Effect of nuclear deformation on α-decay half-lives (original) (raw)
Related papers
Penetration factor in deformed potentials: Application to α decay with deformed nuclei
A new averaging process of the calculation of α-decay half-lives for heavy and superheavy nuclei is studied in the framework of a deformed density-dependent cluster model. The potential between a spherical α particle and a deformed daughter nucleus is calculated numerically from the double-folding model by the multipole expansion method. The nuclear potential is calculated at each α-particle emission angle applying the Bohr-Sommerfeld condition at each case. The penetration factors and the half-lives for all the emission angles are evaluated with the new averaging process and compared with older values based on a fixed value of the nuclear potential depth. Finally, the half-lives of 83 even-even heavy nuclei in the atomic-number range 82-118 are calculated by the two methods and compared with their experimental values and the corresponding half-lives of the spherical daughter nuclei.
Α-Decay Spectroscopy of Deformed Nuclei Reexamined
Physical Review C, 2008
We perform an extensive analysis of α-decays to 2 + and 4 + states in deformed even-even nuclei by using the stationary coupled channels approach. Collective excitations are described within the rigid rotor model. The α-nucleus interaction is given by a double folding procedure with M3Y plus Coulomb nucleon-nucleon forces. We use a repulsive potential with one independent parameter in order to localize the α-particle on the nuclear surface and to fit the experimental Q-value. The decaying state is identified with the first resonance inside the resulting pocket-like potential, as suggested by microscopic calculations. We obtain a good agreement with existing experimental data concerning decay widths to J = 2 + , 4 + states. The total α-decay half-lives agrees very well with experimental values by fitting the spectroscopic factor in terms of charge and neutron numbers separately for Z < 82 and Z > 82. We give predictions for intensities and hindrance factors for 52 even-even α-emitters with β 2 > 0.15 and E 2 + < 200 kev. Comparison between the phenomenological and microscopic spectroscopic factors revealed large α-clustering components for nuclei close and above N = 82, Z = 82, N = 126 magic numbers.
Alpha decay from deformed nuclei
Nuclear Physics A, 1987
The reaction-theoretical formulation of (Y decay theory is extended to deformed nuclei in a particle-plus-rotor model and adapted for the use of harmonic oscillator functions. For testing purposes the formalism is applied to the decay of nuclides with reasonably well-established ground state shapes (spherical as well as deformed).
Influence of nuclear deformation on the 2νββ decay
Physics Letters B, 1993
The effect of the nuclear deformation on the 2uflfl decay is investigated within a schematic model. Using a projected single particle basis having the energies close to those of Nilsson levels one treats a model Hamiltonian consisting of pairing, spin-isospin and quadrupole-quadrupole interactions. The successive approaches are the BCS, QRPA and the first order boson expansion. The Gamow-Teller transition matrix element is evaluated as a function of the nuclear deformation and the strength of the 1 + particle-particle (pp) interaction.The dependence of the properties of the
arXiv: Nuclear Theory, 2018
In this work study on alpha decay chains emerging from isotopes of Z = 122 superheavy nuclei is carried out with emphasize on nuclear deformations and Langer modification. The interest in this particular superheavy nuclei is due to the recent experimental efforts to synthesize the isotope ^{299}120 in a fusion reaction at the velocity filter SHIP (GSI Darmstadt), which makes synthesis of Z = 122 nuclei to occur in the near future, and in turn will give the experimentalist the chance observe the decays associated with the isotopes of this nuclei. We perform our calculations by choosing the Woods Saxon potential for nuclear interaction, along with Coulomb potential and centrifugal potential within the framework of the WKB method. When the centrifugal term is taken in the total potential and WKB integral is done over 1D radial coordinate, it requires the use of Langer modification wherein (l + 1/2 )^2 replaces l(l +1) for consistency of WKB wave function. Hence we have used this Langer...
Alpha decay half-lives of superheavy nuclei in the WKB approximation
Nucleus, 2011
Alpha decay half-lives of superheavy nuclei are obtained in the context of barrier penetration theory built with the use of Coulomb and proximity potentials, taking into account the quadrupole deformations of nuclei. It is estimated from a classical viewpoint, a possible maximum value of the angular momentum of alpha particles emitted from odd and odd-odd nuclei. Masses and deformations of nuclei are obtained from the macro-microscopic method, with the use of the twocenter shell model. Alpha-decay half-lives are compared with recent experimental results. Se obtienen períodos de semidesintegración alfa en el marco de la teoría de penetración de barrera, esta última construida con el uso de los potenciales de proximidad y de Coulomb, teniendo en cuenta la deformación cuadrupolar de los núcleos. Se estima, desde el punto de vista clásico, el máximo valor posible del momento angular de las partículas alfa emitidas por núcleos impares e impar-impar. Las masas y las deformaciones de los núcleos se obtienen según el método macromicroscópico, con el uso del modelo de capas de dos centros. Los períodos de semidesintegración alfa se comparan con resultados experimentales.
Double-beta decay in deformed nuclei
2002
The pseudo SU(3) approach has been used to describe many low-lying rotational bands, as well as BE(2) and B(M1) intensities in rare earth and actinide nuclei, both with even-even and odd-mass numbers [1, 2, 3, 4, 5, 6]. The ββ half lives of some of these parent nuclei to the ground and excited states of the daughter ones were evaluated for the two and zero neutrino emitting modes [7, 8, 9, 10, 11] using the pseudo SU(3) scheme. The predictions were in good agreement with the available experimental data for 150 Nd and 238 U. The double electron capture half-lives of 156 Dy, 162 Er and 168 Yb were also studied using the same formalism [12]. The first nuclei was found to be the best candidate for experimental detection, with a half-life of ≈ 10 24 yr to the first excited 0 + state in 156 Gd. There are strong selection rules which restrict the two neutrino mode of the ββ decay in some other nuclei, including 160 Gd. Experimental limits for the ββ decay of 160 Gd have been reported [13, 14]. Recently it was argued that the strong cancellation of the 2ν mode in the ββ decay of 160 Gd would suppress the background for the detection of the 0ν mode [15]. In the present contribution we extend the previous research [7, 8, 9, 10, 11] evaluating the ββ half lives of 160 Gd using the pseudo SU(3) model. While the 2ν mode is forbidden when the most probable occupations are considered, states with different occupation numbers can be mixed through the pairing interaction. The amount of this mixing is evaluated using perturbation theory. The possibility of observing the ββ decay in 160 Gd is discussed for both the 2ν and 0ν modes.
Shell model calculations for heavy deformed nuclei
1998
The pseudo SU(3) model is shown to be a powerful scheme for describing the excitation spectra as well as B(E2) and B(MI) transition strengths in heavy deformed nuclei. It is also useful for describing double beta decay amplitudes for transitions from the ground state of an even-even nucleus to the ground and excited states of the daughter nucleus, both for the two and zero neutrino emitting modes. The existence of selection rules which strongly restricts the decays is discussed. Anti-correlations between the quadrupole deformation and the Gamow-Teller (GT +) strength axe found in an extension of the pseudo SU(3) model which explicitly includes pa~ring, which is also able to describe the fragmentation of the scissors mode. The projected shell model is introduced and proposed as an alternate means for studying single and double beta decay processes.
Α-Decay Half-Lives of Superdeformed Superheavy Nuclei
2013
We calculate the binding energy, root-mean-square radius, and quadrupole deformation parameter for the recent, possibly discovered superheavy element Z = 122, using the axially deformed relativistic mean-field (RMF) and nonrelativistic Skyrme Hartree-Fock (SHF) formalisms. The calculation is extended to include various isotopes of Z = 122 element, starting from A = 282 to A = 320. We predict highly deformed structures in the ground state for all the isotopes. A shape transition appears at about A = 290 from a highly oblate to a large prolate shape, which may be considered as the superdeformed and hyperdeformed structures of the Z = 122 nucleus in the mean-field approaches. The most stable isotope (largest binding energy per nucleon) is found to be 302 122, instead of the experimentally observed 292 122.
Predictions on the alpha decay half lives of superheavy nuclei with Z= 113 in the range 255 ≤A≤ 314
Nuclear Physics A, 2016
An intense study of the alpha decay properties of the isotopes of superheavy element Z=113 have been performed within the Coulomb and proximity potential model for deformed nuclei (CPPMDN) within the wide range 255 ≤ A ≤ 314. The predicted alpha decay half lives of 278 113 and 282 113 and the alpha half lives of their decay products are in good agreement with the experimental data. 6α chains and 4α chains predicted respectively for 278 113 and 282 113 are in agreement with the experimental observation. Our study shows that the isotopes in the mass range 278 ≤ A ≤ 286 will survive fission and can be synthesized and detected in the laboratory via alpha decay. In our study, we have predicted 6α chains from 279 113, 4α chains from 286 113, 3α chains from 280,281,283 113, 2α chains from 284 113 and 1α chain from 285 113. We hope that these predictions will be a guideline for future experimental investigations.