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Delion D.S.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Delion D.S.,Academy of Romanian Scientists | Delion D.S.,Bioterra University | Dumitrescu A.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Dumitrescu A.,University of Bucharest
Atomic Data and Nuclear Data Tables | Year: 2015

We describe α-transitions to low-lying states in even-even nuclei with Z>50, N>82 using the Coherent State Model (CSM). We reproduce the energy levels and electromagnetic transition rates between the states of the ground band employing two parameters, namely the deformation parameter and the strength of the harmonic CSM Hamiltonian. The B(E2) values are described in terms of an effective charge which depends linearly on the deformation parameter. The treatment of the α-emission process is based on an α-daughter interaction containing a monopole component, calculated through a double folding procedure with a M3Y interaction plus a repulsive core simulating the Pauli principle, and a quadrupole-quadrupole (QQ) interaction. The decaying states are identified with the lowest narrow outgoing resonances obtained through the coupled channels method. The α-branching ratios to 2+ states are reproduced by means of the QQ strength. This interaction strength can be fitted with a linear dependence on the deformation parameter, as predicted by the CSM. The theoretical intensities to 4+ and 6+ states are in reasonable agreement with available experimental data. Predictions are made for spherical, transitional and well deformed even-even α-emitters. © 2014 Elsevier Inc.


Delion D.S.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Delion D.S.,Academy of Romanian Scientists | Delion D.S.,Bioterra University | Liotta R.J.,University of Stockholm | And 4 more authors.
Physical Review C - Nuclear Physics | Year: 2012

The intraband electromagnetic transitions in 210Po and 210Pb are well described within the shell model approach. In contrast, similar transitions in 212Po are one order of magnitude smaller than the experimental values, suggesting the existence of an α-cluster component in the structure of this nucleus. To probe this assumption we introduced Gaussian-like components in the single-particle orbitals. We thus obtained an enhancement of intraband transitions, as well as a proper description of the absolute α-decay width in 212Po. We analyzed the recently measured unnatural parity states I - in 212Po in terms of the collective octupole excitation in 208Pb coupled to positive parity states in 210Pb. They are connected by relatively large dipole transitions to yrast positive natural parity states. We described E1 transitions by using the same α-cluster component and an effective neutron dipole charge e ν=-eZ/A. B(E2) values and absolute α-decay width in 212Po are simultaneously described within the shell model plus a cluster component depending upon one free strength parameter. © 2012 American Physical Society.


Delion D.S.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Delion D.S.,Academy of Romanian Scientists | Delion D.S.,Bioterra University | Liotta R.J.,University of Stockholm | Wyss R.,University of Stockholm
Physical Review C - Nuclear Physics | Year: 2013

The two-proton decay process is studied by using a simple approach within the framework of scattering theory. We assume that the decaying nucleus is in a pairing state and, therefore, the two-particle wave function on the nuclear surface corresponds to the two protons moving in time-reversed states. This allows us to sustain a simplified version of the decay where the protons are simultaneously emitted with the same energies. We thus obtain a coupled system of radial equations with outgoing boundary conditions. We use similar proton-proton interactions to solve BCS equations and to describe external two-proton dynamics. A strong dependence of the pairing gap and decay width upon the proton-proton interaction strength is revealed. The experimental half-lives of 45Fe and 48Ni are reproduced by using a realistic proton-proton interaction. © 2013 American Physical Society.


Delion D.S.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Delion D.S.,Academy of Romanian Scientists | Delion D.S.,Bioterra University | Liotta R.J.,University of Stockholm
Physical Review C - Nuclear Physics | Year: 2013

It is shown that the standard shell-model representation is inadequate to explain cluster decay processes due to a deficient asymptotic behavior of the corresponding single-particle wave functions. A new representation is proposed which is derived from a mean field consisting of the standard Woods-Saxon plus spin-orbit potential of the shell model, with an additional attractive pocket potential of a Gaussian form localized on the nuclear surface. The eigenvectors of this new mean field provide a representation which retains all the benefits of the standard shell model while at the same time reproducing well the experimental absolute α-decay widths from heavy nuclei. © 2013 American Physical Society.


Dumitrescu A.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Dumitrescu A.,University of Bucharest | Delion D.S.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Delion D.S.,Academy of Romanian Scientists | Delion D.S.,Bioterra University
Physical Review C - Nuclear Physics | Year: 2016

We describe electromagnetic and favored α transitions to rotational bands in odd-mass nuclei built upon a single particle state with angular momentum projection Ω≠12 in the region 88≤Z≤98. We use the particle coupled to an even-even core approach described by the coherent state model and the coupled channels method to estimate partial α-decay widths. We reproduce the energy levels of the rotational band where favored α transitions occur for 26 nuclei and predict BE2 values for electromagnetic transitions to the band head using a deformation parameter and a Hamiltonian strength parameter for each nucleus, together with an effective collective charge depending linearly on the deformation parameter. Where experimental data are available, the contribution of the single particle effective charge to the total BE2 value is calculated. The Hamiltonian describing the α-nucleus interaction contains two terms, a spherically symmetric potential given by the double-folding of the M3Y nucleon-nucleon interaction plus a repulsive core simulating the Pauli principle and a quadrupole-quadrupole (QQ) interaction. The α-decaying state is identified as a narrow outgoing resonance in this potential. The intensity of the transition to the first excited state is reproduced by the QQ coupling strength. It depends linearly both on the nuclear deformation and the square of the reduced width for the decay to the band head, respectively. Predicted intensities for transitions to higher excited states are in a reasonable agreement with experimental data. This formalism offers a unified description of energy levels, electromagnetic and favored α transitions for known heavy odd-mass α emitters. © 2016 American Physical Society.

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