4 research outputs found
Quest for a Universal Cluster Preformation Formula: A new paradigm for estimating the cluster formation energy
This study presents a holistic picture of the preformation of nuclear
clusters with credence to the kinematics of their emissions. Besides the
fitting of the preformation formula to reproduce the experimental half-lives,
we have investigated the interrelationship between the parameters involved in
the cluster decay process for medium, heavy and superheavy nuclei. Based on the
established conceptual findings, we propose a new cluster preformation
probability () formula that incorporates all influential parameters of the
cluster radioactivity and thus has an edge over the existing formulae in the
literature. Further, we hypothesize that a fraction of the decay energy is
needed for cluster formation within the parent nucleus. The proposed formula
opens a new paradigm to separately estimate the energy contributed during the
cluster formation from its emission and thus shows that the contribution of the
Q-value splits into three major parts accounting for the energy contributed
during the cluster preformation, its emission and recoil of the daughter
nucleus. Moreover, the expression is adept at accommodating the theorized
concept of heavy particle radioactivity (HPR). The result reveals that, like
-decay, a proper estimation of the and -value in the cluster
studies are enriched with qualitative information about the nuclear structure.
However, from the analysis, the Geiger-Nuttall law is not the best compromise
in the clustering due to the non-linearity between and
, unlike in -decay. We have demonstrated that with the
inclusion of the proposed formula, the half-life predictions from both
microscopic R3Y and phenomenological M3Y NN potentials closely agree with the
available experimental data and that the slight variation can be traced to
their peculiar barrier characteristics.Comment: 7 pages, 3 figures, Journa
Cluster decay dynamics of Actinides yielding non-Pb-daughter
The cluster dynamics of radioactive nuclei decaying to neighbouring daughter
nuclei of the double magic Sn and Pb is investigated using the
relativistic mean-field (RMF) approach with NL3 parameter set within the
preformed cluster-decay model (PCM). The novel feature of the present study is
the application of the newly derived preformation formula, laying the
groundwork for accessing the break-up of the Q-value: preformation energy,
cluster emission energy and the recoil energy of the daughters formed. The
energy associated with cluster preformation is theoretically quantified for the
first time. This treatment underscores the shell effect, pairing correlation as
well as the blocking of particular orbitals by unpaired nucleons. To ascertain
the applicability of the new formula, the PCM based calculations are carried
out with nuclear potential obtained using the phenomenological M3Y and
microscopic RMF-based R3Y nucleon-nucleon (NN) potentials along with
corresponding densities. We found a marginal variation that can be attributed
to the difference in their barrier properties, however, the predictions for the
case of both M3Y and R3Y potentials are found to agree well with the
experimental half-lives. Although none of the considered reaction systems
yields a double magic daughter nucleus, we found that the kinematics of their
cluster emissions is governed by their proximity to the shell closure. The
deduced systematic of the recoil energy in cluster decays can provide valuable
insight for the synthesis of elements in superheavy mass region in the future.Comment: 10 pages, 5 figures, Journa
Preformation Probability and Kinematics of Clusters Emission yielding Pb-daughters
In the present study, the newly established preformation formula is applied
for the first time to study the kinematics of the cluster emission from various
radioactive nuclei, especially those decaying to the double-shell closure
Pb nucleus and its neighbours as daughters. The recently proposed
universal cluster preformation formula has been established based on the
concepts that underscore the influence of the mass and charge asymmetry
( and ), cluster mass and the Q-value, paving the way to
quantify the energy contribution during the preformation as well as the
tunnelling process separately. The cluster-daughter interaction potential is
obtained by folding the relativistic mean-field (RMF) densities with the
recently developed microscopic R3Y using the NL and the phenomenological
M3Y NN potentials to compare their adaptability. The penetration probabilities
are calculated from the WKB approximation. With the inclusion of the new
preformation probability , the predicted half-lives from the R3Y and M3Y
interactions are in good agreement with the experimental data. Furthermore, a
careful inspection reflects slight differences in the decay half-lives, which
arise from their respective barrier properties. The for the systems with
the double magic shell closure Pb daughter are found to be relatively
higher with an order of than those with neighbouring Pb-daughter
nuclei. By exploring the contributions of the decay energy, the recoil effect
of the daughter nucleus is appraised, unlike several other conjectures. Thus,
the centrality of the Q-value in the decay process is demonstrated and
re-defined within the preformed cluster-decay model. Besides, we have
introduced a simple and intuitive set of criteria that governs the estimation
of recoil energy in the cluster radioactivity.Comment: 09 Pages, 06 Figures, and 01 Tabl
Isotopic Shift in Hg-Isotopes within Brückner versus Relativistic Energy Density Functional
The present study is focused on revealing a characteristic kink of the neutron shell closure N = 126 across the Hg-isotopic chain within the relativistic mean-field (RMF) approach with the IOPB-I, DD-ME2, DD-PC1 and NL3 parameter sets. The RMF densities are converted to their spherical equivalence via the Wood–Saxon approximation and used as input within the parametrization procedure of the coherent density fluctuation model (CDFM). The nuclear matter symmetry energy is calculated using the Brückner energy density functional, and its surface, as well as volume components, are evaluated within Danielwicz’s liquid drop prescription. In addition, a comparison between Brückner and relativistic energy density functionals using the NL3 parameter set is shown as a representative case. The binding energy, charge distribution radius and symmetry energy are used as indicators of the isotopic shift in both ground and isomeric states. We have found the presence of a kink at the shell/sub-shell closure at N = 126 for neutron-rich 206Hg. The formation of the kink is traceable to the early filling of the 1i11/2 orbitals rather than 2g9/2, due to the large spin-orbit splitting. As such, the link between the occupational probability and the magicity of nuclei over the Hg-isotopic chain is established