NPA39(2012)095103-ROYER-ClusterradioactivityND.pdf

Nucl. Phys. A 906 1, 2013

We systematically calculate the spontaneous fission half-lives for heavy and superheavy nuclei between U and Fl isotopes. The spontaneous fission process is studied within the semi-empirical WKB approximation. The potential barrier is obtained using a generalized liquid drop model, taking into account the nuclear proximity, the mass asymmetry, the phenomenological pairing correction, and the microscopic shell correction. Macroscopic inertial-mass function has been employed for the calculation of the fission half-life. The results reproduce rather well the experimental data. Relatively long half-lives are predicted for many unknown nuclei, sufficient to detect them if synthesized in a laboratory.

The fusion and fission barriers have been determined with a Generalized Liquid Drop Model taking into account the proximity forces acting between surfaces in regard, the charge and mass asymmetry, the shell and pairing effects and quasimolecular shapes. The heights and positions of these barriers have been compared with the empirical results deduced from the experimental data. There is an overall agreement for the fusion barrier heights for most of the reactions. These fusion barrier heights may also be calculated from a proposed analytic formula or other formulas. The empirical fission barrier heights lie always between the values given by the GLDM and neglecting the microscopic effects in the fragments and the values determined in including the deformation and shell and pairing effects of the fragments.

Nuclear Physics A, 1986

Radioactive cluster decays are studied in different nuclear regions. It is found that the decay of protons and alpha particles can be well described by the Gamow two-step mevhanism of first formation and then penetration of the particle through the Coulomb barrier. The same mechanism is found to be apt to describe the decay of heavy clusters. Formation amplitudes of proton, alphaand heavy clusters are calculated. The decay widths of all possible fragments lighter than 48Ca emitted from all possible mother nuclei with known masses are also caicutated and the most likely decaying clusters are presented. 93 235 '*

Computer Physics Communications, 1997

A numerical code to evaluate the half-lives for alpha decay, cluster radioactivity and cold fission processes for a given parent nucleus is presented. The Gamow penetrability factor is obtained by considering the pre-scission phase of two intersecting spheres in the effective one-dimensional barrier potential. Two inertia coefficients and two different modes for the shape parametrizatien are implemented in order to discuss the effect of the inertia coefficient on the half-lives of the spontaneous processes Under study.

Physical Review C, 2009

Within the preformed cluster model approach, the values of the preformation factors have been deduced from the experimental cluster decay half-lives assuming that the decay constant of the heavy-ion emission is the product of the assault frequency, the preformation factor and the penetrability. The law according to which the preformation factors follow a simple dependence on the mass of the cluster was confirmed. Then predictions for some most possible cluster decays are provided.

Journal of Physics: Conference Series, 2008

Longitudinal ternary and binary fission barriers of 36 Ar, 56 Ni and 252 Cf nuclei have been determined within a rotational liquid drop model taking into account the nuclear proximity energy. For the light nuclei the heights of the ternary fission barriers become competitive with the binary ones at high angular momenta since the maximum lies at an outer position and has a much higher moment of inertia.

Annals of Nuclear Energy, 2003

The liquid drop model predicts a linear dependence between the logarithm of spontaneous fission half-lives and the parameter Z 2 /A. This linear dependence is obtained when assuming that barrier curvature is constant. We have found this linear dependence only in long-lived even-even isotopes with Z 2 /A less than 38.5, with the same 2Z-N values. #

Physical Review C, 2012

Various types of nuclear proximity potentials are employed to study the cluster decay of radioactive nuclei, particularly those decaying to a doubly closed shell 208 Pb-daughter nucleus using the preformed cluster-decay model (PCM). The deformation effect is included up to quadrupole (β 2 ) with "optimum" cold orientations. The use of different proximity potentials modifies the potential barrier characteristics (i.e., barrier height, position, and frequency), which in turn change the preformation probability P 0 and tunneling probability P , and hence the decay half-life considerably. The analysis of 208 Pb-daughter cluster radioactivity is worked out at touching as well as at an elongated neck configuration by taking the neck-length parameter R = 0.5 fm. A wide range of barrier characteristics is covered by using various nuclear proximity potentials. We observe that Prox 1977 and Prox 1988 can reproduce the experimental half-lives very well at R = 0.5 fm; however, the use of the mod-Prox 1988 potential seems more reliable for 14 C cluster decay. The relevance of barrier characteristics of other nuclear proximity potentials is also explored in the context of 208 Pb cluster radioactivity.

Physical Review C, 2022

Background: The cluster radioactivity from the neutron-deficient trans-tin region of the nuclear landscape has given immediate attention in the nuclear structure studies. Recent prediction of the emitting clusters from the ground and intrinsic excited states of proton-rich Ba isotopes opens the direction to explore the corresponding decay characteristics. A theoretical probe is necessary for understanding the cluster decays of Ba isotopes. Purpose: In the present study, cluster-decay half-lives are calculated and their decay characteristics are investigated for even-even 112-122 Ba isotopes in both ground and intrinsic excited states along the proton drip line. Method: The preformed-cluster-decay model (PCM) is employed for estimating the decay half-lives. The preformation probability (P 0) of the cluster decay from the parent nuclei is calculated by using the well-known phenomenological formula of Blendowske and Walliser [Phys. Rev. Lett. 61, 1930 (1988)], supplemented with the newly proposed Q-value-based preformation factor for the cluster with mass A c > 28. The penetration probability is calculated from the interaction potential using the Wentzel-Kramers-Brillouin (WKB) approximation. The nucleon-nucleon (NN) potential and individual binding energy (BE) of the cluster and daughter nuclei are estimated from the microscopic relativistic mean-field formalism (RMF) and compared with those from experiments and the finite-range-droplet model for the estimation of the Q values of the cluster decays. The nonlinear RMF Lagrangian from which the effective relativistic R3Y NN potential is derived using the NL3 * parameter set is employed for the calculation of the nuclear matter densities. The R3Y and well-known M3Y potential are employed to obtain the cluster-daughter interaction potential using the double-folding procedure along with their corresponding RMF densities. The total potential along with their respective cluster decay Q values are used as input in the PCM to obtain the half-lives (T 1/2) of 112-122 Ba isotopes in their ground and intrinsic excited states. Results: The calculated half-lives (T 1/2) for relativistic R3Y NN potential and Q values are found to deviate slightly compared to the ones from the M3Y due to the difference in their barrier characteristics. We notice that at elongated neck configuration a minimum neck-length parameter R = 1.0 fm is required for R3Y potential due to its repulsive nature, whereas the value is 0.5 fm is suitable for the M3Y case. However, the estimated decay half-lives for both the potentials are in reasonably good agreement with the experimental lower limit of 114 Ba. In contrast with the ground-state decays, the inclusion of intrinsic excitation reduces the corresponding half-life values considerably but does not rule out the role of magicity. Conclusions: The sensitivity of the decay half-lives to Q values and neck-length parameter has also been demonstrated. The decay half-lives are predicted for various cluster decays from neutron-deficient Ba isotopes. Since none of the experimental half-lives for the examined clusters is precisely known yet, further studies with available observed half-lives will be needed to substantiate our findings.

Physics Reports, 1997

Introduction 1.1. Surface and Coulomb forces 1.2. Metals versus nuclear matter 1.3. Experimental and theoretical status 1.4. Main findings 1.5. Outline 2. Fission of metal droplets 2.1. Rayleigh model 2.2. Q-values 2.3. Interacting-sphere models: Polarization effects 2.4. Choice of model description 2.5. Size dependence of fission barriers 2.6. Multiply charged clusters 2.7. Influence of the model parameters on the barrier heights 2.8. Conclusions 3. Density functional calculations of fission barriers 248 248 250 251 254 255 255 255 258 259 264 265 265 266 267 268 3.1. The spherical jellium model and the extended Thomas-Fermi approximation 3.2. Calculation of the fission barrier 3.3. The two-sphere-jellium model 3.4. Chemical bond model for the outer barrier 3.5. Shell effects 4. Experimental evidence 4. I, Review of experiments 4.2. Analysis and interpretation of experiments 4.3. Summing up 5. Future perspectives 5.1. Towards fissility X = 1, the nuclear connection 5.2. Beyond fissility X = 1 6. Conclusions Appendix A. The classical image charge model Appendix B. Experimental bulk properties of monovalent metals at different temperatures References