Two-proton radioactivity within Coulomb and proximity potential model

In the present work, considering the preformation probability of the emitted two protons in the parent nucleus, we extend the Coulomb and proximity potential model (CPPM) to systematically study two-proton (2p) radioactivity half-lives of the nuclei close to proton drip line, while the proximity potential is chosen as Prox.81 proposed by Blocki et al. in 1981. Furthermore, we apply this model to predict the half-lives of possible 2p radioactive candidates whose 2p radioactivity is energetically allowed or observed but not yet quantified in the evaluated nuclear properties table NUBASE2016. The predicted results are in good agreement with those from other theoretical models and empirical formulas, namely the effective liquid drop model (ELDM), generalized liquid drop model (GLDM), Gamow-like model, Sreeja formula and Liu formula.

Recalculated Viola-Seaborg Coefficients for Partial Alpha Half-lives Based on AME2016

In this paper, the systematics for obtaining the Viola-Seaborg formula (VSF) for logarithmic partial alpha half-lives (Tα1/2) have been undertaken based on the NUBASE2016 evaluation. The constants Az and Bz in Geiger-Nuttal law for determination of Tα1/2 , are obtained using gs-gs transitions data, of even-even nuclei for two sets of nuclei with Z = 84 - 102 and Z = 86 - 98 with N > 126. The Viola-Seaborg co-efficients are determined for both the sets. The obtained parameters for both sets are tested on even-even nuclei for Z ranging from 104 - 118 and it is observed that first set parameters fare better. This formula for estimating α-decay half-lives of heavy nuclei can be extrapolated to predict those of super-heavy nuclei. The logarithmic half-lives Tα1/2 obtained for isotopes of Z = 121 and 122 using current modified VSF (AME2016) are compared with those obtained from theoretical considerations using Coulomb and proximity potential model (CPPM) and observed to be much larger. They are also much larger than those obtained from the previous coefficients based on AME2003 data.

Theoretical cluster decay predictions for the nuclei 245−260Md with different nuclear potentials

We have studied systematically the alpha decay and cluster radioactivity half-life of heavy [Formula: see text]Mendelevium ([Formula: see text]) isotopes. The alpha decays from Md isotopes have been studied within the framework of Coulomb and proximity potential model using 14 different versions of nuclear potentials. Also, we have studied the half-lives of alpha decay of Md nuclei within the nuclear potentials generalized liquid drop model (GLDM) and also within GLDM with modified different nuclear potentials, namely proximity potential 2010, 1977, 1988, 2000 and 2002. Moreover, the half-lives of the [Formula: see text]-decay and cluster radioactivity calculated using the Universal formula for cluster decay (UNIV) of Poenaru et al., the Universal decay law (UDL) of Qi et al. and the Unified formula of half-lives for both the [Formula: see text]-decay and cluster radioactivity (UFADCR) of Ni et al. and found to be in good agreement. Our results have been compared with experimental data and demonstrate the acceptability of the approach. Among the different proximity potentials, GLDM with proximity 1977 version (GLDM[Formula: see text][Formula: see text][Formula: see text]P77) ([Formula: see text]) provides the best description for alpha decay studies with low deviation.

Alpha decay half-lives of 171-189Hg isotopes using Modified Gamow-like model and temperature dependent proximity potential

The alpha decay half-lives for $^{171-189}\mathrm{Hg}$ isotopes have been computed using the Gamow-like model (GLM), modified Gamow-like model (MGLM1), temperature-independent Coulomb and proximity potential model (CPPM), and temperature-dependent Coulomb and proximity potential model (CPPMT). New variable parameter sets were numerically calculated for the $^{171-189}\mathrm{Hg}$ using the modified Gamow-like model (termed MGLM2). The results of the computed standard deviation indicates that the modified Gamow-like model (MGLM2) and the temperature-dependent Coulomb and proximity potential model give the least deviation from available experimental values, and therefore suggests that the two models (MGLM2 and CPPMT) are the most suitable for the evaluation of $\alpha$-decay half-lives for the $\mathrm{Hg}$ isotopes.

Theoretical Study on the Formation of 1-neutron and 2-neutron Halo Nuclei via Decay of Elements in Super-Heavy Region

The possibility for the existence of 1-neutron and 2-neutron halo nuclei through the decay of even-even nuclei 270-316116, 272-318118 and 278-320120 in the super-heavy region is studied within the frame work of the Coulomb and Proximity Potential Model (CPPM). Halo structure in neutron rich nuclei with Z<=20 is identified by calculating the neutron separation energies and on the basis of potential energy considerations. The 1n + core configuration of proposed 1-neutron halo nuclei between z=10 and Z=20 is found shifted to 2n + core configuration in higher angular momentum states. The calculation of half-life of decay is performed by considering the proposed halo nuclei as spherical cluster and as deformed nuclei with a rms radius. Except for 15C, the half-life of decay is found decreased when the rms radius is considered. Only the 1-neutron halo nuclei 26F and 55Ca showed half-lives of decay which are less than the experimental limit. None of the proposed 2-neutron halo nuclei have shown a half-life of decay lower than the experimental limit. Also, the probability for the emission of neutron halo nuclei is found to be less in super-heavy region when compared with the clusters of same isotope family. Further, neutron shell closure at neutron numbers 150, 164 and 184 is identified form the plot of log10 T1/2 verses the neutron number of parents. The plots of Q-1/2 verses log10 T1/2 and -ln P verses log10 T1/2 for various halo nuclei emitted from the super-heavy elements are found to be linear showing that Geiger-Nuttall law is applicable to the emission of neutron halo also.

Competition between decay modes of superheavy nuclei 281−310Og

In this work, we have made an attempt to study the cluster-decay half-lives and alpha-decay half-lives of the superheavy nuclei [Formula: see text]Og by considering the temperature-dependent (TD) and also temperature-independent (TID) proximity potential model. The evaluated half-lives were compared with that of the experiments. To predict the decay modes, we have compared the cluster-decay half-lives and alpha-decay half-lives with that of spontaneous fission half-lives. This work also predicts the decay chains of the superheavy nuclei [Formula: see text]Og and finds an importance in the synthesis of further isotopes of superheavy element Oganesson.

A systematic study on α-decay chains of superheavy nuclei, Z = 126 & 138

The [Formula: see text]-decay chain of [Formula: see text] and [Formula: see text] is studied using cubic plus proximity potential with improved transfer matrix (CPP-ITM) model. The nuclear mass models DD-PC1, WS4, WS3.3 are employed to evaluate the [Formula: see text]-decay energies. Thus calculated [Formula: see text]-decay half-lives and decay chain lengths are found to be in good agreement with other theoretical formalisms. The spontaneous fission (SF) half-lives are calculated using the formalism of Xu et al. [Phys. Rev. C 71 (2005) 014309; Phys. Rev. C 78 (2008) 044329] to have a vision on the possible decay modes and decay chain lengths, and the most probable decay chains associated with the isotopes of [Formula: see text] [Formula: see text] [Formula: see text]. This paper unveils the mass region that survives fission and also predict the long [Formula: see text]-decay chains of [Formula: see text] [Formula: see text] [Formula: see text] with [Formula: see text] emitting 6[Formula: see text], [Formula: see text] emit 5[Formula: see text] [Formula: see text] [Formula: see text] 4[Formula: see text] particles, while for [Formula: see text] chains will have [Formula: see text] emission. The SF for [Formula: see text] [Formula: see text] [Formula: see text] occur at [Formula: see text] and [Formula: see text]. These current predictions may pave way to detect/synthesize the most probable isotopes of the superheavy elements [Formula: see text] [Formula: see text] [Formula: see text] in the laboratory through future experiments.

Investigations on the superheavy nuclei with magic number of neutrons and protons

It was recognized that the magic numbers of nuclei 2, 20, 28, 50, 82 and 126 are predicted to be more stable than the neighbor nuclei. Later on the researchers predicted that the magic numbers for protons are 114, 122, 124 and 164 and the magic numbers for neutrons are 184, 196, 236 and 318. The predicted second generation magic number for proton and neutron comes in the superheavy nuclei region. The superheavy nuclei with magic number of protons/neutrons are [Formula: see text]114, [Formula: see text]114, [Formula: see text]122, [Formula: see text]122, [Formula: see text]124, [Formula: see text]124, [Formula: see text]126 and [Formula: see text]126. All the possible decay modes have been studied by using three different models such as modified generalized liquid drop model, dynamical cluster model and coulomb-proximity potential model. In the second part of this study, we have made detailed investigations to synthesize the above said nuclei using fusion reactions with modified Woods–Saxon potential model. This study also identifies the most possible projectile target combinations for the synthesis of the predicted magic nuclei in the superheavy nuclei region.