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In this paper, we employ the density-dependent relativistic mean-field theory to study how the triaxiality and pairing interaction affect the inner fission barriers of actinide nuclei. It was found that the triaxiality reduced the inner barriers and improved agreement with experimental values for many actinides. However, about 1–2 MeV discrepancy to the experimental values still remained for some of the considered nuclei. Such a discrepancy could be made further smaller by increasing the BCS pairing strength parameter. In this work, we demonstrated that adjusting the paring strength was effective in reproducing the experimental inner fission barriers as well as "pairing rotational energy" and binding energy in a consistent manner for nuclei where the effect of the triaxiality on the inner barriers was significant. [ABSTRACT FROM AUTHOR]

In this paper, a stochastic approach based on two-dimensional dynamical model was used to simulate the fission process of the excited compound nucleus 1 7 8 W produced in 1 9 F + 1 5 9 Tb reaction. In the dynamical calculations, the elongation parameter of the nucleus was used as the first dimension and the projection of the total spin of the compound nucleus onto the symmetry axis, K , considered as the second dimension. The average pre-fission multiplicities of neutron, light charged particles and the total kinetic energy of the fission fragments were calculated for 1 7 8 W and the results of calculations compared with the experimental data over a wide range of excitation energy. In the dynamical calculations, dissipation was generated through the chaos weighted wall and window friction formula and the dissipation coefficient of K , γ k , was considered as a free parameter and its magnitude inferred by fitting measured data on the average pre-fission multiplicities of neutron and proton for the compound nucleus 1 7 8 W. It was shown that the results of calculations are in good agreement with the experimental data by using the dissipation coefficient of K in the range γ k = (0. 1 8 0 − 0. 2 1 0) (MeV zs) − 1 / 2 . It was also shown that the results of calculations with γ k = (0. 1 8 0 − 0. 2 1 0) (MeV zs) − 1 / 2 provide a better agreement with the experimental data than with a deformation-dependent dissipation coefficient. Furthermore, it was also shown that differences between the results of calculations for the total kinetic energy of the fission fragments calculated by using different values of dissipation coefficient of K are small. [ABSTRACT FROM AUTHOR]

The developed fission systematics depicts the projectile energy and the target mass dependence of fission cross-sections of heavy nuclei. The developed model is fitted using experimental fission cross-section data of 500–1665 MeV negative pion induced fission in 1 1 9 Sn, 1 9 7 Au and 2 0 9 Bi. The same systematics is further fitted using the cascade exciton model (CEM) calculations of the above-mentioned fission reactions. Parameterization of the model is performed by calculating its parameters and uncertainties in them. A comparison of the systematics predictions with experimental data and CEM calculations is made. Validation of the systematics using new target nuclei 1 5 2 Eu, 1 8 1 Ta, 1 9 8 Hg and 2 1 0 At (not included in the systematics development) over an extended range of pion energies, from 80 MeV to 2500 MeV, builds trust in it. The systematics is not valid for 2 3 2 Th and 2 3 8 U. The systematics is found to be valid for target nuclei from 1 1 9 Sn to 2 1 0 At and for incident negative pion energies from 80 MeV to 2500 MeV. Results are discussed in detail. Merits and demerits of the developed systematics have been concisely described. Valid conclusions and future perspectives are also given. [ABSTRACT FROM AUTHOR]

A data bank of negative and positive (80–1665 MeV) pion-induced experimental fission cross-sections of heavy nuclei from 119Sn to 238U is compiled using present results and published data from the literature. Corresponding calculations of fission cross-sections, using the cascade exciton model (CEM) are also included in the compilation. Fission cross-sections compiled in the data bank are examined critically. Mass and energy dependences of fission cross-sections are analyzed. Fission cross-sections of 238U targets are the highest and scale down approximately, for other targets studied, with fissility, (Z ± 1) 2 A . In the fissility expression, Z and A are atomic and mass numbers of the target while ± 1 refer to positive and negative pion projectiles. The presented data bank is of interest for students and researchers involved in the investigation of energetic light particle-induced fission of heavy nuclei. Nuclear fission of heavy nuclei has been classified into three regimes. Phenomenological discussion of the fission process is also given. [ABSTRACT FROM AUTHOR]

In this paper, we report recent results obtained in the development of digital pulse processing mathematics for prompt fission neutron (PFN) investigations using a twin ionization chamber (TIC) along with a fast neutron time-of-flight detector (ND). Due to some ambiguities in the literature concerning a pulse induction on TIC electrodes by fission fragment (FF) ionization, we first presented a detailed mathematical analysis of FF signal formation on the TIC anode. The analysis was done using the Shockley–Ramo theorem, which gives the relation between charged particle motion between TIC electrodes and the so-called weighting potential. The weighting potential was calculated by direct numerical solution of the Laplace equation (neglecting space charge) for the TIC geometry and ionization caused by FFs. Formulae for GI correction and digital pulse processing algorithms for PFN time-of-flight measurements and pulse shape analysis are presented and used in experiments for PFN investigations of two reactions, 2 3 5 U(n t h ,f) and 2 5 2 Cf(sf). Results of the measurements were compared to literature data to demonstrate the feasibility of the new developed techniques. These results were necessary for the development of a new PFN investigation facility consisting of a position sensitive fission fragment detector combined with 32 liquid scintillation neutron detectors. [ABSTRACT FROM AUTHOR]

A dynamical model is employed to determine some peculiar properties of the scission neutrons, i.e., those emitted at the rupture of the neck between the fragments during low energy nuclear fission. Thus, by a specially adapted procedure, we calculate the time-dependent decay rate. This, defines the character of the emission process: pulsed or exponentially. From the time dependence of the survival probability, we deduced the "half-life" of the scission neutron emission. The angular distribution of the scission neutrons with respect to the fission axis is calculated as well. This is obtained for sets of neutron wave functions defined by a given quantum number Ω (projection of the total angular momentum on the symmetry axis). A strong dependence on Ω was found, namely, wave functions with different Ω have different most probable emission angles: from emission along the fission axis (1/2) to emission perpendicular to the fission axis (9/2). This result leads to a new interpretation of the measured angular distribution of the prompt fission neutrons. Finally, an extension of the dynamical model (i.e., with a time-dependent potential also after scission) is presented. [ABSTRACT FROM AUTHOR]

In this work, we extend our earlier study [S. Chopra, Hemdeep, A. Kaur and R. K. Gupta, Phys. Rev. C93 (2016) 024603] of 1 2 C + 9 3 Nb → 1 0 5 Ag ∗ reaction at below- and near- to above-barrier energies for both coplanar ( Φ c = 0 ∘ ) and noncoplanar (Φ ≠ 0 ∘ ) degrees-of-freedom. Our main aim is to see the texture of variation of compound nucleus (CN) fusion probability P CN at all the experimentally available center-of-mass energies ( E c. m. ) in the range 41–69 MeV, using the dynamical cluster-decay model (DCM). In this study, we worked for both degrees-of-freedom, having compact configurations ( 𝜃 c i ) and including higher multipole deformations (quadrupole to hexadecapole, β 2 i − β 4 i ) of nuclei. In the work of above-mentioned reference, for 1 0 5 Ag ∗ (weakly fissioning nuclear system), we found a discrepancy in P CN , i.e., increasing function with increasing E c. m. , belongs to superheavy nuclei for the case of Φ c = 0 ∘ [see Fig. Fig.4 of [A. Kaur, S. Chopra and R. K. Gupta, Phys. Rev. C90 (2014) 024619], but this erroneous result moved to correct one after the inclusion of Φ ≠ 0 ∘ (decreasing with increasing E c. m. , weakly fissioning class), which encouraged us to check the trend of P CN at all available energies. Our evaluation framework shows the noncoplanar configuration, with higher multipole deformations β 2 i − β 4 i included, as the most probable configuration for studying the heavy-ion reactions [S. Chopra, Hemdeep, P. Kaushal and R. K. Gupta, Phys. Rev. C98 (2018) 041603(R)]. Second, our interest is to check the consistency of experimental data, where the experimentalists have given the data with the mixing of three different experiments for same reaction. In this study, we have found that our results are in good agreement and consistent with only the latest experimental data at five E c. m. 's (=41.097, 47.828, 54.205, 60.051 and 65.454 MeV), i.e., showing large (∼ 90%) noncompound nucleus contribution (or equivalently quasi-fission/Incomplete fusion) in the (total) fusion cross-section. [ABSTRACT FROM AUTHOR]

The validity of the Strutinsky prescriptions is tested within a state-dependent pairing interaction instead of a constant pairing strength. The amplitude of the pairing field is determined to reproduce the experimental values of the pairing gaps in the ground state of the parent 2 3 2 Th. The density-dependent delta interaction was used to compute the quantities related to the pairing corrections along a fission trajectory, such as Fermi energies, pairing gaps, and pairing effects. An enhancement of the pairing gaps during the penetration of the second barrier was evidenced in the case of the state-dependent pairing formalism. Moreover, the outer barrier calculated in the framework of the macroscopic–microscopic model is strongly suppressed. [ABSTRACT FROM AUTHOR]

It is important to study the different decay modes of superheavy nuclei such as spontaneous fission, ternary fission and cluster decay. We studied the spontaneous fission, ternary fission and cluster decay of predicted isotopes of superheavy nuclei Z=124 and compared with that of alpha decay. This enables us to study the competition between spontaneous fission, ternary fission, cluster decay and alpha decay in the superheavy nuclei Z=124. We have studied the half-lives and decay constants of different decay modes. We have also studied the branching ratio of alpha decay with respect to other decay modes. This study reveals that alpha decay is the most dominant decay mode for the superheavy nuclei 313–318124 and hence these nuclei can be detected through the alpha decay mode only. [ABSTRACT FROM AUTHOR]

The temperature-dependent preformed cluster model [PCM(T)] is employed to extend our recent work [Niyti, G. Sawhney, M. K. Sharma and R. K. Gupta, Phys. Rev. C91 (2015) 054606] on α-decay chains of various isotopes of Z=113–118 superheavy nuclei (SHN), to spontaneous fissioning nuclei 103266Lr, 104267Rf, 105266−268Db, 111281Rg, and 112282Cn occurring as end products of these α-decay chains. The behavior of fragment mass distribution and competitive emergence of the dominant decay mode, i.e., the α-emission versus spontaneous fission (SF), are studied for identifying the most probable heavy fission fragments, along with the estimation of SF half-life times T1/2SF and total kinetic energy (TKE) of the above noted isotopes of Z=103–112 nuclei decaying via the SF process. The mass distributions of chosen nuclei are clearly symmetric, independent of mass and temperature. The most preferred decay fragment is found to lie in the neighborhood of doubly magic shell closures of Z=50 and N=82, with largest preformation factor P0. In addition, a comparative study of the “hot compact” and “cold elongated” configurations of β2i-deformed and 𝜃iopt-oriented nuclei indicates significantly different behaviors of the two mass fragmentation yields, favoring “hot compact” configuration. [ABSTRACT FROM AUTHOR]

In our new approach, evaporation residue cross-sections for new superheavy nuclei with atomic numbers are estimated by calculation of vital characteristics of superheavy nuclei synthesis such as the fission barrier height, the compound nucleus formation probability and the survival probability of the residue nuclei. Our presented estimation is in good agreement with available experimental data. In addition, this new approach allowed us to predict the evaporation residue cross-sections for superheavy nuclei with and 120 via introducing synthesis box and compare our results with other models. It is shown that the fission barrier heights of two nuclei with and 120 are comparable with their corresponding neutron separation energies. It is suggested that for the synthesis of new superheavy nuclei, it is proper to use nearly double magic nuclei such as as our projectile, so that the fission barrier heights remain high. [ABSTRACT FROM AUTHOR]

We have studied the -decay half-life and spontaneous fission half-lives of isotopes of superheavy element in the range . A comparison of calculated alpha half-lives with the literature [D. N. Poenaru, R. A. Gherghescu and W. Greiner, Phys. Rev. C 83 (2011) 014601, D. N. Poenaru, R. A. Gherghescu and W. Greiner, Phys. Rev. C 85 (2012) 034615] and the analytical formulas of Royer [G. Royer, J. Phys. G; Nucl. Part. Phys. 26 (2000) 1149] shows good agreement with each other. To identify the mode of decay of these isotopes, the spontaneous-fission half-lives were also evaluated using the semiempirical relation given by [C. Xu, Z. Ren and Y. Guo, Phys. Rev. C 78 (2008) 044329]. A comparative study on the competition of alpha decay versus spontaneous fission of superheavy nuclei (SHN) reveals that around eight isotopes (122) survive fission and have alpha decay channel as the prominent mode of decay and hold the possibility to be synthesized in the laboratory. The alpha decay half-lives and spontaneous fission half-lives of SHN with , -306, with , -300, and with , -297 are also studied. The present study will be useful in the synthesis of superheavy elements by using the actinide based reactions with stable projectiles heavier than Ca. [ABSTRACT FROM AUTHOR]

We have studied the -decay properties of superheavy nuclei (SHN) in the range using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The calculated half-lives agree with the values computed using the Viola-Seaborg systematic, the universal curve of Poenaru et al. [ Phys. Rev. C 83 (2011) 014601; 85 (2012) 034615] and the analytical formulas of Royer [ J. Phys. G Nucl. Part. Phys. 26 (2000) 1149]. To identify the mode of decay of these isotopes, the spontaneous-fission half-lives were also evaluated using the semiempirical relation given by Xu et al. [ Phys. Rev. C 78 (2008) 044329]. The calculated half-lives help to predict the possible isotopes of this superheavy element . As we could observe chain consistently from the nuclei 124, we have predicted that these nuclei could not be synthesized and detected experimentally via decay as their decay half-lives are too small. The nuclei 124 were found to have long half-lives and hence could be sufficient to detect them if synthesized in a laboratory. [ABSTRACT FROM AUTHOR]

Fission barrier of the heavy nucleus Cf is analyzed in a multi-dimensional deformation space. This space includes two quadrupole () and three hexadecapole deformation () parameters. The analysis is performed within an unpaired macroscopic-microscopic approach. Special attention is given to the effects of the axial and non-axial hexadecapole deformation shapes. It is found that the inclusion of the nonaxial hexadecapole shapes does not change the fission barrier heights, so it should be sufficient to minimize the energy in only one degree of freedom in the hexadecapole space . The role of hexadecapole deformation parameters is also discussed on the Lublin-Strasbourg drop (LSD) macroscopic and the Strutinsky shell energies. [ABSTRACT FROM AUTHOR]

Reactor simulation is an important source of uncertainties for a reactor neutrino experiment. Therefore, how to evaluate the antineutrino flux uncertainty results from reactor simulation is an important question. In this study, a method of the antineutrino flux uncertainty result from reactor simulation was proposed by considering the correlation coefficient. In order to use this method in the Daya Bay antineutrino experiment, the open source code DRAGON was improved and used for obtaining the fission fraction and correlation coefficient. The average fission fraction between DRAGON and SCIENCE code was compared and the difference was less than 5% for all the four isotopes. The uncertainty of fission fraction was evaluated by comparing simulation atomic density of four main isotopes with Takahama-3 experiment measurement. After that, the uncertainty of the antineutrino flux results from reactor simulation was evaluated as 0.6% per core for Daya Bay antineutrino experiment. [ABSTRACT FROM AUTHOR]

Effects of the various neutron emission energy spectra, as well as the influence of the angular momentum of pre-scission neutrons on theoretical predictions of fission fragment angular anisotropies for several heavy-ion induced fission systems are considered. Although theoretical calculations of angular anisotropy are very sensitive to neutron emission correction, the effects of the different values of kinetic energy of emitted neutrons derived from the various neutron emission energy spectra before reaching to the saddle point on the prediction of fission fragment angular distribution by the model are not significant and can be neglected, since these effects on angular anisotropies of fission fragments for a wide range of fissility parameters and excitation energies of compound nuclei are not more than 10%. Furthermore, the theoretical prediction of fission fragment angular anisotropy is not sensitive to the angular momentum of emitted neutrons. [ABSTRACT FROM AUTHOR]

Nuclear fission has been modeled notoriously using two approaches method, macroscopic and microscopic. This work will propose another approach, where the nucleus is treated as a toy model. The aim is to see the usefulness of particle distribution in fission yield calculation. Inasmuch nucleus is a toy, then the Fission Toy Model (FTM) does not represent real process in nature completely. The fission event in FTM is represented by one random number. The number is assumed as width of distribution probability of nucleon position in compound nuclei when fission process is started. By adopting the nucleon density approximation, the Gaussian distribution is chosen as particle distribution. This distribution function generates random number that randomizes distance between particles and a central point. The scission process is started by smashing compound nucleus central point into two parts that are left central and right central points. The yield is determined from portion of nuclei distribution which is proportional with portion of mass numbers. By using modified FTM, characteristic of particle distribution in each fission event could be formed before fission process. These characteristics could be used to make prediction about real nucleons interaction in fission process. The results of FTM calculation give information that the value seems as energy. [ABSTRACT FROM AUTHOR]

A closed-form theoretical approach describing in a single picture both the evaporation component and the fast nonequilibrium component of the sequential fission of projectile-like fragments in a peripheral heavy-ion collision is derived and then applied to the dynamical fission observed in the + semiperipheral collision at 35AMeV. Information on the reaction mechanism is obtained such as the opposite polarization effects and the estimate of the 'formation-to-fast fission lifetimes' of the fissioning fragment. [ABSTRACT FROM AUTHOR]

We propose event by event velocity fluctuations of nuclear fission fragments as an additional interesting observable that gives access to the nuclear temperature in an independent way from spectral measurements and relates the diffusion and friction coefficients for the relative fragment coordinate in Kramers-like models (in which some aspects of fission can be understood as the diffusion of a collective variable through a potential barrier). We point out that neutron emission by the heavy fragments can be treated in effective theory if corrections to the velocity distribution are needed. [ABSTRACT FROM AUTHOR]

A combined dynamical model using concept of dinuclear systems (DNS) and one-dimensional (1D) Langevin equations was applied to investigate the effect of entrance channel on dynamics of heavy ions collision. The Si+Er, O+W and F+Ta reactions which formed the compound nucleus Pb have been considered to study this effect. We studied these reactions dynamically and calculated the ratio of evaporation residue cross-section to fusion cross-section as a tool for investigation of entrance channel effect. Results of combined model are compared with available experimental data and results of 1D Langevin equations. Obtained results based on combined model are in better agreement with experimental data in comparison with results of Langevin equations. We concluded for Si+Er and F+Ta reactions the results of combined model that support the quasi-fission process are different relative to Langevin dynamical approach, whereas for O+W system the two models give similar results. [ABSTRACT FROM AUTHOR]

The cluster decay process is studied in the WKB approximation based on the unified fission model. The cluster is considered to be emitted by tunneling through a potential barrier taken as the sum of the Coulomb potential, the centrifugal potential and the modified Woods-Saxon (MWS) nuclear potential. The results of our calculations are compared to those obtained by other theoretical models as well as experimental data. It is shown that the unified fission model with the MWS nuclear potential can be successfully used to evaluate the cluster decay half-lives of heavy nuclei. [ABSTRACT FROM AUTHOR]

The potential energy landscape for the synthesis is evaluated in the framework of the macroscopic-microscopic model. The fragmentation potential calculated in a configuration space characterized by five degrees of freedom associated to elongation, mass asymmetry, necking, and left/right deformations reveals the existence of several minima and some pronounced valleys. The valleys correspond mainly to the and quasifission channels, but also for some paths in the formation of the compound nuclear system. In this context, two different paths are obtained for the and entrance channels. The path leads to the formation of an isomeric minimum that decays by fission. The path evidences a larger probability for the formation of the compound nucleus. Therefore, the two distributions obtained for the associated quasifission processes are very different. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) dynamical model based on Langevin equations was applied to study the fission dynamics of the compound nuclei 228U produced in 19F + 209Bi reactions at intermediate excitation energies. The distance between the centers of masses of the future fission fragments was used as the first dimension and the projection of the total spin of the compound nucleus onto the symmetry axis, K, was considered as the second dimension in Langevin dynamical calculations. The magnitude of post-saddle friction strength was inferred by fitting measured data on the average pre-scission neutron multiplicity for 228U. It was shown that the results of calculations are in good agreement with the experimental data by using values of the post-saddle friction equal to 6–8 × 1021s-1. [ABSTRACT FROM AUTHOR]