Study of fragmentation potential for doubly magic

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.

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 '*

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.

Physical Review C, 2009

Based on the preformed cluster model (PCM) of Gupta and collaborators, we have extended our recent study on ground-state cluster decays to parent nuclei resulting in daughters other than spherical 208 Pb, i.e., to deformed daughters, and the very new cases of 14 C and 15 N decays of 223 Ac, and 34 Si decay of 238 U, taking nuclei as spherical, quadrupole deformed (β 2 ) alone, and with higher multipole deformations up to hexadecapole (β 2 , β 3 , β 4 ) together with the "optimum" orientations of cold decay process. Except for 14 C decays of 221 Fr, 221−224,226 Ra, and 225 Ac where higher multipole deformations up to β 4 are found essential, the quadrupole deformation β 2 alone is found good enough to fit the experimental data. Because the PCM treats the cluster-decay process as the tunneling of a preformed cluster, the deformations and orientations of nuclei modify both the preformation probability P 0 and tunneling probability P , and hence the decay half-life, considerably.

Physical Review C, 2013

Production and decay of the isotopes of Hs were studied in the 226 Ra + 48 Ca reaction at beam energies E lab = 229, 234, and 241 MeV. At the E lab = 234 MeV energy, the maximum of the 4n-evaporation channel of the reaction, six identical α-SF decay chains of the nucleus 270 Hs were detected corresponding to a cross section of σ 4n = 16 +13 −7 pb. At the other 48 Ca energies, no Hs isotopes were observed. Nuclei of 270 Hs undergo α decay with a Q α = 9.15 ± 0.08 MeV and the half-life of the daughter spontaneous fission (SF) isotope 266 Sg is 0.28 +0.19 −0.08 s, in good agreement with the data previously observed in the 248 Cm( 26 Mg,4n) 270 Hs reaction. The partial α-decay half-life of 270 Hs was measured for the first time: T α = 7.6 +4.9 −2.2 s. For the spontaneous fission, we determined a lower limit T SF 10 s. Decay properties of 270 Hs corroborate theoretical predictions of its relatively high stability caused by the effect of the deformed shells at Z = 108 and N = 162.

Il Nuovo Cimento A, 1974

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.

We calculated the half-life times (T c) of the 14 C, 20 O, 20 Ne, and 24 Ne cluster emissions from heavy and superheavy nuclei. The variation of T c with the neutron and proton numbers of daughter nuclei is studied to determine the minima in log 10 T c at each neutron number for different daughter isotones. We found that each minimum for a given isotone corresponds to neutron magicity already indicated by other approaches. The proton numbers at neutron magic numbers were found to be also proton magic numbers or differ slightly from them. We arranged the different isotones at each neutron magic number according to their stability in the sense that the more stable daughter isotone corresponds to the lowest value of log 10 T c. The magic neutron numbers predicted by the present study are N = 126, 148, 152, 154, 160, 162, 172, 176, 178, 180, 182, 184, and 200. The predicted magic proton numbers are Z = 82, 98, 100 102, 106, 108, 114, and 116. The values of N and Z mentioned above agree with magic numbers deduced in other studies.

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.

Nuclear physics a, 2022

The alpha decay, the cluster radioactivity and the heavy particle emission half-lives of known and some still unknown superheavy nuclei have been investigated within the original Generalized Liquid Drop Model and analytic formulas. The Q value has been calculated mainly from the recent NUBASE2020 tables. The agreement between the experimental data and the theoretical predictions of the alpha decay half-lives of the superheavy nuclei is correct and some predictions are provided for unknown nuclei. For some emissions of heavy particles by superheavy nuclei the half-life is comparable to the alpha decay half-lives or even smaller.