptides with disulfide bonds at high energies
- 2011
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 504:1-3, s. 83-87
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Tidskriftsartikel (refereegranskat)abstract
- Electron-ion collisions were studied for various protonated peptide monocations with disulfide bonds, using an electrostatic storage-ring equipped with a merged-electron-beam device. Resonant neutral particle emissions at the energies of 6-7 eV were observed, as well as a rise towards zero-energy, which are typical electron-capture dissociation profiles. The presence of disulfide (S-S) bonds tends to enhance the resonant bump heights. Chemical nature of the amino-acid residues adjacent to cysteines appears to correlate with the bump strength. Molecular-dynamical simulations help clarify the role of molecular vibration modes in the electron-capture dissociation process. (C) 2011 Elsevier B. V. All rights reserved.
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- Vernon, A. R., et al.
(författare)
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Nuclear moments of indium isotopes reveal abrupt change at magic number 82
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 607:7918, s. 260-265
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Tidskriftsartikel (refereegranskat)abstract
- In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular ‘magic’ numbers of nucleons, nuclear properties are governed by a single unpaired nucleon1,2. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics3–5. The indium isotopes are considered a textbook example of this phenomenon6, in which the constancy of their electromagnetic properties indicated that a single unpaired proton hole can provide the identity of a complex many-nucleon system6,7. Here we present precision laser spectroscopy measurements performed to investigate the validity of this simple single-particle picture. Observation of an abrupt change in the dipole moment at N = 82 indicates that, whereas the single-particle picture indeed dominates at neutron magic number N = 82 (refs. 2,8), it does not for previously studied isotopes. To investigate the microscopic origin of these observations, our work provides a combined effort with developments in two complementary nuclear many-body methods: ab initio valence-space in-medium similarity renormalization group and density functional theory (DFT). We find that the inclusion of time-symmetry-breaking mean fields is essential for a correct description of nuclear magnetic properties, which were previously poorly constrained. These experimental and theoretical findings are key to understanding how seemingly simple single-particle phenomena naturally emerge from complex interactions among protons and neutrons. © 2022, The Author(s), under exclusive licence to Springer Nature Limited.
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