Quantum Mechanical Fragmentation Research Articles

Exploring alpha emissions in neutron induced reactions via QMFT based dynamical cluster-decay approach

Abstract This study theoretically investigates alpha emission from compound nuclei formed in neutron-induced reactions, inspired by the experiments of Yu M. Gledenov et al. at Peking University, China. The research focuses on the decay dynamics of even-mass compound nuclei 144Nd* and 148Sm*, formed with neutron beam energies of 4 to 6 MeV. Employing the Dynamical Cluster-decay Model (DCM) based on Quantum Mechanical Fragmentation Theory (QMFT), high Q-value alpha emission channels 144Nd*→ 140Ce+α and 148Sm*→ 144Nd+α are explored. Cross-sections for alpha emissions are calculated by optimizing the neck-length parameter “∆R”, showing agreement with experimental data. Given the highly asymmetric incoming channel, the beam energy approximates the centre of mass energy (E beam≈E c.m. ). The study evaluates the impact of deformations, considering spherical and quadrupole-deformed configurations of the decaying fragments, and examines the alterations in potential energy surfaces. For deformed fragmentation, orientations are optimized for hot configurations. A comparative analysis of fragmentation structures, preformation profiles, and barrier characteristics is conducted between spherical and quadrupole-deformed fragmentation. The DCM’s collective clusterization approach treats all exit channels equally, emphasizing the formation of the preferred decay channel over competing channels such as fission. Observed changes in fragmentation profiles underscore the influence of nuclear parameters like angular momentum and deformations, providing insights into the dynamics of compound nucleus decay and the pivotal role of these parameters in shaping reaction outcomes.

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*).

Sequential decay analysis of $^{235}$U(n$^{th}$,f) reaction using fragmentation approach

Abstract Numerous experimental and theoretical observations conclude that the probability of the three fragment emission (ternary fission) or the binary fission increases when one proceeds towards the heavy mass region of nuclear periodic table. The collinear cluster tripartition (CCT) channel of $^{235}$U(n$^{th}$,f) reaction is studied and it was observed that the CCT may be a sequential process or a simultaneous emission phenomena. Till now, different approaches are introduced to study the CCT process as a simultaneous process or sequential process, but the decay dynamics of these modes is not fully explored. It will be of interest to identify the three fragments of the sequential process and to explore their related dynamics using some excitation energy dependent approach. Hence, in present work, an attempt is made to study the sequential decay mechanism of $^{235}$U(n$^{th}$,f) reaction using quantum mechanical fragmentation theory (QMFT). The decay mechanism is considered in two steps, where initially the nucleus splits into an asymmetric channel. In the second step, the heavy fragment obtained in the first step divides into two fragments. Stage I analysis is done by calculating the fragmentation potential and the preformation probability for the spherical and deformed choice of the decaying fragments. The most probable fragment combination of stage I are identified in view the dips in the fragmentation structure, and the corresponding maxima's of the preformation probability ($P_0$). The excitation energy of the decay channel is calculated using an iteration process. The obtained excitation energy of the identified heavy fragments is further used for the fragmentation analysis, and the subsequent binary fragments of the sequential process are obtained. The identified three fragments of the sequential process are in agreement with the experimental observation and are found nearby the neutron or proton shell closure. Finally, the kinetic energy of the observed fragments is calculated and the middle fragment of the CCT mechanism is identified.

Implication of compact configuration of hexadecapole deformed actinides in the synthesis of superheavy nuclei

The quadrupole (β2) deformed targets in the actinide region are found to be of great relevance in the production of superheavy nuclei (SHN), in the compact fusion mechanism. Recently, the application of “elongated” and “compact” configurations of pear-shape octupole (up to β3) deformed nuclei was found to play a significant role in the fusion-fission dynamics of heavy-ion induced reactions. In the present work, we intend to explore the relevance of higher-order deformed (up to β4) actinides and their compact configuration in the production cross-section as well as de-excitation of SHN (dynamics of 48Ca + 238U →286Cn∗ → A1 + A2 reaction). For the above analysis, we have calculated σER within the framework of dynamical cluster-decay model developed on the basis of quantum mechanical fragmentation theory, which has been extended with the inclusion of deformations up to β4 and corresponding compact optimum orientation. Besides, on the basis of this theory, the fragmentation structure of 286Cn∗ superheavy nucleus is examined in terms of fragmentation potential (Vη) and preformation probability (P0) as a function of fragment mass number.

Subsystem density‐functional theory (update)

AbstractThe past years since the publication of our review on subsystem density‐functional theory (sDFT) (WIREs Comput Mol Sci. 2014, 4:325–362) have witnessed a rapid development and diversification of quantum mechanical fragmentation and embedding approaches related to sDFT and frozen‐density embedding (FDE). In this follow‐up article, we provide an update addressing formal and algorithmic work on sDFT/FDE, novel approximations developed for treating the non‐additive kinetic energy in these DFT/DFT hybrid methods, new areas of application and extensions to properties previously not accessible, projection‐based techniques as an alternative to solely density‐based embedding, progress in wavefunction‐in‐DFT embedding, new fragmentation strategies in the context of DFT which are technically or conceptually similar to sDFT, and the blurring boundary between advanced DFT/MM and approximate DFT/DFT embedding methods.This article is categorized under: Electronic Structure Theory > Density Functional Theory

Quantifying the Nearly Random Microheterogeneity of Aqueous tert-Butyl Alcohol Solutions Using Vibrational Spectroscopy.

The microheterogeneous structure of aqueous tert-butyl alcohol (TBA) solutions is quantified by combining experimental, simulations, and theoretical results. Experimental Raman multivariate curve resolution (Raman-MCR) C-H frequency shift measurements are compared with predictions obtained using combined quantum mechanical and effective fragment potential (QM/EFP) calculations, as well as with molecular dynamics (MD), random mixture (RM), and finite lattice (FL) predictions. The results indicate that the microheterogeneous aggregation in aqueous TBA solutions is slightly less than that predicted by MD simulations performed using either CHARMM generalized force field (CGenFF) or optimized parameters for liquid simulations all atom (OPLS-AA) force fields but slightly more than that in a self-avoiding RM of TBA-like molecules. The results imply that the onset of microheterogeneity in aqueous solutions occurs when solute contact free energies are about an order of magnitude smaller than thermal fluctuations, thus suggesting a fundamental bound of relevance to biological self-assembly.

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.

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].

Quantum machine learning corrects classical forcefields: Stretching DNA base pairs in explicit solvent.

In order to improve the accuracy of molecular dynamics simulations, classical forcefields are supplemented with a kernel-based machine learning method trained on quantum-mechanical fragment energies. As an example application, a potential-energy surface is generalized for a small DNA duplex, taking into account explicit solvation and long-range electron exchange-correlation effects. A long-standing problem in molecular science is that experimental studies of the structural and thermodynamic behavior of DNA under tension are not well confirmed by simulation; study of the potential energy vs extension taking into account a novel correction shows that leading classical DNA models have excessive stiffness with respect to stretching. This discrepancy is found to be common across multiple forcefields. The quantum correction is in qualitative agreement with the experimental thermodynamics for larger DNA double helices, providing a candidate explanation for the general and long-standing discrepancy between single molecule stretching experiments and classical calculations of DNA stretching. The new dataset of quantum calculations should facilitate multiple types of nucleic acid simulation, and the associated Kernel Modified Molecular Dynamics method (KMMD) is applicable to biomolecular simulations in general. KMMD is made available as part of the AMBER22 simulation software.

Systematic study of probable target-projectile combinations for the synthesis of Z = 120 isotopes using the Skyrme energy density formalism

The synthesis of superheavy elements is an interesting field of research for both theoretical as well as experimental physicists. Till now superheavy element from Z=104 to 118 has been synthesized in various laboratories using cold and hot fusion reactions. Recent predictions of various theoretical models state that Z=120 and N=184 seems most probable doubly magic pair in the island of stability. Hence, we aim to the predict most probable target-projectile combinations of 300,302,304120 superheavy nuclei, so that relevant inputs may be imparted for future synthesis of superheavy nuclei. The target-projectile combinations are taken in reference to the minima's of the fragmentation potential calculated using the Quantum Mechanical Fragmentation Theory (QMFT). In addition, the target-projectile combinations from literature are also considered for which attempts were made for the synthesis of Z=120. The barrier height (VB) of the considered target-projectile combinations are calculated using the spherical and deformed choices of decay fragments. The percentage change in the barrier height ΔVB is explored for the hot and cold fusion approaches. The nuclear interaction potential is obtained within the Skyrme energy density formalism (SEDF) using the GSkI force parameters. For the feasible target-projectile (t-p) combinations, the capture cross-sections of these three isotopes 300,302,304120 are calculated using ℓ-summed Wong model and their comparative analysis is worked out. The probability of formation of compound nucleus (PCN) is determined using the energy dependent function. Among the thirty-six considered target-projectile combinations, the Ti-based reactions with Cf targets and also Cr-based reactions with Cm targets are identified as most suitable combinations for the synthesis of the superheavy element with Z=120. For 300120 isotope are 48Ti+252Cf, 50Ti+250Cf, 50Cr+250Cm, 52Cr+248Cm; whereas 50Ti+252Cf, 54Cr+248Cm, and 54Cr+250Cm form most probable target-projectile pair respectively, for 302120 and 304120 superheavy nuclei.

Systematic Analysis for Neck-Length and Q-Values on Cluster Decay from Ba Isotopes

The present study provides a detailed investigation of the neck-configuration and Q-values on the cluster decay of proton-rich even-even 124-128Ba isotopes using the relativistic mean-field (RMF) formalism with the NL3* parameter set. The densities of the interacting nuclei from the RMF approach are folded with the R3Y and M3Y interactions to obtain the nuclear potential via the double-folding technique. The preformed cluster model (PCM) based on the quantum mechanical fragmentation theory is employed for the calculation of the decay half-lives. The preformation probability P0 and the penetration probabilities are estimated by the phenomenological scaling factor of Blendowske & Walliser and the WKB approximation respectively. The present investigation reveals that the M3Y and R3Y are associated with different barrier characteristics which are significantly modified with a little variation in the neck-length parameter ΔR. From the Q-value analysis, we have demonstrated that α-decay may not be a favourable decay mode for proton-rich barium isotopes with A > 122.

Identification of Novel Natural Product Inhibitors against Matrix Metalloproteinase 9 Using Quantum Mechanical Fragment Molecular Orbital-Based Virtual Screening Methods.

Matrix metalloproteinases (MMPs) are calcium-dependent zinc-containing endopeptidases involved in multiple cellular processes. Among the MMP isoforms, MMP-9 regulates cancer invasion, rheumatoid arthritis, and osteoarthritis by degrading extracellular matrix proteins present in the tumor microenvironment and cartilage and promoting angiogenesis. Here, we identified two potent natural product inhibitors of the non-catalytic hemopexin domain of MMP-9 using a novel quantum mechanical fragment molecular orbital (FMO)-based virtual screening workflow. The workflow integrates qualitative pharmacophore modeling, quantitative binding affinity prediction, and a raw material search of natural product inhibitors with the BMDMS-NP library. In binding affinity prediction, we made a scoring function with the FMO method and applied the function to two protein targets (acetylcholinesterase and fibroblast growth factor 1 receptor) from DUD-E benchmark sets. In the two targets, the FMO method outperformed the Glide docking score and MM/PBSA methods. By applying this workflow to MMP-9, we proposed two potent natural product inhibitors (laetanine 9 and genkwanin 10) that interact with hotspot residues of the hemopexin domain of MMP-9. Laetanine 9 and genkwanin 10 bind to MMP-9 with a dissociation constant (KD) of 21.6 and 0.614 μM, respectively. Overall, we present laetanine 9 and genkwanin 10 for MMP-9 and demonstrate that the novel FMO-based workflow with a quantum mechanical approach is promising to discover potent natural product inhibitors of MMP-9, satisfying the pharmacophore model and good binding affinity.

Ternary fission analysis of Fm242,258 nuclei using equatorial and collinear cluster tripartition configurations

The quantum mechanical fragmentation theory--based three cluster model is employed to investigate the ground-state ternary fission of two Fm isotopes nuclei having atomic mass ${A}_{P}=242$ and 258. The mass asymmetry coordinate and the relative separation among the decaying fragments play a crucial role for the estimation of the fragmentation structure and related barrier penetration process. First, the choice of third fragment (${A}_{3}$) is fixed by minimizing the probable ${A}_{3}$ fragments having different proton neutron configurations. Further, the fission fragment combinations (${A}_{1}+{A}_{2}+{A}_{3}$) are identified for the fixed third fragments by selecting the channel of lower ternary fragmentation potential and higher relative fission yield. Two type of tripartition of radioactive nuclei are considered such as equatorial cluster tripartition (ECT) and collinear cluster tripartition (CCT). A comparative analysis of ternary fragmentation potential and relative fission yield within ECT and CCT geometrical arrangement is carried out for different choices of third fragment, i.e., ${A}_{3}=1$ to ${A}_{P}$/3. The choice of most probable fragments suggest that the proton and neutron magic shell closures play essential role in the ternary mass division. Finally, a relative analysis of binary and ternary fragmentation is worked out for better insight of dynamics involved.

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.

Binary and Ternary Fragmentation Analysis of 252Cf Nucleus using Different Nuclear Radii

Pioneering study reveals that a radioactive nucleus may split into two or three fragments and the phenomena are known as binary fission and ternary fission respectively. In order to understand the nuclear stability and related structure aspects, it is of huge interest to explore the fragmentation behavior of a radioactive nucleus in binary and ternary decay modes. In view of this, Binary and ternary fission analysis of 252Cf nucleus is carried out using quantum mechanical fragmentation theory (QMFT). The nuclear potential and Coulomb potential are estimated using different versions of radius vector. The fragmentation structure is found to be independent to the choice of fragment radius for binary as wellas ternary decay paths. The deformation effect is included up to quadrupole (β2) with optimum cold orientations and their influence is explored within binary splitting mode. Moreover, the most probable fission channels explore the role of magic shell effects in binary and ternary fission modes.

Effect of compact and elongated configurations on the spontaneous and induced fission of Fm isotopes

The spontaneous fission (SF) analysis of even mass $^{242\ensuremath{-}260}\mathrm{Fm}$ isotopes is carried out using a preformed cluster model based on quantum mechanical fragmentation theory. The deformation effects are included up to the quadrupole (${\ensuremath{\beta}}_{2}$) deformed nuclei with optimum orientations (${\ensuremath{\theta}}_{i}^{\mathrm{opt}.}$) leading to hot-compact (side-to-side) and cold-elongated (tip-to-tip) configurations. The spherical and hot-compact deformed configurations of decay fragments result in the symmetric fragment mass distributions for Fm isotopes; however, the symmetric peak gets sharper with an increase in the neutron ($N$) number of the parent nucleus. In the case of cold orientations, a transition from two-peaked (asymmetric fission) to three-peaked (multimodal fission) mass distribution is observed with an increase in the mass number of Fm. The SF half-lives (${T}_{1/2}^{\mathrm{SF}}$) are calculated using the neck-length parameter ($\mathrm{\ensuremath{\Delta}}R$) for $^{242\ensuremath{-}260}\mathrm{Fm}$ isotopes and compared with the experimental data. Besides this, the induced fission of Fm isotopes is studied within the dynamical cluster-decay model. The energy dependence of fission fragment mass distributions and the isotopic dependence is analyzed at energy range ${E}^{*}=5$--42 MeV. In addition, the role of temperature-dependent deformations in the fission dynamics is also explored.

Investigation of the cold valley paths for the synthesis of isotopes of Ubh in optimum orientations

Cold valley paths have been investigated for the synthesis of isotopes of superheavy element Unbihexium using quantum mechanical fragmentation theory, which suggests the fusion of fission fragments belonging to the cold valleys in the potential energy surfaces with at least one spherical closed shell nucleus as the reaction partner for the nuclear synthesis. For the suitability of the cold valley fission fragments for the synthesis of isotopes of Ubh, first the fragmentation potentials, preformation probabilities and fission barriers of the fission fragments of 314Ubh and 326Ubh compound systems in their ground states have been compared by keeping the fragments either in hot or cold optimum orientations. The comparison suggests 138Ba + 176Yb and 132Sn + 194Os reactions in hot optimum orientations for the synthesis of isotopes of Ubh due to their highest values of preformation probabilities, lowest values of the fragmentation potentials and relatively good values of the fission barriers. Also, the reactions 68Ni + 246Cf and 70Ni + 256Cf have been considered for the comparison with 138Ba + 176Yb and 132Sn + 194Os reactions due to their relatively smaller values of the Coulomb potential, higher mass-asymmetry and fission barrier, and shell closures next to 48Ca which has been used in most of the experiments for the synthesis of superheavy elements. Finally, the excitation functions for the neutron evaporation from the compound systems formed in these reactions, the probabilities of the formation and survival of the compound nuclei have been compared to suggest the suitable cold valley paths energies for the synthesis of the isotopes of Ubh.

Analysis of various competing binary and ternary decay processes of the Es253 nucleus

The ground state binary and ternary decays of the $^{253}\mathrm{Es}$ radioactive nucleus are investigated using the quantum mechanical fragmentation theory (QMFT) based cluster decay models. First, the relative fragmentation of $^{253}\mathrm{Es}$ is analyzed within the framework of the preformed cluster model (PCM). The PCM-calculated binary fragmentation structure is explored for two types of nuclear potential, i.e., Yukawa plus exponential and proximity potentials. The structure of the fragmentation potential and the location of potential minima are found to be independent of the choice of nuclear potential. It is observed from binary fragmentation structures that $\ensuremath{\alpha}$ $(^{4}\mathrm{He})$ decay, cluster $(^{46}\mathrm{Ar})$ emission, heavy particle $(^{82}\mathrm{Ge})$ radioactivity, and spontaneous fission fragmentation $(^{125}\mathrm{In})$ are the possible ground state decay modes of the $^{253}\mathrm{Es}$ nucleus. The competitive emergence of these decay channels is explored by studying the preformation probability ${P}_{0}$, penetrability $P$, and half-lives ${T}_{1/2}$. The calculated half-lives of $\ensuremath{\alpha}$ and spontaneous fission match nicely with the experimental measurements. Also, the half-lives are predicted for cluster and heavy particle radioactivity, for which experimental verification would be of further interest. Further, an effort is made to explore the possibility of ternary fission (particle accompanied fission) for the decay of the $^{253}\mathrm{Es}$ nucleus using the three-cluster model (TCM), where $^{4}\mathrm{He}$ is observed to be the third fragment along with two binary fission fragments. A comparison of relative yields of binary and ternary fission confirm that the probability of the binary fission decay mode is larger than that of ternary fission. Moreover, closed shell effects play a significant role in the symmetric and asymmetric fission of binary and ternary fission, respectively.

Decay of Hot and Rotating $${}^{\boldsymbol{88}}$$Mo$${}^{\boldsymbol{*}}$$ at Incident Energies of 300, 450, and 600 MeV

The reaction mechanism for the decay of the hot and rotating compound system $${}^{88}$$ Mo $${}^{*}$$ formed in $${}^{48}\textrm{Ti}+^{40}$$ Ca reaction and the time for the emission of outgoing fragments have been analyzed within the quantum-mechanical fragmentation theory based dynamical cluster-decay model, at three incident energies. The incident energy effects have been analyzed by comparing the decay modes at three incident energies, i.e. we have calculated and compared the (i) mass, charge, and angular momentum distribution of the cross section for light particles and intermediate mass fragments, (ii) angular momentum distribution of the reaction cross section, (iii) probability of compound nucleus and evaporation processes in the reaction, (iv) mass variation of the kinetic energy, velocity, penetration path length and time for the penetration process, and (v) average time for the process of emission of light particles, intermediate mass fragments and fission fragments. The reaction mechanism has been analyzed from the study of the variation of the reaction cross section with angular momentum.

Cluster radioactivity within the collective fragmentation approach using different mass tables and related deformations

The cluster decay of radioactive nuclei with mass $$^{221}\hbox {Fr}{\le }\hbox {A}{\le }^{252}\hbox {Cf}$$ decaying to lead and near-lead daughters are investigated considering four different sets of binding energies given by Moller et al. (At Data Nucl Data Tables 59:185, 1995) (MN1995), Moller et al. (At Data Nucl Data Tables 109:1, 2016) (MS2016) and Wang et al. (Phys Rev C 81:044322, 2010) (NW2010) with corresponding deformation parameters and experimentally measured data in 2017 (EX2017) considering deformations of the MN1995, MS2016 and NW2010 formalisms. The calculations are carried out using the preformed cluster-decay model based on the collective clusterization approach, which is inherited from the quantum mechanical fragmentation theory. With the incorporation of quadrupole deformations along with optimum cold orientations, the fragmentation potential changes for different choices of binding energy data and hence the preformation probability ($${P}_{0}$$) of the clusters get accordingly modified. The calculated half-lives of the cluster decays find reasonable agreement with the experimental data using the MS2016 formalism. Applying MS2016, the prediction of half-lives of some competing clusters (not measured so far) from known parents is also made in the lead and near-lead region, which could possibly provide new edges for cluster-decay measurements. Further, the role of axial deformations ($$\beta _{2}$$–$$\beta _{4}$$) from various formalisms along with cold elongated configurations of decay products is analyzed in view of cluster emission from the radioactive nuclei considered. The fragmentation profile calculated using MN1995, MS2016 and NW2010 gets significantly influenced when $$\beta _{2}$$-deformations are replaced with $$\beta _{2}$$–$$\beta _{4}$$ deformations. Nearly $$32\%$$ of the clusters are not observed in the decay path using theoretical binding energies and deformation parameters of MN1995, which reduces to $$16\%$$ for MS2016 and $$7\%$$ for NW2010.