| 1. |
- Fujita, Y, et al.
(författare)
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Evidence for the existence of the [202]3/2 deformed band in mirror nuclei Mg-25 and Al-25
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 92:6
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Tidskriftsartikel (refereegranskat)abstract
- After 50 years of its prediction, the highest-lying [2 0 2]3/2 orbit among the six Nilsson single-particle orbits originating from the sd shells in prolately deformed nuclei and the rotational band on this orbit were identified. The band members were observed in Al-25 at excitation energies of 6-7.5 MeV in a high-resolution Mg-25(He-3,t) charge-exchange reaction at 0degrees having a strong selectivity for Gamow-Teller transitions. In the comparison with the analogous M1 transitions in Mg-25, the J(pi)=3/2(+) bandhead state and the excited 5/2(+) and 7/2(+) members were clearly assigned.
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| 2. |
- Fujita, Y., et al.
(författare)
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Identification of the [202]3/2 deformed band in mirror nuclei Mg-25 and Al-25 and implications for unstable nuclei
- 2006
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Ingår i: Physica Scripta. - 0031-8949. ; T125, s. 194-195
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Tidskriftsartikel (refereegranskat)abstract
- Fifty years after its prediction, the highest-lying [ 2 0 2] 3) 2 orbit among the six Nilsson single-particle orbits originating from the sd shell in prolately deformed nuclei and the rotational band on this orbit were identified. The band members were observed in Al-25 at excitation energies of 6-7.5MeV in a high-resolution Mg-25(He-3,t) charge-exchange reaction at 0 degrees having a strong selectivity for Gamow-Teller transitions. In comparison with the analogous M1 transitions in Mg-25, the J(pi) = 3/+ band-head state and the excited 5/+ and 7/2+ members were clearly assigned.
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| 3. |
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| 4. |
- Hamamoto, Ikuko, et al.
(författare)
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Deformation dependence of magnetic dipole strength below 4 MeV in doubly even rare earth nuclei
- 1991
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Ingår i: Physics Letters B. - 0370-2693. ; 260:1-2, s. 6-10
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Tidskriftsartikel (refereegranskat)abstract
- We show: (1) In the presence of the pair correlation the M1 transition strength calculated in the deformed oscillator model has a dependence on the quadrupole deformation parameter δ which is considerably stronger than linear and, in fact, it varies quadratically with δ in the limit of small deformation; (2) The deformation dependence in samarium isotopes calculated using the quasiparticle random phase approximation (QRPA) reproduces the qualitative behaviour of the recent experimental data of Ziegler, Rangacharyulu, Richter and Spieler.
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| 5. |
- Hamamoto, Ikuko
(författare)
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Deformed halo of 929F20
- 2021
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 814
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Tidskriftsartikel (refereegranskat)abstract
- Using a simple model based on the knowledge of spherical and deformed Woods-Saxon potentials, it is shown that the recent observation of halo phenomena in 29F can be interpreted as evidence for the prolate deformation of the ground state of 29F. The prolate deformation is the result of the shell structure, which is unique in one-neutron resonant levels, in particular near degeneracy of the neutron 1f7/2 and 2p3/2 resonant levels, together with the strong preference of prolate shape by the proton number Z=9. On the other hand, in oxygen isotopes spherical shape is so much favored by the proton number Z=8 that the presence of possible neutron shell-structure may not make the system deformed. Thus, the strong preference of particular shape by the proton numbers 8 and 9, respectively, together with a considerable amount of the energy difference between the neutron 1d3/2 and 2s1/2 orbits in oxygen isotopes seems to play an important role in the phenomena of oxygen neutron drip line anomaly, as was suggested by H. Sakurai et al. in 1999.
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| 6. |
- Hamamoto, Ikuko
(författare)
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Enhanced E1 transition between weakly-bound excited states in the nucleus Ne 27
- 2019
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Ingår i: Physical Review C. - 2469-9985. ; 100:1
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Tidskriftsartikel (refereegranskat)abstract
- Inspired by the recently-reported strong electric-dipole (E1) transition between the weakly-bound first and second excited states, 3/2- at 765 keV and 1/2+ at 885 keV, in the nucleus Ne171027, the E1 transition is estimated in a model by properly taking into account the effect of both deformation and weakly-bound neutrons. In addition to both the spin-parities, 1/2+ and 3/2-, and observed nearly degenerate energies of the two excited states, the observed order of magnitude of the E1 transition strength between the two states is very naturally explained in the case that these two excited states are prolately deformed, in terms of the transitions between the halo components of the wave functions of the weakly-bound odd-neutrons, s1/2→p3/2 and s1/2→p1/2, in addition to the large probability of the p3/2 component in the weakly-bound neutron [330 1/2] orbit. The large probability is the result of the shell-structure unique in weakly-bound or resonant neutrons.
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| 7. |
- Hamamoto, Ikuko, et al.
(författare)
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Form-factor of low-lying Kπ=1+ excitations in rare-earth nuclei
- 1987
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 194:1, s. 6-10
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Tidskriftsartikel (refereegranskat)abstract
- The differential cross section of inelastic electron scattering for the low-lying “collective” Kπ=1+ excitations in rare-earth nuclei is calculated in DWBA by using microscopically calculated transition-densities. In the region of low-momentum transfer (q⪅0.5 fm-1) in which experimental data are available the shape of calcualted cross sections is almost the same for all nuclei and is slightly but systematically different from the observed shape.
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| 8. |
- Hamamoto, Ikuko, et al.
(författare)
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Interplay between isoscalar and isovector correlations in neutron-rich nuclei
- 2017
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Ingår i: Physical Review C. - 2469-9985. ; 96:6
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Tidskriftsartikel (refereegranskat)abstract
- The interplay between isoscalar and isovector correlations in the 1- states in neutron-rich (N≠Z) even-even nuclei is studied, taking as examples of the nuclei, O14822 and O16824. The excitation modes explored are isovector dipole and isoscalar compression dipole modes. The self-consistent Hartree-Fock plus the random-phase approximation with the Skyrme interaction, SLy4, is solved in coordinate space so as to take properly into account the continuum effect. The isovector peak induced by isoscalar correlation, the isoscalar peak induced by isovector correlation, and the possible collective states made by both isoscalar and isovector correlations ("iS-iV pigmy resonance") are shown. The strong neutron-proton interaction in nuclei can be responsible for controlling the isospin structure of normal modes. It is explicitly shown that in the scattering by isoscalar (isovector) particles on N≠Z even-even nuclei isovector (isoscalar) strength in addition to isoscalar (isovector) strength may be populated.
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| 9. |
- Hamamoto, Ikuko
(författare)
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Shape and shell structure of lighter (N?90) neutron-rich nuclei based on a phenomenological Woods-Saxon potential
- 2019
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Ingår i: Physical Review C. - 2469-9985. ; 99:2
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Tidskriftsartikel (refereegranskat)abstract
- By using a phenomenologically successful Woods-Saxon potential, I study the shape and shell structure of (A) neutron drip line nuclei with 10≤N≤60, (B) neutron-rich nuclei related to the r process with 40≤N≤90, and (C) one-particle spectra in the potential provided by the nucleus Fe70 as a representative of so-called N=40 "island of inversion" (IoI) nuclei. First, the shell structure that is unique in very weakly bound neutrons is systematically studied, and the approximate neutron number of odd-N nuclei at which spherical (or deformed) halos can be found is pinned down. Second, the difference of the shell structure in r-process nuclei from that in stable nuclei is examined. Third, the similarity and the difference between the shell structure of N=20 IoI nuclei and that of N=40 IoI nuclei are analyzed. As a result, it is concluded that in Fe and Cr isotopes the deformation called "N=40 IoI" continuing up to N=50 is unlikely.
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| 10. |
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