Dynamical Cluster-decay Model Research Articles

Investigation of decay mechanisms and associated aspects of exotic Nobeliumisotopes using the Skyrme energy density formalism

Abstract Persistent theoretical and experimental attempts have been made to investigate the
heavy ion induced reactions and their subsequent decay mechanisms in superheavy mass region.
In addition, the region of transfermium elements is itself of great interest because of the neutron
/ proton shell effects. Here, we aim to study the subsequent decay mechanisms of two isotopes of
Z = 102 nucleus, i.e. 248No and 250No.
The dynamical cluster-decay model (DCM) based on Quantum Mechanical Fragmen-
tation Theory (QMFT), is employed to conduct a comprehensive analysis of compound nucleus
(CN) and non-compound nucleus (nCN) mechanisms such as fusion-fission (ff), Quasi fission (QF)
and fast fission (FF), the role of centre of mass energy (Ec.m.) and angular momentum (ℓ) for
248No and 250No isotopes. The nuclear interaction potential is obtained using the Skyrme energy
density formalism (SEDF) in the domain of GSkI force parameters. The probability of compound nucleus formation
(PCN ) is determined using a function that depends on the centre of mass energy. The lifetimes for
the fusion-fission (ff) quasi fission (QF) channels are explored.
Here, CN and nCN decay mechanisms for two isotopes of Z = 102 nobelium are studied
over the wide range of centre-of-mass (Ec.m.) by including the quadrupole deformation (β2) and
optimum orientations (θopt.) of decaying fragments. The fragmentation potential, preformation
probability, neck length parameter and reaction cross-sections are explored. Further, the calcula-
tions are done for PCN in order to identify the decay modes of 248No and 250No isotopes. The
fusion-fission lifetimes and quasi fission lifetimes are compared with the dinuclear system (DNS)
approach. The most probable fragments such as 122Sn and 128T e are observed near to the magic shell closure Z = 50 and
N = 82. The ff and qf lifetime decreases with increase in the excitation energy.

Exploring asymmetric fission in 180Hg⁎ compound nucleus using dynamical cluster-decay model

The observed asymmetric fission of the 180Hg⁎ compound nucleus challenges conventional expectations of symmetric fission, which are attributed to the presence of shell closures at Z=40 (semi-magic) and N=50 (magic). To comprehend this novel phenomenon, the dynamical cluster-decay model has been employed. For the first time, this model incorporates the bulk and neutron-proton asymmetry coefficients of the nuclear shape-dependent mass excess formula which are tuned recently to the ground state mass excess data of AME2020 and/or FRDM(2012) along with the temperature dependence for the nuclear shape and the surface energy coefficient of the nuclear proximity potential. The calculations have considered nuclear shapes as both spherical and deformed (quadrupole), with and without temperature dependence for the quadrupole deformation. A new minimum appears in the symmetric mass region of the fragmentation potential for masses (80, 100), when the fragments are deformed and optimally oriented, at an energy lower than that obtained for masses (90, 90) where the fragments are assumed to be spherical or nearly spherical at higher temperatures. This new minimum seems equivalent to the appearance of a new shell gap with deformation and is responsible for the asymmetric fission of 180Hg⁎. The most probable fission channel and the transition from asymmetric to symmetric mass distribution at higher excitation energies are consistent with experiments for the current temperature dependence assigned to the quadrupole deformation parameter.

Exploring fission and quasi-fission in 31Al + 197Au: probing energies near and beyond Coulomb barrier

An idea to understand the fragmentation of a formed nuclear entity (i.e. compound nucleus), induced via heavy-ion reactions, is an interesting task especially at incident energies near, above and far away from the Coulomb barrier. In the present work, we are studying the decay dynamics of a formed nuclear entity i.e. 228U* compound nucleus (CN), via the radioactive beam of Aluminium-31 (31Al) striking on the stable Gold-197 (197Au) target nucleus, for incident energies E c.m. = 106.2–163.2 MeV. A comprehensive knowledge regarding the probable decaying fragments from 228U* has been accumulated using the collective clusterization approach of the Dynamical Cluster-decay Model (DCM) in terms of mass and charge dispersion, which built up on the Quantum Mechanical Fragmentation Theory (QMFT). Through both of these dispersion cases, we have identified the decaying fragments in the fission and heavy-mass regions, at different scale of incident energies. Further, the fission cross-sections ( σfisTheo ) have been obtained for 31Al + 197Au → 228U* reaction at the above said E c.m. (MeV) and compared with the experimental data. This study has been carried out using two different sets of Skyrme force parameters (SIII and SSk), which are employed within the semiclassical approach of Skyrme Energy Density Formalism. Unlike for energies below and near the barrier, a significant difference has been observed between calculated ( σfisTheo ) and experimental ( σfisExpt ) cross-sections for above barrier energies, with independent choice of Skyrme forces. Such discrepancy noticed has been addressed with the presence of quasi-fission (QF) event. Similar phenomena has also been seen for 19F-induced reaction forming the same CN (228U*).

Alpha clustering in 41, 45, 49Ca* nuclei formed in neutron induced reactions

The light neutron-rich nuclei play a vital role in nucleosynthesis process and the extent of alpha (α) clustering significantly influence the astrophysical rates. Thus, it is significant to explore the α clustering in these nuclei and in the present work, we have studied the α clustering in 41,45,49Ca* nuclei formed in neutron induced reactions within the dynamical cluster decay model (DCM). The results present that with progression towards neutron-rich 45Ca* and 49Ca* nuclei, there is a significant decrease in the α-cluster preformation factor P0. The inclusion of relativistic mean field theory (RMFT) based microscopic temperature-dependent binding energies (T.B.E.) within DCM, give relatively enhanced α-cluster preformation factor for 41,45,49Ca* nuclei compared to the case of macroscopic T.B.E. based upon Davidson mass formula. The cross-section associated with α-cluster emission depicts strong isospin dependence and falls off significantly with increasing neutron number of Ca* nuclei. Further, for the first time, we inculcate the microscopic nuclear potential constructed via folding the standard Fermi form fitted RMFT cluster densities and M3Y nucleon-nucleon interaction within the DCM. The neutron skin thickness of the Ar cluster, complementary to α-cluster, is varied and its effect upon the nuclear interaction potential and α-cluster preformation factor is analysed. The results present that with growing neutron skin of Ar cluster, the α-cluster preformation factor decreases. It explores a strong correlation among the neutron skin thickness and α-cluster preformation factor in light mass 41,45,49Ca* nuclear systems.

Comparative studies of α-decay channel from 144Nd* and 148Sm* populated via neutron induced reactions

A comparative study of α-decay channel from the composite systems 144Nd* and 148Sm* populated via n-induced reactions- n+143Nd and n+147Sm, is done at Ebeam=5.0 MeV. The study proceeds through the Dynamical Cluster-decay Model (DCM) as suggested by an experiment performed by Gledenov et al. at Peking University, China. An attempt is made to do a theoretical investigation of decay profiles of 144Nd* and 148Sm* to analyze the effect of temperature, neck-length and angular momentum state of the hot-rotating system at common beam energy. The results are exhibited in the form of variations in fragmentation structure and the barrier modification effects that are illustrated from the barrier penetration profiles. Additionally, a competing analysis of light charge particle emission is done where the cumulative contribution of α-emission towards the decay channel is depicted in contrast to the contribution from other light particles (n, 2n,3n) or light charged particles (3H) for both the decaying systems 144Nd* and 148Sm*.

Exploring Isotope Production through 2n-Emission in Reactions Induced by 48Ca: A Theoretical Investigation

In this investigation, we employ the Dynamical Cluster-decay Model (DCM) approach to scrutinize the fragmentation channels emerging from 245Es* and 251Md*. These nuclei are produced through 48Ca+197Au and 48Ca+203Tl reactions with similar beam energies of approximately 210.0 MeV and 212.7 MeV. This methodology involves adjusting the neck formation (ΔR) within the DCM framework to compute 2n-emission cross-sections for these systems. These calculated cross-sections are then juxtaposed against experimental data to validate the predictive capabilities of the model. Furthermore, this study examines the fragmentation dynamics of fragments emerging from 245Es* and 251Md*, investigating its characteristics based on minimized coordinates of the lighter fragment’s mass (A2). This analysis is performed at the most suitable ΔR values, elucidating the energetically favoured decay pathways and the potential presence of magic or near magic shell closures. Moreover, this investigation delves into the preformation and penetration probabilities associated with 2n-emission and their dependence upon the angular momentum values involved. As an extension of this work, a comparative evaluation of 1n-emission from both 245Es* and 251Md* is also carried out in terms of variations in preformation probabilities and penetration probabilities. Notably, these results underscore the necessity for experimental validation of the DCM-predicted 1n-emission data, enhancing the credibility and robustness of the model’s predictions.

Fusion enhancement within a collective clusterization approach applied to the isotopic chain of neutron-rich light-mass compound nuclei

The dynamics of neutron-rich light-mass compound nuclei $^{24,25,26,27}\mathrm{Mg}^{*}$ formed in $^{12,13,14,15}\mathrm{C}+^{12}\mathrm{C}$ fusion reactions, respectively, is explored at different ${E}_{\mathrm{c}.\mathrm{m}.}$ values within the dynamical cluster decay model (DCM). DCM is based on the quantum mechanical fragmentation theory, which treats the binary fragmentation of emitting compound nucleus as light particles (LPs), intermediate mass fragments (IMFs), as well as symmetric mass fragments (SMFs), on equal footing, which is not the case with other fission and statistical models. All calculations are made for spherical considerations and angular momenta taken up to the $\ensuremath{\ell}$-critical value for the respective reactions. A fusion enhancement is observed as we go from compound nuclei (CN) having an even number of neutrons ($^{24,26}\mathrm{Mg}^{*}$) to CN with the odd number of neutrons ($^{25,27}\mathrm{Mg}^{*}$). Interestingly, we find that the only parameter of the DCM, the neck-length parameter $\mathrm{\ensuremath{\Delta}}R$ related to the barrier lowering, is in linear relation with ${\ensuremath{\sigma}}_{\mathrm{Fusion}}$ at chosen incident laboratory energy. The fusion enhancement is found to be larger for odd neutron number nuclei, which indicates the influence of unpaired neutrons on fusion cross sections. Within the formalism of DCM, the phenomenon of fusion enhancement finds its base in the process of collective clusterization, which is quite evident from the larger values of summed-up preformation probability for the reactions having odd mass projectiles or forming odd mass CN. The DCM calculated fusion cross sections are in good agreement with the available experimental data for the given reactions.

Systematic analysis of the decay of Fl*287,288,290,292 formed in the complete fusion reactions Pu239,240,242,244+Ca48 including Skyrme forces

The fusion evaporation residue cross sections for the decay of the compound nuclear system $^{287,288,290,292}\mathrm{Fl}^{*}$ via $2n$- to $5n$-decay channels, synthesized in $^{239,240,242,244}\mathrm{Pu}+^{48}\mathrm{Ca}$, are studied using the dynamical cluster-decay model (DCM), including quadrupole deformations ${\ensuremath{\beta}}_{2i}$ for compact hot orientations ${\ensuremath{\theta}}_{i}$ at various excitation energies ${E}^{*}=32.5$ to 52.6 MeV. For the nucleus-nucleus interaction potentials, we have employed the Skyrme energy density functional based on the semiclassical extended Thomas-Fermi approach under frozen density approximation. Here, within the DCM, the Skyrme forces used are SLy4, ${\mathrm{SkM}}^{*}$, and, KDE0(v1). The DCM makes use of a single parameter, the neck-length parameter $\mathrm{\ensuremath{\Delta}}R$ that takes different values for different processes at a given temperature and provides an excellent fit to the measured data, independently of the choice of Skyrme force used. We make predictions of probable fusion-fission and quasifission mass regions of fragments and then calculate the evaporation residue cross sections ${\ensuremath{\sigma}}_{\mathrm{ER}}$ for experimentally unobserved neutron channels. Further, the product ${P}_{\mathrm{CN}}{P}_{\mathrm{surv}}$ of compound nucleus (CN) fusion probability ${P}_{\mathrm{CN}}$ and survival probability ${P}_{\mathrm{surv}}$ is calculated to determine the reduced evaporation residue cross section ${\ensuremath{\sigma}}_{\mathrm{ER}}/{\ensuremath{\sigma}}_{\mathrm{fusion}}$, denoted as ${\ensuremath{\sigma}}_{\mathrm{ER}}^{\mathrm{reduced}}$, and we have seen that ${P}_{\mathrm{surv}}$ is the main dominant factor in the product ${P}_{\mathrm{CN}}{P}_{\mathrm{surv}}$. To this end, we have analyzed the effects of mass asymmetry and isospin effect of target nucleus on the ${\ensuremath{\sigma}}_{\mathrm{ER}}$ and have found that the ${\ensuremath{\sigma}}_{\mathrm{ER}}$ for the production of superheavy element ${\mathrm{Fl}}^{*}$ increases slowly with increasing neutron number of the target nucleus. We have also searched for all possible target-projectile combinations forming the hot compound nucleus ${\mathrm{Fl}}^{*}$ at the excitation energy ${E}^{*}$ for compact-hot configurations and have also calculated the fusion evaporation residue cross sections for the proposed new reactions synthesizing Fl.

Fission decay modes of 254Fm* compound nucleus formed in 16O+238U reaction

The quantum mechanical fragmentation theory (QMFT) based dynamical cluster-decay model (DCM) is applied to analyze the probable fission decay modes of 254Fm* compound nucleus produced in 16O+238U nuclear reaction at excitation energy EC*N =45.9 MeV. The fission valley of collective fragmentation potential and the multi-humped peaks of preformation probability P0 profile are analyzed by considering compact as well as elongated configurations of quadrupole (β2) deformed fragments. The competitive emergence of different symmetric [symmetric superlong (SL), symmetric supershort (SS)] and asymmetric [standard 1 (S1), standard 2 (S2), standard 3 (S3)] fission modes have been observed for the case of elongated configuration. The division of mass and charge in nuclear fission of 254Fm* depicts the importance of spherical and deformed magic shell closures. The most energetic light (AL and heavy (AH) decay fragments of aforementioned fission modes are identified. Moreover, the DCM-calculated fission cross-sections (σ fission) show reasonable agreement with the experimental measurements [24].

Fusion-fission analysis of C12+Cm248 and O16+Pu244 nuclear reactions across the Coulomb barrier

By using the symmetric-asymmetric Gaussian barrier distribution (SAGBD) model, Wong formula, and coupled channel approach, heavy ion fusion dynamics is investigated for $^{12}\mathrm{C}+^{248}\mathrm{Cm}$ and $^{16}\mathrm{O}+^{244}\mathrm{Pu}$ reactions at energies lying below and near the Coulomb barrier. Coupling of various channels linked with the structure of participants to the relative motion of the collision partners is done by considering a Gaussian type of weight function in the SAGBD model and cross sections are found to be enhanced relative to the calculations obtained by the simple barrier penetration model. In the SAGBD model, the channel coupling effects are calculated in terms of channel coupling parameter ($\ensuremath{\lambda}$) and percentage reduction in the height of apparent fusion barrier with respect to the Coulomb barrier (${V}_{\mathrm{CBRED}}$). The channel coupling parameter estimates the cumulative influence of dominant intrinsic channels, which are responsible for the sub-barrier fusion enhancement. The SAGBD calculations appropriately explain the dynamics of $^{12}\mathrm{C}+^{248}\mathrm{Cm}$ and $^{16}\mathrm{O}+^{244}\mathrm{Pu}$ reactions at energies lying around the Coulomb barrier. The coupled channel analysis of the present reactions is done by using the code ccfull and the coupled channel calculations unambiguously identify the dominant influences of the rotational states up to ${10}^{+}$ spin states of the ground state rotational band of target isotopes in both reactions. In addition, the couplings to higher order deformation, such as ${\ensuremath{\beta}}_{4}$ for target and low lying quantum states of the projectile, are necessarily required to reproduce the experimental data of $^{12}\mathrm{C}+^{248}\mathrm{Cm}$ and $^{16}\mathrm{O}+^{244}\mathrm{Pu}$ reactions. Apart from the fusion analysis, the dynamical cluster-decay model (DCM) is applied to understand the fission dynamics of the $^{260}\mathrm{No}^{*}$ nucleus formed via the above-mentioned reactions. The decay study is carried out at the center-of-mass energies spread, ${E}_{\mathrm{c}.\mathrm{m}.}$ ($\ensuremath{\approx}79$ to 109 MeV) by including the quadrupole deformations (${\ensuremath{\beta}}_{2}$) and optimum orientations (${\ensuremath{\theta}}_{i}^{\mathrm{opt}}$) of the decaying fragments. According to the experimental observation, the noncompound nucleus (nCN) fission component competes with the compound nucleus (CN) fission processes. Consequently, the possibility of nCN contribution is also explored in the decay of the $^{260}\mathrm{No}^{*}$ compound nucleus. With an aim to have a comprehensive analysis of CN and nCN fission mechanisms, the role of the center-of-mass energy (${E}_{\mathrm{c}.\mathrm{m}.}$) and angular momentum ($\ensuremath{\ell}$) is explored in terms of various parameters of DCM such as fragmentation potential, preformation probability, barrier modification, etc.

A theoretical study on the impact of centrifugal potential and fragment identification in the decay of compound nuclei (ACN = 60&100)

Decay analysis of compound nuclei such as [Formula: see text] and [Formula: see text] formed in [Formula: see text]Ca and [Formula: see text]Ni reactions, respectively, is studied using two theoretical frameworks, dynamical cluster-decay model (DCM) and PACE4. To explore the decay dynamics in a relatively lighter mass region [Formula: see text], two more reactions are picked (i) [Formula: see text]Mg forming the [Formula: see text] compound nucleus, (ii) another one involving the odd mass projectile, [Formula: see text]. In DCM, the fusion excitation functions are calculated using sticking [Formula: see text] and nonsticking [Formula: see text] limits of the moment of inertia. For the chosen reactions, fusion cross-sections are equivalent to evaporation residue (ER) cross-sections [Formula: see text] as fission cross-sections are negligible. A lower magnitude of maximum angular momentum [Formula: see text] is obtained via the [Formula: see text] approach in comparison to the [Formula: see text] approach and the angular momentum obtained via the [Formula: see text] approach is closer to the experimental observations. The structure and magnitude of fragmentation potential and preformation probability [Formula: see text] depend on the choice of moment of inertia and the magnitude of angular momentum involved. Besides this, PACE4 is employed to address the fusion cross-section of chosen reactions. The most probable decay channel is identified using both DCM and PACE4 approaches.

Analysis of formation and decay of Ba*122,128 formed via Ni58,64+Ni64 reactions near the Coulomb barrier

The fusion mechanics of $^{58}\mathrm{Ni}+^{64}\mathrm{Ni}$ and $^{64}\mathrm{Ni} +^{64}\mathrm{Ni}$ reactions is analyzed by using the energy dependent Woods-Saxon potential (EDWSP) model and the subsequent decay dynamics of $^{122}\mathrm{Ba}^{*}$ and $^{128}\mathrm{Ba}^{*}$ isotopes formed in these fusion channels is examined via the dynamical cluster-decay model (DCM). In the EDWSP model, the energy dependent nature of the Woods-Saxon potential causes modifications in the profile of the fusion barrier between fusing nuclei. Such barrier modifications lead to the lowering of the effective fusion barrier of the colliding nuclei. Hence, EDWSP outcomes satisfactorily describe the energy dependence of fusion cross sections of the chosen reactions in near- and sub-barrier energy regions. Following this, the fragmentation of compound nuclei $^{122}\mathrm{Ba}^{*}$ and $^{128}\mathrm{Ba}^{*}$ formed using the above-mentioned reactions is investigated by using the collective clusterization approach of DCM. The calculations are done for quadrupole $({\ensuremath{\beta}}_{2})$ choice of fragmentation with hot configurations having optimized orientations. The evaporation residues' cross-section data lying within beam energy $({E}_{\mathrm{beam}})$ = 171--220 MeV are nicely addressed. The comparative analysis of decaying $^{122}\mathrm{Ba}^{*}$ and $^{128}\mathrm{Ba}^{*}$ nuclei is worked out in terms of fragmentation potential and preformation probability, along with the investigation of barrier characteristics.

Theoretical attempt to predict the cross sections in the case of new superheavy elements

For the first time, within the framework of the dynamical cluster-decay model (DCM) by Gupta and collaborators, we provide reasonable estimations for cross sections of nuclear systems which will give rise to new superheavy elements. The important point and the new approach presented in this contribution are the theoretical calculations done without tracking any reference to experimental data; i.e., these are independent calculations. We will provide a method for reasonable estimates for the cross sections of unobserved possible decay channels in a nuclear reaction. We will demonstrate the capability of the DCM to give a probable/sensible range of the cross section. This exercise of theoretical calculations within the DCM may benefit experiments for the discovery of new superheavy elements. Our results can provide hints to the experimentalist to choose proper incoming channels in order to perform experiments. We have applied this new strategy to calculate the cross sections of the already studied compound nuclei $Z=116$ and 118 via hot fusion reactions, and observed that our calculated range of cross sections has given values within the reach of experimental studies. Both compound nuclei were studied earlier by one of the authors for the angle $\mathrm{\ensuremath{\Phi}}={0}^{\ensuremath{\circ}}$, including quadrupole deformations, ${\ensuremath{\beta}}_{2i}$ alone with ``optimum'' orientations (${\ensuremath{\theta}}_{\mathrm{opt}.}$). Here, we consider the same specifications in order to study the new approach using the DCM. The principal aim of this work is to study the capability of the DCM to determine the cross sections for new elements, where experimental data are not available.

Angular momentum effects on the decay modes of hot compound nuclei formed in 86Kr+134,138Ba reactions

The dependence of decay modes of hot compound nuclei formed in [Formula: see text]Kr[Formula: see text]Ba reactions on the angular momentum has been analyzed using the dynamical cluster-decay model. This has been done by analyzing the change of fragmentation potential, preformation probability, penetrability and cross-section as a function of the fragment mass number at various values of the angular momentum. The evaporation residue cross-section calculated using dynamical cluster-decay model has been compared with the measured one for the channels: [Formula: see text], [Formula: see text], [Formula: see text] for the decay of [Formula: see text]U[Formula: see text] and [Formula: see text] for [Formula: see text]U[Formula: see text]. The summed up fragment cross-sections for the light particles, intermediate mass fragments and fission fragments as a function of angular momentum have been studied which gives an idea for the change of reaction mechanism with angular momentum. The charge distribution of the fission fragment cross-section shows an odd–even staggering, i.e., the probability of even-Z fission fragments is relatively higher than others. The mass distributions obtained within the dynamical cluster-decay model for the decay of [Formula: see text]U[Formula: see text] are in conformity with mass distributions determined by means of the double kinetic-energy technique in literature. The position of the most probable channel has been found to be fixed to a constant atomic number instead of mass number.

Investigation of octupole deformed fragments decaying from even-even isotopes of Th*222–230

Background: In earlier studies, spherical and quadrupole deformed nuclei with closed shells were found to be the most probable fission fragments in the decay of heavy-mass compound nuclei at low excitation energies. Recently, the disintegration of heavy-mass actinides gave evidence of pear-shaped fission fragments, in the mass-asymmetric region, due to extra stability provided by the shell-stabilized octupole deformed $^{144}\mathrm{Ba}$ $(Z=56)$ nucleus.Purpose: In our theoretical work, we have done an exercise to analyze the possibility of octupole deformed fragments in the decay of light- and heavy-mass isotopes of thorium, i.e., $^{222,224,226,228,230}\mathrm{Th}^{*}$.Method: To carry forward the above idea, the mass and charge dispersions of chosen Th isotopes have been analyzed by including deformations (up to ${\ensuremath{\beta}}_{3}$) and related cold optimum orientations within the dynamical cluster-decay model (DCM), which is based on the collective clusterization approach of quantum mechanical fragmentation theory. The above analysis is worked out at low excitation energy, which corresponds to the cold synthesis criteria.Results: In the decay of considered Th isotopes, the minima of fragmentation potential and peaks of preformation probability appear in two regions, near symmetric and asymmetric, respectively due to the presence of quadrupole (${\ensuremath{\beta}}_{2}$) and octupole deformations (${\ensuremath{\beta}}_{3}$) of decay fragments. However, the emission of ${\ensuremath{\beta}}_{3}$-deformed fission fragments is prominent in the heavier isotopes of Th, i.e., $^{226,228,230}\mathrm{Th}^{*}$. The above result is in agreement with the experimentally obtained mass and charge distributions.Conclusions: The disintegration of thorium isotopes into octupole deformed fragments in the asymmetric region signifies their relative stability, which is enhanced for $^{144}\mathrm{Ba}$ ($Z=56$) or in its vicinity.

Theoretical study of evaporation residue cross sections in the decay of Cn*286 formed via the U238+Ca48 reaction using Skyrme forces

The dynamical cluster-decay model (DCM) is employed to study the excitation functions and fusion evaporation residue (ER) cross sections for the production of $^{283}\mathrm{Cn}$ and $^{282}\mathrm{Cn}$ isotopes via $3n$ and $4n$ decay channels from the $^{286}\mathrm{Cn}^{*}$ compound nucleus. The study includes quadrupole deformation ${\ensuremath{\beta}}_{2i}$ and hot-optimum orientations ${\ensuremath{\theta}}_{i}$ at various $^{48}\mathrm{Ca}$-beam energies ${E}_{\mathrm{lab}}=233.3\text{--}240\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ (equivalently, excitation energies ${E}^{*}=34.4\text{--}39.8\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$), supporting symmetric fission, which agrees well with the experimental data. The reaction was investigated by using a hot compact configuration. The Skyrme forces used are new forces GSkI and KDE0(v1), and the conventional force SIII. Apparently, the DCM with the pocket formula for nuclear proximity potential reproduces the measured data on fusion ER nicely within single-parameter fitting of $\mathrm{\ensuremath{\Delta}}R$, independently of the nuclear interaction potential and Skyrme force used. We have also calculated the fusion-fission cross section (${\ensuremath{\sigma}}_{ff}^{\mathrm{predicted}}$) at ${E}^{*}=35\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ and ER cross sections for the experimentally unobserved neutron emission channels $1n$, $2n$, and $4n$ at different excitation energies ${E}^{*}$. Further, we have proposed new target-projectile (t-p) combinations for the synthesis of $^{286}\mathrm{Cn}$ for future experiments.

Possibility to form Z=120 via the Ni64+U238 reaction using the dynamical cluster-decay model

According to different theoretical studies, the next magicity for the proton number should occur at $Z=114$, 120, or 126 and for the neutron number $N=184$. Superheavy nuclei of interest for the forthcoming synthesis of the isotopes with $Z=119$, 120 are investigated. Many reactions have yet to be studied in order to find the possible incoming channels for the formation of $Z=120$. In this work, synthesis of superheavy element 120 in terms of the fission and quasifission cross sections via $^{64}\mathrm{Ni}+^{238}\mathrm{U}$ reaction is evaluated and discussed. We have explored the possibility of formation of $Z=120$ via $^{64}\mathrm{Ni}+^{238}\mathrm{U}$ reaction, using the experimental data from Kozulin , Phys. Lett. B 686, 227 (2010). Some experimental efforts have been made to synthesize $^{302}120$, via Ni-induced and Cr-induced reaction, i.e., $^{64}\mathrm{Ni}+^{238}\mathrm{U}$ reaction at five ${E}^{*}$'s (excitation energies) and the $^{54}\mathrm{Cr}+^{248}\mathrm{Cm}$ reaction at only one energy, respectively. In this work, we have studied the Ni-induced reaction at given energies by including higher multipole deformations ${\ensuremath{\beta}}_{\ensuremath{\lambda}i}$ $(\ensuremath{\lambda}=2,3,4$; $i=1,2)$, and compact orientations ${\ensuremath{\theta}}_{ci}$ using the coplanar degree of freedom $(\mathrm{\ensuremath{\Phi}}={0}^{\ensuremath{\circ}})$ within the framework of the dynamical cluster-decay model (DCM). The neck-length parameter is the only one, which is fixed in reference to the observed data for fission cross section $({\ensuremath{\sigma}}_{\mathrm{ff}})$ calculated for mass region $A/2\ifmmode\pm\else\textpm\fi{}20$, and quasifission cross section $({\ensuremath{\sigma}}_{\mathrm{qf}})$ for the incoming channel of $^{64}\mathrm{Ni}+^{238}\mathrm{U}$ reaction. Our calculations for Ni-induced reaction have shown a good concurrence with the experimental data for quasifission and fission cross sections along with the DCM-calculated estimated and predicted cross sections for evaporation residues (ERs), which can be used for future references. Our results demonstrate the insignificant compound nucleus formation possibility ${P}_{\text{CN}}$ $(\ensuremath{\ll}1)$ for $Z=120$ from Ni-induced reaction because of the very low order of evaporation residues; thus, this work is not supporting this incoming channel for the formation of $Z=120$.

Decay analysis of 24,25Mg⁎ compound nuclei

In the present work, the clustering effects on the reaction dynamics of compound systems 24,25Mg⁎ formed via respective entrance channels C12+12C and C13+12C are studied within the collective clusterization approach using the dynamical cluster decay model (DCM). Except experimentally observed 6,7Li and 7,8,9Be fragments we have also studied 5He, 10,11B and 11,12C fragments. We have explored, firstly the effect of pairing coefficient and results shown the minute change in clustering effects due to its inclusion or non-inclusion, as the change in pairing energy coefficient at the given temperature of the reaction is not much significant. We see the enhancement in preformation probability of the fragments having the α-cluster structure in their complementary fragments. Secondly, the role of level density parameter has been investigated for both the spherical and deformed configurations. It is found that by changing level density parameter if there is enhancement in ℓ-summed up preformation probability of a particular fragment then there is decrease in the ℓ-summed up penetrability of the same fragment and vice versa, which accordingly affects the yields of the respective fragments. The DCM calculated cross sections follow the trend of experimental observations. The experimentally observed 6,7Li and 7,8,9Be fragments having complementary fragments 18F and 16,18O i.e. having α-cluster structure contributes more towards the yield as compared to fragments with absence of α-cluster.

Decay aspects of the compound nuclei formed via CF and ICF path in 12C[formula omitted]Cr reaction

The reaction dynamics of 12C+52Cr reaction induced via a cluster-structured projectile (12C) is examined theoretically using the dynamical cluster decay model (DCM) with respect to the recent experimental data available at wide span of center-of-mass energies (Ec.m.=41.84-71.20 MeV). In view of the cluster-structured projectile, a systematic analysis is carried out for both complete fusion (CF) and incomplete fusion (ICF) channel. The calculations are done by including the quadrupole (β2) deformations and optimum (θiopt.) orientation criteria of the decaying fragments. With an aim to have comprehensive analysis of the decay of compound nuclei formed via CF and ICF processes, the role of center-of-mass energy (Ec.m.) and angular momentum (ℓ) is explored in terms of various parameters of DCM such as fragmentation potential, preformation probability, penetrability and barrier modification. Further, the role of diffuseness parameter is also studied for 12C+52Cr reaction. For the given reaction, the contribution of light particles (LPs), and energetically favored intermediate mass fragments (IMFs) constitutes the decay cross sections. Therefore, the contribution of emitted LPs and IMFs is estimated for the decay of both compound nuclei formed via CF and ICF channels. Furthermore, the comparative analysis of different proximity potentials is also worked out for ICF. Finally, the effect of Ec.m. on the contribution of ICF cross sections is studied and compared with the experimental data.

Impact of noncoplanar degrees of freedom on quasifission contributions with the estimation of unobserved decay channels for the study of Pt*196 using the dynamical cluster-decay model

In Phys. Rev. C 98, 041603 (2018) it was demonstrated that the noncoplanar degrees of freedom (or azimuthal angle ${\mathrm{\ensuremath{\Phi}}}_{c}\ensuremath{\ne}{0}^{0}$), including higher-multipole deformations ${\ensuremath{\beta}}_{\ensuremath{\lambda}i}$ ($\ensuremath{\lambda}=2,3,4;\phantom{\rule{4pt}{0ex}}i=1,2$), and the compact orientations ${\ensuremath{\theta}}_{ci}$ are the most essential set of parameters in the dynamical cluster-decay model (DCM), in order to study heavy-ion reactions. In this work, we study the comparison between the coplanar ($\mathrm{\ensuremath{\Phi}}={0}^{\ensuremath{\circ}}$) and noncoplanar (${\mathrm{\ensuremath{\Phi}}}_{c}\ensuremath{\ne}{0}^{\ensuremath{\circ}}$) configurations, including higher multipole deformations, for $^{196}\mathrm{Pt}^{*}$ formed via the $^{132}\mathrm{Sn}+^{64}\mathrm{Ni}$ reaction. This reaction was earlier studied [M. K. Sharma et al., J. Phys. G: Nucl. Part. Phys. 38, 055104 (2011)] by one of our collaborators but only with $\mathrm{\ensuremath{\Phi}}={0}^{\ensuremath{\circ}}$, including quadrupole deformations, ${\ensuremath{\beta}}_{2i}$ alone having ``optimum'' orientations (${\ensuremath{\theta}}_{\mathrm{opt}.}$), with the result of noncompound nucleus [nCN, equivalently quasi-fission (qf)] contribution at higher energies. The only parameter of the DCM is the neck length $\mathrm{\ensuremath{\Delta}}R$, whose value for the nuclear proximity potential used here remains within its range of validity ($\ensuremath{\approx}2$ fm). The evaporation residues (ERs) and fission cross section (${\ensuremath{\sigma}}_{ff}$) are calculated in reference to available experimental data at near- and sub-barrier energies for $^{196}\mathrm{Pt}^{*}$. As a result of inclusion of ${\mathrm{\ensuremath{\Phi}}}_{c}\ensuremath{\ne}{0}^{\ensuremath{\circ}}$, the nCN contribution approaches zero at higher energies and corresponds to ${P}_{\mathrm{CN}}=1$, which is rather significant for the $\mathrm{\ensuremath{\Phi}}={0}^{\ensuremath{\circ}}$ configuration. Secondly, in this attempt we have tried to explore the evolution of the neck-length parameter ($\mathrm{\ensuremath{\Delta}}R$), which will help us to estimate the cross sections of unobserved decay channels.