| 1. |
- Doornenbal, P., et al.
(författare)
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Spectroscopy of 32Ne and the "œIsland of Inversion"
- 2009
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Ingår i: Physical Review Letters. - American Physical Society. - 0031-9007 .- 1079-7114. ; 103:3, s. 032501-1-032501-4
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first spectroscopic study of the N = 22 nucleus 32Ne at the newly completed RIKEN Radioactive Ion Beam Factory. A single γ-ray line with an energy of 722(9) keV was observed in both inelastic scattering of a 226 MeV=u 32Ne beam on a carbon target and proton removal from 33Na at 245 MeV=u. This transition is assigned to the deexcitation of the first Jπ = 2+ state in 32Ne to the 0+ ground state. Interpreted through comparison with state-of-the-art shell-model calculations, the low excitation energy demonstrates that the ‘‘island of inversion’’ extends to at least N = 22 for the Ne isotopes.
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| 2. |
- Fukuda, M., et al.
(författare)
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Reaction cross section studies at NIRS and RIBF
- 2010
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Ingår i: American Institute of Physics Conference Series. - American Institute of Physics : AIP. ; , s. 270-273
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Konferensbidrag (refereegranskat)abstract
- Reaction cross sections for stable nuclei at intermediate energies have been measured precisely and systematically. The data have been found to be reproduced nicely by the optical‐limit approximation of Glauber theory modified to include the nucleon multiple scattering effect and the Fermi‐motion effect. Applying this prescription, the nucleon density distribution of 17Ne has been studied. The surface structure of 8B and 11Be has been also studied using this prescription and hydrogen targets. Using the RIBF that has just started application to studies of exotic nuclei, neutron‐rich Ne isotopes around the Island of Inversion have been investigated through measurements of their interaction cross sections.
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| 3. |
- Kuboki, T.a, et al.
(författare)
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Measurement of interaction cross-sections for neutron-rich Na isotopes
- 2011
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Ingår i: Acta Physica Polonica B. - : Jagellonian University. - 0587-4254 .- 1509-5770. ; 42:3-4, s. 765-768
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Tidskriftsartikel (refereegranskat)abstract
- The interaction cross-sections (σI) of neutron-rich Na isotopes, 23-35Na, on C target have been measured at 250A MeV using the RI beam factory (RIBF) at RIKEN. Mass dependence of σI for 27-35Na suggests monotonic growth of the skin thickness. The root-mean-square nuclear matter radii (rm) of 23-35Na were deduced from observed σI via a Glauber-type calculation. These rm are in a good agreement with the theoretical prediction by relativistic mean field model (RMF). rm of 33-35Na were determined for the first time.
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| 4. |
- Ozawa, A., et al.
(författare)
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Charge-changing cross sections of 30Ne, 32,33Na with a proton target
- 2014
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89, s. 044602-1-044602-5
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Tidskriftsartikel (refereegranskat)abstract
- The total charge-changing, charge pick-up, and partial charge-changing cross sections of very neutron-rich nuclei (30Ne, 32,33Na) with a proton target have been measured at ~240A MeV for the first time. We introduced the phenomenological correction factor in Glauber-model calculations for the total charge-changing cross sections with the proton target, and applied it to deduce the proton radii of these nuclei. For 30Ne and 32Na, the neutron skin thicknesses of the nuclei were deduced by comparing the proton radii with the matter radii deduced from the interaction cross-section measurements. A significant thick neutron-skin has been observed for the nuclei. We also found that the charge pick-up cross sections are much larger than those in the systematics of stable nuclei.
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| 5. |
- Takechi, M., et al.
(författare)
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Interaction cross sections for Ne isotopes towards the island of inversion and halo structures of 29Ne and 31Ne
- 2012
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Ingår i: Physics Letters B. - Elsevier : Elsevier BV. - 0370-2693 .- 1873-2445. ; 707:3-€“4, s. 357-361
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Tidskriftsartikel (refereegranskat)abstract
- Interaction cross sections (σI) for Ne isotopes from the stability line to the vicinity of the neutron dripline have been measured at around 240 MeV/nucleon using BigRIPS at RIBF, RIKEN. The σI for 27–32Ne in every case exceed the systematic mass-number dependence of σI for stable nuclei, which can be explained by considering the nuclear deformation. In particular the σI for 29Ne and 31Ne are significantly greater than those of their neighboring nuclides. These enhancements of σI for 29Ne and 31Ne cannot be explained by a single-particle model calculation under the assumption that the valence neutron of 29Ne (31Ne) occupies the 0d3/2 (0f7/2 ) orbital, as expected from the standard spherical shell ordering. The present data suggest an s dominant halo structure of 29Ne and s- or p-orbital halo in 31Ne.
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| 6. |
- Takechi, M., et al.
(författare)
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Measurements of nuclear radii for neutron-rich Ne isotopes 28-32Ne
- 2010
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Ingår i: Nuclear Physics A. - Elsevier : Elsevier BV. - 0375-9474 .- 1873-1554. ; 834:1-4, s. 412c-415c
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Tidskriftsartikel (refereegranskat)abstract
- Interaction cross sections (σI) for neutron-rich Ne isotopes, 28-32Ne on C target have been measured at 240A MeV using the RIBF at RIKEN. A large enhancement of σI beyond the systematics of stable nuclei have been observed for neutron-rich Ne isotopes, particularly for 31Ne. The possible halo structure for 29,31Ne which would be caused by the lowering of the pf-shell and nuclear deformation of Ne isotopes are discussed by the preliminary analysis.
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| 7. |
- Hirano, T., et al.
(författare)
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An Earth-sized Planet around an M5 Dwarf Star at 22 pc
- 2023
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 165:3
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Tidskriftsartikel (refereegranskat)abstract
- We report on the discovery of an Earth-sized transiting planet (R p = 1.015 ± 0.051 R ⊕) in a P = 4.02 day orbit around K2-415 (EPIC 211414619), an M5V star at 22 pc. The planet candidate was first identified by analyzing the light-curve data obtained by the K2 mission, and it is here shown to exist in the most recent data from TESS. Combining the light curves with the data secured by our follow-up observations, including high-resolution imaging and near-infrared spectroscopy with IRD, we rule out false-positive scenarios, finding a low false-positive probability of 2 × 10−4. Based on IRD’s radial velocities of K2-415, which were sparsely taken over three years, we obtain a planet mass of 3.0 ± 2.7 M ⊕ (M p < 7.5 M ⊕ at 95% confidence) for K2-415b. Being one of the lowest-mass stars (≈0.16 M ⊙) known to host an Earth-sized transiting planet, K2-415 will be an interesting target for further follow-up observations, including additional radial velocity monitoring and transit spectroscopy.
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| 8. |
- Shimoura, S., et al.
(författare)
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Lifetime of the isomeric O-2(+) state in Be-12
- 2007
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 654:3-4, s. 87-91
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Tidskriftsartikel (refereegranskat)abstract
- Mean lifetime tau of the isomeric O-2(+) state in Be-12 has been determined by measuring decay spectra of delayed y-rays from stopped Be-12 2 nuclei produced by the projectile fragmentation of O-18 at 100 A MeV. A consistent value of tau = 331 +/- 12 ns was obtained from the time spectra of the E2 gamma decay to the 2(1)(+) state and the positron annihilation following the E0 decay to the ground state. Based on the observed branching ratio between the E2 and E0 decays, transition strengths of the two decay modes were deduced to be B(E2; O-2(+) -> 2(1)(+)) = 7.0 +/- 0.6 e(2) fm(4) and 2 1 1 (O-2(+) Sigma(i) e(i) r(i)(2) O-1(+)), = 0.87 +/- 0.03 e fM(2), respectively. (C) 2007 Elsevier B.V. All rights reserved.
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| 9. |
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| 10. |
- Ideguchi, E., et al.
(författare)
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Position sensitivity of a segmented planar Ge detector
- 2003
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 496:03-feb, s. 373-384
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Tidskriftsartikel (refereegranskat)abstract
- A method to extract depth of interaction information for gamma-rays in a segmented planar Ge detector is presented. The method is demonstrated on signals from a segmented detector which were stored by a digital oscilloscope event by event and analysed off-line. Event samples were acquired for different interaction points in the detector. A Compton scatter coincidence detection technique ensured that the event samples were highly enriched in single-interaction events. By analysing pulse shapes and the relative timing between anode pulses and the pulses from the irradiated cathode segment, a position sensitivity of 1-2 mm in the depth direction was deduced. A similar transverse position sensitivity was inferred by studying image charge pulses on neighbouring segments.
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