| 1. |
- Betan, Rodolfo Id., et al.
(författare)
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Description of the continuum part of the spectrum by using the complex. energy plane
- 2005
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 31:8, s. S1329-S1336
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Tidskriftsartikel (refereegranskat)abstract
- Processes occurring in the continuum part of the spectrum are described by using a basis consisting of bound and antibound states plus Gamow resonances and the continuum background. The calculations, performed in the complex energy plane, are applied to the study of weakly bound nuclei. The influence of antibound states upon physical quantities in halo nuclei is assessed.
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| 2. |
- Civitarese, O., et al.
(författare)
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Effects of resonant and continuum states on the neutrino-nucleus cross section
- 2008
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 78:6, s. 064308-
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Tidskriftsartikel (refereegranskat)abstract
- Estimates of the neutrino-nucleus cross section, for the charged-current process nu + Pb-208 -> e(-) + Bi-208*, are presented. The nuclear structure calculations were performed by considering bound, resonant, and continuum states in the single-particle basis used to construct correlated proton-particle neutron-hole configurations. The observed features of the spectrum of Bi-208 were reproduced, as accurately as possible, by diagonalizing a phenomenological multipole-multipole interaction. Calculations of the cross section, for values of q <= 200 MeV, were performed, and the dependence of the results on the choice of the residual proton-neutron interaction was investigated. It is found that the inclusion of resonant states in the calculation of the nuclear wave functions increases the neutrino-nucleus cross section and that the contribution of the continuum is negligible.
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| 3. |
- Delion, D. S., et al.
(författare)
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alpha decay of high-spin isomers in superheavy nuclei
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 044301-
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Tidskriftsartikel (refereegranskat)abstract
- Hindrance factors corresponding to alpha decay from two quasiparticle isomeric high K states are evaluated in superheavy nuclei. We found that the hindrance factors are very sensitive to the deformations and, therefore, they may constitute a powerful tool to extract spectroscopic information in these nuclei. The hindrance factors turn out to be very large, specially for nonaligned configurations. This indicates that if one of such states is reached the parent nucleus may become isomeric. It is also possible that alpha decay may not proceed through ground state to ground state chains but rather through excited states.
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| 4. |
- Delion, D. S., et al.
(författare)
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Probing nuclear mean field by proton emission
- 2007
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Ingår i: Romanian Reports in Physics. - 1221-1451 .- 1841-8759. ; 59:2, s. 411-417
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Tidskriftsartikel (refereegranskat)abstract
- We show that proton emission is a valuable tool to investigate mean field properties of exotic proton rich nuclei. We give a formula that relates the logarithm of the half-life, corrected by the centrifugal barrier, with the Somerfeld parameter in proton decay processes. The corresponding experimental data lie on two straigth lines which appear as a result of a sudden change in the nuclear shape, marking two regions of deformation. This feature provides a powerfull tool to assign experimentally quantum numbers and deformations in proton emitters.
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| 5. |
- Delion, D. S., et al.
(författare)
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Systematics of proton emission
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 96:7, s. 072501-
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Tidskriftsartikel (refereegranskat)abstract
- A very simple formula is presented that relates the logarithm of the half-life, corrected by the centrifugal barrier, with the Coulomb parameter in proton decay processes. The corresponding experimental data lie on two straight lines which appear as a result of a sudden change in the nuclear shape marking two regions of deformation independently of the angular momentum of the outgoing proton. This feature provides a powerful tool to assign experimentally quantum numbers in proton emitters.
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| 6. |
- Delion, D. S., et al.
(författare)
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Theories of proton emission
- 2006
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Ingår i: Physics reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 424:3, s. 113-174
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Forskningsöversikt (refereegranskat)abstract
- Proton emission studies are presently the focal point of nuclear structure as well as nuclear reaction investigations in rare nuclei. Theoretical approaches to investigate the properties of such nuclei by using proton emission are reviewed. We analyse time-dependent and stationary formalisms within adiabatic and non-adiabatic methods. We investigate and compare the use of resonant Gamow states within coupled channels, R-matrix and distorded wave approaches. We give a description of odd-even as well as odd-odd proton emitters using axially symmetric or triaxial potentials. The emission to excited states of the daughter nucleus and angular distribution of the emitted proton is discussed. The status of numerical applications for both spherical and deformed approaches is reviewed. The importance of proton emission in analysing the properties of nuclear matter under exotic conditions is emphasized. in the appendices we give all technical details necessary to compute the observables connected with proton emission.
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| 7. |
- Dussel, G. G., et al.
(författare)
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Collective excitations in the continuum
- 2009
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 80:6, s. 064311-
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Tidskriftsartikel (refereegranskat)abstract
- Pairing (particle-particle) giant resonances are analyzed within a shell-model formalism in the complex energy plane with the aim of understanding why they have not been observed so far. A comparison is made with the equivalent particle-hole mode by applying the formalism to the analysis of the well-understood particle-hole giant resonance. It is found that because of the proper treatment of the continuum intrinsic to the formalism, giant pairing resonances lie much higher than previously predicted and that some of them may be too wide to be observed, whereas others are meaningful excitations. For these, new experimental searches are proposed.
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| 8. |
- Dussel, G. G., et al.
(författare)
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One- and two-quasiparticle states in the complex energy plane
- 2007
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 789, s. 182-200
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Tidskriftsartikel (refereegranskat)abstract
- One- and two-quasi particle states are studied in the complex energy plane. It is found that the pairing interaction does not change the character of the complex state. If a normal state is a physically meaningful resonance, then it will remain as such throughout the shell and if it is unphysical it will also remain as such throughout the shell. An important consequence of this is that it justifies the use of bound representations to evaluate many-body systems within the shell-model in cases where the single-particle states are narrow resonances. The character of two-quasiparticle states may oscillate between meaningful resonances and unphysical complex excitations as the number of particles increases.
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| 9. |
- Hadinia, Baharak, et al.
(författare)
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In-beam gamma-ray and alpha-decay spectroscopy of 170Ir
- 2007
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 044312-1-044312-8
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the highly neutron deficient odd-odd nucleus Ir-170 have been investigated. The experiment was performed using the Sn-112(Ni-60, pn)Ir-170 reaction and employing the recoil-decay tagging technique. Gamma rays were detected using the JUROGAM gamma-ray spectrometer and those belonging to Ir-170 were selected based on recoil identification provided by the RITU gas-filled recoil separator and the GREAT spectrometer at the RITU focal plane. A partial level scheme of Ir-170 is presented for the first time. New alpha-decay branches are assigned to Ir-170 and a tentative level structure for Re-166 is deduced from a study of the alpha-decay fine structure and the associated alpha-gamma correlations.
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| 10. |
- Id Betan, Rodolfo M, et al.
(författare)
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Complex shell model representation including antibound states
- 2005
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 72:5, s. 054322-
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Tidskriftsartikel (refereegranskat)abstract
- A generalization of the complex shell model formalism is presented that includes antibound states in the basis. These states, together with bound states, Gamow states, and the continuum background, represented by properly chosen scattering waves, form a representation in which all states are treated on the same footing. Two-particle states are evaluated within this formalism, and observable two-particle resonances are defined. The formalism is illustrated in the well-known case of Li-11 in its bound ground state and in Ca-70(g.s.), which is also bound. Both cases are found to have a halo structure. These halo structures are described within the generalized complex shell model. We investigated the formation of two-particle resonances in these nuclei, but no evidence of such resonances was found.
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