| 1. |
- 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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| 2. |
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| 3. |
- Hamamoto-Kuroda, Ikuko, et al.
(författare)
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Self-consistent Hartree-Fock and RPA Green's function method indicate no pygmy resonance in the monopole response of neutron-rich Ni isotopes
- 2014
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 90:3
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Tidskriftsartikel (refereegranskat)abstract
- The random phase approximation (RPA) monopole strength and the unperturbed particle-hole excitation strength are studied, in which the strength in the continuum is properly treated without discretizing unbound particle spectra. The model is the self-consistent Hartree-Fock calculation and the RPA Green's function method with Skyrme interactions. Numerical examples are the Ni isotopes, especially Ni-68(28)40, in which an experimental observation of a low-lying peak with an appreciable amount of monopole strength at 12.9 +/- 1.0 MeV was recently reported. In the present study it is concluded that sharp monopole peaks with the width of the order of 1 MeV can hardly be expected for Ni-68 in that energy region. Instead, a broad shoulder of monopole strength consisting of neutron excitations to nonresonant one-particle states (called "threshold strength") with relatively low angular momenta (l, j) is obtained in the continuum energy region above the particle threshold, which is considerably lower than that of the isoscalar giant monopole resonance. In the case of monopole excitations of Ni-68 there are no unperturbed particle-hole states below 20 MeV, in which the particle expresses a neutron (or proton) resonant state. It is emphasized that in the theoretical estimate a proper treatment of the continuum is extremely important.
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| 4. |
- Hamamoto-Kuroda, Ikuko, et al.
(författare)
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Weakly-bound p3/2 neutrons and spin-response function in the many-body pair-correlation of neutron drip line nuclei
- 2004
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:3
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Tidskriftsartikel (refereegranskat)abstract
- Solving the simplified model of the Hartree-Fock Bogoliubov equation in coordinate space with the correct asymptotic boundary conditions, the spin-orbit splitting, occupation probabilities, effective pair-gap, mean square radius, and spin-response function are studied for weakly bound p neutrons. As the binding energy of p3∕2 neutrons becomes small or approaches zero, the spin-orbit splitting p3∕2−p1∕2 in the one-body potential drastically decreases and, at the same time, the effective pair-gap for the p neutrons becomes small, while the occupation probability of the p3∕2 level decreases only slightly. Consequently, in that limit low-lying broader spin response with almost constant amount of total strength appears with the peak moving toward very low excitation energies.
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| 5. |
- Moeller, Peter, et al.
(författare)
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Global Calculation of Nuclear Shape Isomers
- 2009
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Ingår i: Physical Review Letters. - 1079-7114. ; 103:21
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Tidskriftsartikel (refereegranskat)abstract
- To determine which nuclei may exhibit shape isomerism, we use a well-benchmarked macroscopic-microscopic model to calculate potential-energy surfaces as functions of spheroidal (epsilon(2)), hexadecapole (epsilon(4)), and axial-asymmetry (gamma) shape coordinates for 7206 nuclei from A=31 to A=290. We analyze these and identify the deformations and energies of all minima deeper than 0.2 MeV. These minima may correspond to characteristic experimentally observable shape-isomeric states. Shape isomers mainly occur in the A=80 region, the A=100 region, and in an extended region centered around Pb-208. We compare our model to experimental results for Kr isotopes. Moreover, in a plot versus N and Z we show for each of the 7206 nuclei the calculated number of minima. The results reveal one fairly unexplored region of shape isomerism, which is experimentally accessible, namely the region northeast of Pb-208(82).
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| 6. |
- Parizot, Etienne, et al.
(författare)
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The JEM-EUSO Program for UHECR Studies from Space
- 2023
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Ingår i: Proceedings 6th international symposium on Ultra High Energy Cosmic Rays (UHECR). - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- To take up the challenge of understanding the origin of the ultra-high-energy cosmic rays (UHECRs), new observational means appear necessary. The JEM-EUSO Collaboration has undertaken to open the space road to UHECR studies. For more than a decade, it has been developing a realistic program to measure the UHECRs from space with unprecedented aperture, together with complementary scientific objectives in a broader multidisciplinary context. Several intermediate missions have already been completed (on the ground: EUSO-TA; under stratospheric ballons: EUSO-Balloon and EUSO-SPB1; in space: TUS, and on-board the ISS: MINI-EUSO), and others are in preparation for flight (EUSO-SPB2), under review (K-EUSO: currently on hold), or proposed for the next decade (POEMMA). We report on the general status of the JEM-EUSO program, underlining that its technology has now reached operational maturity, and is ready for actual cosmic-ray shower detection from above.
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