Coulomb And Proximity Potential Model For Deformed Nuclei Research Articles

Theoretical predictions forα-decay chains ofZ=119isotopes in the region274≤A≤313

An extensive study on the \ensuremath{\alpha}-decay half-life for the isotopes of $Z$ = 119 superheavy nuclei in the range 274 \ensuremath{\le} $A$ \ensuremath{\le} 313 is performed within the Coulomb and proximity potential model for deformed nuclei (CPPMDN). We have also evaluated the decay properties by keeping the parents and daughter in spherical nuclear shape (without including the nuclear deformations), within the Coulomb and proximity potential model (CPPM). The half-life calculations are also performed by using the Viola-Seborg semi-empirical (VSS) relation, very frequently used for \ensuremath{\alpha}-decay studies, and it can be seen that our predictions agree well with the computed VSS values. Our intention to understand the mode of decay of the isotopes was fulfilled through the spontaneous fission (SF) half-life calculations and the comparison of the \ensuremath{\alpha} half-lives with the SF half-lives. Thus, our study reveals that those isotopes of $Z$ = 119 with $A$ \ensuremath{\ge} 309 and with $A$ \ensuremath{\le} 275 do not survive fission, and thus, the \ensuremath{\alpha} decay is restricted within the range of 276 \ensuremath{\le} $A$ \ensuremath{\le} 308. Through our study, we have predicted six consistent \ensuremath{\alpha} chains from ${}^{292--295}$119, five consistent \ensuremath{\alpha} chains from ${}^{296}$119, four consistent \ensuremath{\alpha} chains from ${}^{297}$119, and three consistent \ensuremath{\alpha} chains from ${}^{298,299}$119, and we hope these findings will provide a new guide for future experiments. A theoretical study is performed here to understand the mode of decay of the isotopes of $Z$ = 119, which helps to identify the mode of decay of about 40 isotopes within the range of 274 \ensuremath{\le} $A$ \ensuremath{\le} 313.

Systematic studies onα-decay fine structure of odd-odd nuclei in the region83≤Z≤101

A systematic study on \ensuremath{\alpha}-decay fine structure of odd-odd nuclei in the region 83 \ensuremath{\le} $Z$ \ensuremath{\le} 101 has been done using the recently proposed Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed partial half-lives, total half-lives, and branching ratios are compared with the experimental data and they are in good agreement. We have modified the assault frequency and redetermined the half-lives and they show better agreement with the experimental value. Using the new assault frequency, the standard deviations for the half-life and branching ratio are found to be 0.997 and 1.07, respectively, and this implies that CPPMDN is apt for \ensuremath{\alpha}-decay fine-structure study for an entire range of nuclei.

α-decay chains from293,294117 superheavy nuclei

The phenomenon of $\ensuremath{\alpha}$ decay for ${}^{293,294}$117 superheavy nuclei is investigated within the Coulomb and proximity potential model for deformed nuclei (CPPMDN), in order to emphasize the recent experimental works on the element. The computed $\ensuremath{\alpha}$-decay half-lives are in good agreement with the experimental results. It is clear that the values calculated using our formalisms match well with the values computed using the Viola-Seborg systematic, and with the values reported by the generalized density dependent cluster model. The $\ensuremath{\alpha}$-decay calculations have also been performed for the decay chains of ${}^{293,294}$117 nuclei keeping the parents and daughter in spherical nuclear shape. These comparative studies ensure the validity of the CPPMDN.

Fine structure in the α-decay of odd–even nuclei

Systematic study on {\alpha}-decay fine structure is presented for the first time in the case of odd-even nuclei in the range 83 \leq Z \leq 101. The model used for the study is the recently proposed Coulomb and proximity potential model for deformed nuclei (CPPMDN), which employs deformed Coulomb potential, deformed two term proximity potential and centrifugal potential. The computed partial half lives, total half lives and branching ratios are compared with experimental data and are in good agreement. The standard deviation of partial half-life is 1.08 and that for branching ratio is 1.21. Our formalism is also successful in predicting angular momentum hindered and structure hindered transitions. The present study reveals that CPPMDN is a unified theory which is successful in explaining alpha decay from ground and isomeric state; and alpha fine structure of even-even, even-odd and odd-even nuclei. Our study relights that the differences in the parent and daughter surfaces or the changes in the deformation parameters as well as the shell structure of the parent and daughter nuclei, influences the alpha decay probability.

αdecay chains in271−294115 superheavy nuclei

{alpha} decay of {sup 271-294}115 superheavy nuclei is studied using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The predicted {alpha} half-lives of {sup 287}115 and {sup 288}115 nuclei and their decay products are in good agreement with experimental values. Comparison of {alpha} and spontaneous fission half-lives predicts four-{alpha} chains and three-{alpha} chains, respectively, from {sup 287}115 and {sup 288}115 nuclei and are in agreement with experimental observation. Our study predicts two-{alpha} chains from {sup 273,274,289}115, three-{alpha} chains from {sup 275}115, and four-{alpha} chains consistently from {sup 284,285,286}115 nuclei. These observations will be useful for further experimental investigation in this region.

Systematic study on the α-decay fine structure of even–odd nuclei in the range 84 ⩽ Z ⩽ 102

A systematic study on the α-decay fine structure of even–odd nuclei in the range 84 ⩽ Z ⩽ 102 is done for the first time using our recently proposed Coulomb and proximity potential model for deformed nuclei (CPPMDN). The external drifting potential barrier is obtained by the sum of deformed Coulomb potential, deformed two-term proximity potential and centrifugal potential. The computed half-lives and branching ratios are compared with the experimental values. The standard deviation of logarithmic half-lives and branching ratio is 1.25 and 1.10, respectively. Our study reveals that the CPPMDN formalism is also successful in explaining the α-decay fine structure of even–odd nuclei.

αdecay of nuclei in the range67⩽Z⩽91from the ground state and isomeric state

The Coulomb and proximity potential model for deformed nuclei (CPPMDN) is used to study the favored and unfavored $\ensuremath{\alpha}$ decay of nuclei in the range $67$ \ensuremath{\leqslant} $Z$ \ensuremath{\leqslant} $91$ from both the ground state (g.s.) and isomeric state (i.s.). The computed half-lives are in good agreement with experimental data. The standard deviation of half-life is found to be 0.44. Geiger-Nuttall (GN) plots for various parent isotopes are studied. It is found that all four types of transitions (g.s.\ensuremath{\rightarrow}g.s., g.s.\ensuremath{\rightarrow}i.s., i.s.\ensuremath{\rightarrow}g.s., i.s.\ensuremath{\rightarrow}i.s.) lie on a straight line. The isomeric state $\ensuremath{\alpha}$ decay shows a behavior similar to that of the ground state and the nuclear structure of the isomeric states imitates that of the ground states. Some predictions are done for $\ensuremath{\alpha}$ transition from both ground and isomeric states, which will be useful for future experiments.

Alpha decay of even–even nuclei in the region [formula omitted] to the ground state and excited states of daughter nuclei

Alpha half lives, branching ratios and hindrance factors of even–even nuclei in the range 78 ⩽ Z ⩽ 102 from ground state to ground state and ground state to excited states of daughter nuclei are computed using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed half life values and branching ratios are compared with experimental data and they are in good agreement. The standard deviation of half life and branching ratio are 0.79 and 0.94 respectively. It is found that the standard deviation of branching ratio for the ground state to ground state transition is only 0.25 and it increases as we move to the higher excited states which are due to the effect of nuclear structure. It is evident from the study that our ground state decay model is apt for describing not only the ground state to ground state decay but also decay to excited state.