Cluster radioactivity with effects of deformations and orientations of nuclei included (original) (raw)
Related papers
Preformation of clusters in heavy nuclei and cluster radioactivity
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.
Cluster radioactivity and clustering formation in nuclei
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 '*
Pb208-daughter cluster radioactivity and the deformations and orientations of nuclei
Physical Review C, 2009
The role of deformations and orientations of nuclei is studied for the first time in cluster decays of various radioactive nuclei, particularly those decaying to doubly closed shell, spherical 208 Pb daughter nucleus. Also, the significance of using the correct Q-value of the decay process is pointed out. The model used is the preformed cluster model (In this model, cluster emission is treated as a tunneling of the confining interaction barrier by a cluster considered already preformed with a relative probability P 0 . Since both the scattering potential and potential energy surface due to the fragmentation process in the ground state of the parent nucleus change significantly with the inclusion of deformation and orientation effects, both the penetrability P and preformation probability P 0 of clusters change accordingly. The calculated decay half-lives for all the cluster decays investigated here are generally in good agreement with measured values for the calculation performed with quadrupole deformations β 2 alone and "optimum" orientations of cold elongated configurations. In some cases, particularly for 14 C decay of Ra nuclei, the inclusion of multipole deformations up to hexadecapole β 4 is found to be essential for a comparison with data. However, the available β 4 -values, particularly for nuclei in the mass region 16 A 26, need be used with caution.
Physical Review C, 2003
The stability and/or instability of the deformed and superdeformed nuclei, 133−137 60 Nd, 144−158 64 Gd, [177][178][179][180][181][182][183][184][185][186][187][188][189][190][191][192][193][194][192][193][194][195][196][197][198] Pb parents, coming from three regions of different superdeformations, are studied with respect to the α and heavy cluster decays. The α-decay studies also include the heavier 199−210 Pb nuclei, for reasons of spherical magic shells at Z=82 and N=126. The calculations are made by using the preformed cluster-decay model, and the obtained α-decay half-lives are compared with the available experimental data. Having met with a very good success for the comparisons of α-decay half-lives and in giving the associated known magic or sub-magic closed shell structures of both the parent nuclei and daughter products, the interplay of closed shell effects in the cluster-decay calculations is investigated. The clusterdecay calculations also give the closed shell effects of known spherical magicities, both for the parent and daughter nuclei, and further predict new (deformed) closed shells at Z=72-74 and N=96-104 due to both the stability and instability of Hg and Pb parents against cluster decays. Specifically, a new deformed daughter radioactivity is predicted for various cluster decays of [186][187][188][189][190]195 Pb parents with the best possible measurable cases identified as the 8 Be and 12 C decays of 176,177 Hg and/or 192 Pb parents. The predicted decay half-lives are within the measurable limits of the present experimental methods. The interesting point to note is that the parents with measurable cluster decay rates are normal deformed nuclei at the transition between normal and superdeformation.
Microscopic Predictions for Cluster-Decays
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.
Physical Review C, 2010
The relativistic mean-field (RMF) theory is used to obtain the nuclear matter densities for the double folding procedure used to construct the cluster-daughter potential with M3Y nucleon-nucleon interaction including exchange effects. Following the PCM approach, we have deduced empirically the preformation probability P 0 emp from the experimental data on both the αand exotic cluster-decays, specifically of parents in the trans-lead region having doubly magic 208 Pb or its neighboring nuclei as daughters. Interestingly, the RMF-densities-based nuclear potential supports the concept of preformation for both the α and heavier clusters in radioactive nuclei. P 0 α(emp) for α decays is almost constant (∼10 −2-10 −3) for all the parent nuclei considered here, and P 0 c(emp) for cluster decays of the same parents decrease with the size of clusters emitted from different parents. The results obtained for P 0 c(emp) are reasonable and are within two to three orders of magnitude of the well-accepted phenomenological model of Blendowske-Walliser for light clusters.
Shell closure effects studied via cluster decay in heavy nuclei
Journal of Physics G: Nuclear and Particle Physics, 2008
The effects of shell closure in nuclei via the cluster decay is studied. In this context, we have made use of the Preformed Cluster Model (P CM) of Gupta and collaborators based on the Quantum Mechanical Fragmentation Theory. The key point in the cluster radioactivity is that it involves the interplay of close shell effects of parent and daughter. Small half life for a parent indicates shell stabilized daughter and long half life indicates the stability of the parent against the decay. In the cluster decay of trans lead nuclei observed so far, the end product is doubly magic lead or its neighbors. With this in our mind we have extended the idea of cluster radioactivity. We investigated decay of different nuclei where Zirconium is always taken as a daughter nucleus, which is very well known deformed nucleus. The branching ratio of cluster decay and α-decay is also studied for various nuclei, leading to magic or almost doubly magic daughter nuclei. The calculated cluster decay half-life are in well agreement with the observed data. First time a possibility of cluster decay in 218 U nucleus is predicted.
Cluster decay half-lives of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">mml:mmultiscriptsmml:miBa<mml:mprescripts /><mml:none />mml:mrowmml:mn112mml:mo–mml:mn122 isotopes from the ground state a...
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.
International Journal of Modern Physics E, 2011
Using the preformed cluster model (PCM) of Gupta and collaborators, we have deduced empirically the preformation probability P0emp from experimental data on both the α and exotic-cluster radioactive decays in the trans-lead region having doubly magic 208 Pb or its neighboring nuclei as daughters, using the spherical and (in some cases) deformed relativistic mean field (RMF) densities. For spherical considerations, the P0α(emp) for alpha-decays is almost constant ~ 10-2 - 10-3 for all the parent nuclei studied, and P0c(emp) for cluster-decays of the same parents decrease with increasing size of cluster. The results obtained for spherical P0c(emp) are within two to three orders of magnitude of the well accepted phenomenological formula of Blendowske-Walliser (BW), which led us to propose a new empirical formula. The use of deformed RMF densities, however, tend to bring the results closer to BW formula.
Deformation and orientation effects in heavy-particle radioactivity of Z=115
EPJ Web of Conferences, 2015
The possibility of heavy particle radioactivity (heavier clusters) in ground state decays of 287−289 115 parent nuclei, resulting in a doubly magic daughter around 208 Pb is analyzed using Preformed Cluster Model (PCM) with choices of spherical and quadrupole deformation (β 2 ) having "optimum" orientations of decay products. The behavior of fragmentation potential and preformation probability is investigated in order to extract better picture of the dynamics involved. Interestingly, the potential energy surfaces obtained via the fragmentation process get modi¿ed signi¿cantly with the inclusion of deformation and orientation effects, which in turn inÀuence the preformation factor.