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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 | Suhonen J.,University of Jyväskylä
Physical Review C | Year: 2017

We apply the proton-neutron deformed quasiparticle random-phase approximation (pn-dQRPA) to describe the low-lying (E≤6 MeV) 1+ Gamow-Teller (GT) strength functions in odd-odd deformed nuclei which participate as intermediate nuclei in two-neutrino double-β-decay (2νββ) transitions within the mass range A=70-176. In deriving equations of motion we use a single-particle basis with projected angular momentum, provided by the diagonalization of a spherical mean field furnished with a quadrupole-quadrupole interaction. The schematic residual Hamiltonian contains pairing and proton-neutron interaction terms in particle-hole (ph) and particle-particle (pp) channels, with constant strengths. By adopting constant particle-hole and particle-particle strengths we are able to describe the positions of the giant GT resonance and the measured half-lives of the 2νββ decays over the whole mass range A=70-176. At the same time we obtain a good agreement with the measured low-lying GT β- strength functions. By using the adopted ph and pp strengths, we predict the half-lives of a number of deformed 2νββ emitters and the low-lying GT strength functions of the corresponding odd-odd intermediate nuclei for their possible experimental tests in the future. © 2017 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.,KTH Royal Institute of Technology | And 2 more authors.
Physical Review C - Nuclear Physics | Year: 2014

We analyze the α-decay fine structure to excited 02+ states in Hg and Rn isotopes. These states are described as minima in the potential energy surface (PES) provided by the standard deformed Woods-Saxon plus pairing approach. We also investigate α decay from the excited state P(02+) in the parent nucleus by evaluating the corresponding hindrance factor (HF). By analyzing the experimental HF's we find the remarkable property that the ground and excited states D(01+) and D(02+) in the daughter nuclei are occupied with almost equal probabilities if there is no excited P(0+) states in the parent nucleus. Moreover, if there exists an excited state P(02+) then the occupation probability of this state is 25%. © 2014 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.,KTH Royal Institute of Technology | Wyss R.,KTH Royal Institute of Technology
Physical Review C - Nuclear Physics | Year: 2015

We compare the quantum mechanical procedures to estimate the total α-decay width from deformed nuclei in the laboratory and intrinsic systems of coordinates. Our analysis shows that the total half-life estimated in the intrinsic frame by neglecting the rotational motion of the core (adiabatic approach) is one order of magnitude smaller at β2=0.3 than the corresponding value in the spherical case. A similar calculation in the laboratory system of coordinates by considering the core motion (giving the correct theoretical estimate) predicts a reduction by only a factor of 2. The widely used "angular WKB" (Wentzel-Kramers-Brillouin) semiclassical procedure provides decay widths which are comparable to the adiabatic approach. We propose a new and very simple semiclassical "angular momentum WKB" procedure to evaluate the decay width in deformed nuclei. It provides decay widths very close to the ones obtained by the exact laboratory coupling channels procedure. ©2015 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 | 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.


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.


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
Physical Review C - Nuclear Physics | Year: 2015

We systematize the available experimental material concerning α-decay transitions to low-lying excited states in even-even and odd-mass emitters. We generalize our previous theoretical prediction concerning the linear dependence between hindrance factors and the excitation energy for transitions in even-even α emitters. Thus, we show that α intensities for transitions to excited states depend linearly upon the excitation energy for all known even-even and odd-mass α emitters. It turns out that the well-known Viola-Seaborg law for α-decay transitions between ground states can be generalized for transitions to excited states. This rule can be used to predict any α-decay half-life to a low-lying excited state. © 2015 American Physical Society. ©2015 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.


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.


Mirea M.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Sandulescu A.,Bioterra University | Sandulescu A.,Institute for Advanced Studies in Physics | Delion D.S.,Horia Hulubei National Institute of Physics and Nuclear Engineering | Delion D.S.,Bioterra University
Nuclear Physics A | Year: 2011

The decay dynamical path is determined within the macroscopic-microscopic model for the emission of 24Ne from 232U. The nuclear shape parametrization is characterized five degrees of freedom. The single particle energies and the nucleon wave functions are obtained within the superasymmetric Woods-Saxon two center shell model. It turns out that the cluster decay follows a potential magic valley, starting from the ground state of the parent and reaching a configuration of two touching nuclei at scission. A small pocket in the potential barrier is evidenced, as a result of large shell effects in the nascent fragments. The half-life is computed by using several approaches for the effective mass. It is shown that the inertia within by the Gaussian overlap approach gives the closest values to the experimental ones. Half-lives for different cluster decays are predicted. The theoretical values are compared to various phenomenological estimates. © 2011 Elsevier B.V.


Iancu M.,Bioterra University
European Journal of Science and Theology | Year: 2014

Bioethical education, as a component and as a cornerstone of moral education, looks at the education of young people, high school and college students so as they will be able to apply both moral laws and Biology laws in their subsequent scientific research and endeavours. Bioethical education is absolutely necessary in school education, especially in the final years of high school. However, it is of the utmost importance in higher education in the profile of Biology, encompassing heuristic strategies, interactive teaching methods, active traditional teaching methods and new, modern methods resorting to multi-media and electronic platforms.

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