Superheavy Isotopes Research Articles

Relativistic Mean-Field Study of Alpha Decay in Superheavy Isotopes with 100 ≤ Z ≤ 120

Relativistic Mean-Field Study of Alpha Decay in Superheavy Isotopes with 100 ≤ Z ≤ 120

An alpha decay study of superheavy nuclei within a Coulomb and proximity potential model including a Q-value dependent surface diffuseness parameter

Using the Coulomb and Proximity Potential Model (CPPM) and a Q-value dependent surface diffuseness parameter in the proximity potential, the alpha decay half-lives of 75 experimentally synthesized superheavy nuclei were determined. Comparisons are made between the obtained results and experimentally determined alpha decay half-lives, as well as the predictions of Yang et al.’s recent study [Nucl. Phys. A 1014 (2021) 122250], which is based on the Unified Fission Model (UFM) with a new preformation parameter. The lowest standard deviation of 0.621 is obtained for CPPM calculations with Q-value-dependent surface diffuseness parameter. The calculation is extended further to estimate the alpha decay half-lives [Formula: see text]119 and [Formula: see text]120 superheavy isotopes and compared with the predictions of UFM. Finally, the results of the calculations are compared to the predictions of the UDL formula [Phys. Rev. Lett. 103 (2009) 072501] and the modified Hutsukawa formula [Nucl. Part. Phys. Proc. 339 (2023) 92].

Ternary fission of various Z=120 isotopes with 3H, 4He and 8Be as light charge particle

The spontaneous cold ternary fission of various Z = 120 isotopes accompanied by light charge particles (LCP's)3H, 4He and 8Be in equatorial configuration is investigated using Unified ternary fission model (UTFM). The favourable ternary fission channel is predicted based on the computation of Q value, driving potential, barrier penetrability and relative yield of all potential ternary fragment configurations. For the parent isotopes 302,306,308,120 with LCP 3H, the maximum relative yield is for the combinations that have one fragment respectively as 131,132I and 139Ba, which are nearly magic. However, in the case of310120 with LCP 3H, the combination 145La+162Sm+3H exhibits the maximum relative yield. For the 4He accompanied fission of 302,306,308,310,120 isotopes, the fragmentation that include 139Cs, 140,144Ba and 131Te isotopes, which is in the vicinity of shell closure possess high relative yield. In the case of8Be accompanied ternary breakup of the parent isotopes 302,306,120, the maximum yield is due to the magic neutron shell and near-magic proton shell of 134Te. Whereas, for parent isotopes 308,310,120, it is due to the presence of respective doubly magic 132Sn and near doubly magic 131Sn as one fragment. Therefore, our findings emphasize the prominent role of both high Q value as well as existence of doubly and near doubly magic nuclei in the ternary fission of super heavy even-even isotopes 302,306–310,120, accompanied by light charge particles 3H, 4He and 8Be.

E-ΔE detection module of DGFRS-2 setup

Thе paper describes a new E-ΔE detection module which includes a position-sensitive double-sided strip detector (DSSD) and a low-pressure pentane-filled ΔE chamber for detection of Evaporation Residues (ERs) in complete fusion reactions. The goal is to synthesize superheavy isotopes at the new DC-280 (Dubna Cyclotron) cyclotron of the Joint Institute for Nuclear Research (JINR). With the 48Ca ion beam intensity of about 5–7 pμA (particle micro ampere) and the ΔE counter count rate of approximately 104 sec−1, we observe a decrease in the overall registration efficiency of the gas ΔE counter. The paper proposes a solution to this problem: introduction of an additional negatively biased electrode, which results in the stabilization of the ΔE detector operation.

Effects of deformation on the cluster and the [formula omitted]-decay half-lives for isotopes of the Trans-lead and the undetected superheavy nuclei

In the present investigation, based on the Wentzel–Kramers–Brillouin (WKB) approximation, and by considering deformation of the cluster and the daughter nuclei, the cluster radioactivity half-lives of 22 Trans-lead isotopes ranging from 221Fr to 242Cm are calculated. Also, the α-decay half-lives of even–even isotopes for the superheavy nuclei with Z in the range 104≤Z≤118 are computed. For the cluster radioactivity, a preformation factor, Pc depending on the atomic numbers of the cluster and the daughter nuclei is used according to the Santhosh and Jose (2021). The α preformation factor, Pα is evaluated based on the cluster-formation model (CFM). A universal decay law (UDL) proposed by Qi et al. (2009), was used to obtain the decay half-lives of the cluster and the α-decay for checking the credibility of our approach. The effects of the deformation of decay products on the half-lives of the cluster and the α-decay have also been investigated by comparing the obtained half-lives considering deformation with ones of the spherical nuclei and the results of the UDL as well as the available experimental data. Comparison indicates that our calculated cluster and α-decay half-lives considering deformation reproduce the experimental data more accurately than the UDL and the spherical nuclei. Furthermore, the cluster radioactivity half-lives of some isotopes that whose cluster radioactivity is energetically allowed but not observed preciously yet, are predicted. Also, the cluster and the α-decay half-lives and the branching ratios between them for some not yet discovered superheavy isotopes with Z=122 and Z=124 are obtained.

Study of isotopic yield and half-life of spontaneous fission for two (_ 104^266)Rf and (_104^268)Rf superheavy isotopes

Study of isotopic yield and half-life of spontaneous fission for two (_ 104^266)Rf and (_104^268)Rf superheavy isotopes

Theoretical predictions for α-decay chains and cluster radioactivity of superheavy nuclei with Z = 126

Theoretical predictions of [Formula: see text]-decay properties of several isotopes of the superheavy nucleus of [Formula: see text] [Formula: see text] and their consecutive [Formula: see text]-decay chains are presented. Based on the double-folding model, the [Formula: see text]–daughter interaction potential is constructed microscopically using a realistic M3Y–Paris nucleon–nucleon (NN) interaction. The [Formula: see text]-decay half-lives are computed for both spherical and deformed shapes of daughter nuclei within the density-dependent cluster model. The effect of deformation is found to decrease the [Formula: see text]-decay half-lives compared to spherical shapes. The calculated [Formula: see text]-decay half-lives are in satisfactory agreement with their counterparts using other theoretical methods. The prediction of the dominant decay mode for the isotopes [Formula: see text], which have not yet been experimentally synthesized, is presented through the competition between [Formula: see text]-decay and spontaneous fission. We have found that the isotopes [Formula: see text] survive fission and have relatively long half-lives which span the order [Formula: see text]–[Formula: see text]. Moreover, the correlation between the logarithm of the preformation probability deduced from the cluster formation model and the fragmentation potential for even–even [Formula: see text] isotopes is elucidated showing a negative linear relation. The feasibility of cluster emission from the superheavy isotope [Formula: see text] is investigated using different theoretical approaches. The predictions can provide useful guidance for future experimental researches.

Isotopic yields and spontaneous fission half-lives of 279Ds and 281Ds superheavy isotopes

In this paper, Isotopic yield and half-lives of cold spontaneous fission for [Formula: see text] and [Formula: see text] superheavy isotopes are studied. The interacting potential between fragments includes mean field proximity and Coulomb potentials. Fission [Formula: see text]-value, driving potential, [Formula: see text] and partial penetration probability of each possible individual fragmentation are calculated using [Formula: see text] approximation. According to the tunneling effect, the most favored pair of fragments is produced for the highest [Formula: see text]-value or the lowest driving potential. A few fragmentation with higher [Formula: see text]-value are selected for each atomic number Z. It is found that for [Formula: see text] isotope, the highest relative yield belongs to the [Formula: see text]Te + [Formula: see text]Ce fragmentation while for [Formula: see text], the combination [Formula: see text]Te + [Formula: see text]Ce has lowest driving potential and highest yield due to presence of fragments with magic or near magic proton and neutron numbers ([Formula: see text] and [Formula: see text]). By calculating yield of each fragmentation, its partial fission decay constant and then by summing over all decay constants for possible fragmentation, the fission decay constant for each superheavy isotope is obtained. Furthermore, half-life of each superheavy isotope is also estimated. Finally, the calculated half-lives using this method are compared with the experimental data. Good agreement achieved between our calculated half-lives and the experimental data.

Effect of nuclear potential on the formation cross section of superheavy isotopes of Og, Nh and Cn nuclei

Effect of nuclear potential on the formation cross section of superheavy isotopes of Og, Nh and Cn nuclei

Rate of decline of the production cross section of superheavy nuclei with Z=114–117 at high excitation energies

The production cross sections of superheavy nuclei with charge numbers $114-117$ are predicted in the $(5-9)n$-evaporation channels of the $^{48}$Ca-induced complete fusion reactions for future experiments. The estimates of synthesis capabilities are based on a uniform and consistent set of input nuclear data provided by the multidimensional macroscopic-microscopic approach. The contributions of various factors to the final production cross section are discussed. As shown, the specific interplay between survival and fusion probabilities unexpectedly leads to a relatively slow decline of the total cross-sections with increasing excitation energy. This effect is supported by a favorable arrangement of fission barriers protecting the compound nucleus against splitting concerning energetic thresholds for the emission of successive neutrons. In particular, the probabilities of the formation of superheavy nuclei in the $5n$-, $6n$-, and in some cases even in $7n$-evaporation channels are still promising. This may offer a new opportunity for the future synthesis of unknown neutron-deficient superheavy isotopes.

Self-consistent calculations of electron-capture decays in Z=118, 119, and 120 superheavy isotopes

Weak decays in superheavy nuclei with proton numbers Z=118−120 and neutron numbers N=175−184 are studied within a microscopic formalism based on deformed self-consistent Skyrme Hartree-Fock mean-field calculations with pairing correlations. The half-lives of β+ decay and electron capture are compared with α-decay half-lives obtained from phenomenological formulas. The sensitivity of the half-lives to the unknown Q-energies is studied by comparing the results obtained from different approaches for the masses. It is shown that α-decay is always dominant in this mass region. The competition between α and β+/EC decay modes is studied in seven α-decay chains starting at different isotopes of Z=118, 119, and 120.

Systematic study of alpha-decay of super-heavy isotopes withZ= 120–126

Alpha-decay half-lives of the even–even superheavy isotopes with proton numbers [Formula: see text] have been calculated within the cluster model. The alpha-daughter potential was constructed by employing the density-dependent double-folding model with a realistic nucleon–nucleon interaction whose exchange part has a finite range approximation. The half-lives were calculated using Wentzel–Kramers–Brillouin (WKB) approximation with the alpha preformation factor. The results have shown that the computed alpha-decay half-lives were in good agreement with their counterpart calculated by different semi-empirical approaches. The obtained results have also shown a negative linear relationship between the logarithm of the preformation factor and the fragmentation potential for the understudy isotopes. Also, the calculated results have shown that isotopes [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] had longer half-lives than their adjacent isotopes, which indicates that the corresponding neutron or proton numbers have a magical or semi-magical properties. Furthermore, we have studied the competition between alpha-decay and spontaneous fission to predict possible decay modes from the even–even isotopes [Formula: see text]. The results revealed that the isotopes [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] had alpha-decay as a predominant mode of decay and the nuclei [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] could not survive from the spontaneous fission. We hope that the theoretical prediction could be helpful for future investigation in this field.

Alpha decay and spontaneous fission in superheavy isotopes, Z = 124, using a density-dependent cluster model

Alpha decay (AD) and spontaneous fission (SF) half-lives of superheavy nuclei [Formula: see text] have been studied within the density-dependent cluster model. The alpha-nucleus potentials were calculated using the double-folding model with the realistic M3Y nucleon–nucleon interaction. To calculate nuclear half-lives, several semi-empirical formulas were used in addition to the Wentzel–Kramers–Brillouin (WKB) approximation. The calculated AD half-lives agree well with the values computed by the analytical formulas of Royer, the semi-empirical formula of Poenaru et al. and the Viola–Seaborg systematic. To identify the mode of decay of these nuclei, the SF half-lives were calculated using the semi-empirical formula given by Xu et al. The results show that among the isotopes studied, isotopes [Formula: see text] can be survived from the SF and have a half-life greater than [Formula: see text][Formula: see text](s). The study predicts [Formula: see text] chains from isotopes [Formula: see text], [Formula: see text] chains from isotopes [Formula: see text], [Formula: see text] chains from isotopes [Formula: see text] and an AD from [Formula: see text]. These isotopes have a half-life long enough to be synthesized in the laboratory. Also, in the decay chains of these isotopes, it is observed that the nuclei [Formula: see text] have higher half-lives than their neighbors. The neutron numbers corresponding to these isotopes are [Formula: see text] indicating the magical or semi-magical behavior of these numbers, which is in good agreement with the research results.

Possibilities of direct production of superheavy nuclei with Z=112–118 in different evaporation channels

The production cross sections of heaviest isotopes of superheavy nuclei with charge numbers 112–118 are predicted in the xn–, pxn–, and αxn–evaporation channels of the 48Ca-induced complete fusion reactions for future experiments. The estimates of synthesis capabilities are based on a uniform and consistent set of input nuclear data. Nuclear masses, deformations, shell corrections, fission barriers and decay energies are calculated within the macroscopic-microscopic approach for even-even, odd-Z and odd-N nuclei. For odd systems the blocking procedure is used. To find saddle points, the Imaginary Water Flow technique is used and non-axiallity is taken into account. As shown, our calculations, based on a new set of mass and barriers, agree very well with the experimentally known cross-sections, especially in the 3n–evaporation channel. The dependencies of these predictions on the mass/fission barriers tables, the ratio af/a, and fusion models are discussed. A way is shown to produce directly unknown superheavy isotopes in the 1n– or 2n–evaporation channels. The synthesis of new superheavy isotopes unattainable in reactions with emission of neutrons is proposed in the promising channels with emission of protons (σpxn≃10−200 fb) and alphas (σαxn≃50−500 fb).

Atomic Processes Accompanying Alpha Decay of Superheavy Nuclei

Processes involving the ionization of atomic shells and x-ray transitions in daughter nuclei and accompanying alpha decay of superheavy isotopes are considered. The probabilities for $$N$$ -shell ionization during the decay of isotopes entering into the tennessine ( $${}^{294}_{117}$$ Ts) and oganesson ( $${}^{294}_{118}$$ Og) alpha-decay chains are calculated. The Dirac–Fock method is used, and all multipole transitions and alpha-particle tunneling through the atomic Coulomb barrier are taken into account. The results of these calculations are analyzed and are compared with the $$K$$ -, $$L$$ -, and $$M$$ -shell ionization probabilities. The energies of the x-ray $$K_{\alpha_{1,2}}$$ lines are calculated for superheavy elements appearing as products of alpha decay in the $${}_{117}^{294}$$ Ts and $${}_{118}^{294}$$ Og chains. The Breit interaction and higher order electrodynamic corrections are taken into account. It is found that the energy of the $$K_{\alpha_{1}}$$ line of the meitnerium isotope $${}^{268}_{109}$$ Mt agrees within 0.01 keV with the results of earlier calculations. This indicates that the line observed at the GSI laboratory (Darmstadt) at an energy that is higher than the respective theoretical value by 3.2 keV does not admit an identification with the $$K_{\alpha_{1}}$$ line of $${}^{268}_{109}$$ Mt.

Search for the stable isotopes for Z = 119 and 121 superheavy elements using relativistic mean field model

An extensive study on the search of stable isotopes for Z = 119 and 121 superheavy nuclei is performed within relativistic mean field model with NL3 force for axially deformed nuclei. Our search is accomplished in the mass region, 289 ≤ A ≤ 339. The ground state properties such as binding energy, quadrupole deformation, root-mean square radius etc are calculated and compared with finite range droplet model (FRDM). Calculated results are found to be in good agreement with FRDM results. The stability of superheavy isotopes against all the elementary decay modes (α-decay, β-decay and spontaneous fission) are studied. The most stable isotopes are chosen by scrutinizing their various nuclear properties. For Z = 119, the stable isotopes are found to be 291,292119, 294-298119 and for Z = 121, only isotope 297121 found to be relatively more stable in their considered isotopic chain. The predicted stable isotopes in the superheavy region along their isotopic chain, are found near the proton drip line. Further, the single particle spectrum and deform density profile along different direction are shown for few predicted stable isotopes, to gather a sound knowledge on the their features.

A comparative study of α-decay and spontaneous fission for Z = 120 superheavy isotopes

In this study, we have investigated the [Formula: see text]-decay chains of even–even superheavy nuclei [Formula: see text] in the range of [Formula: see text]. The Hartree–Fock–Bogoliubov model is used to calculate the binding energy of these superheavy nuclei. We have included the so-called SkP skyrme function as an effective force and the quadruple deformations. The semi-empirical formulas are used in the reproducing [Formula: see text]-decay and spontaneous fission half-lives of these superheavy nuclei. By studying the decay chains of the Z = 120 isotopes and comparing them with the half-lives of spontaneous fission, it is predicted that the elements [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text],[Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are more stable than the neighboring isotopes in their parent [Formula: see text]-decay chain. The corresponding neutron and proton numbers represent magical behavior that is in agreement with the numbers predicted before. In this range, the predicted nuclei are found to have large enough half-lives to synthesize them in a laboratory.

A Study on the Emission of 1, 2 Proton Halo Nuclei from Parent with Z = 121–128 in the Superheavy Nuclei via Cluster Radioactivity

Probabilities for the emission of various one proton and two proton halo nuclei from parent superheavy (SH) isotopes with Z = 121–128 are studied with the Coulomb and proximity potential model (CPPM) as the interacting barrier. The half-lives and other characteristics for the emission of one proton halo nuclei, 8B, 11,12N, 17F, 23Al, 27,28P, and two proton halo nuclei, 9C, 17,18Ne, 20Mg, 29S from the SH parent isotopes are determined and plotted it as a function of neutron number of daughter nuclei. The shell closure effects of parent and daughter nuclei are evident from the plot of computed half-lives. The peaks in the plot of half-life show the shell closure of parent and dips in the half-life show the shell closure of daughter nuclei. In the SH region with Z = 121–128 and N = 147–194, we observed that neutron shell closure of parent occurs at N~184 and neutron shell closure of daughter nuclei at N~174–184. Moreover, the most probable proton halo nuclei emissions are also evident from the computed half-life values. We have also studied the Geiger-Nuttall plots of log10 (T1/2) vs. Q−1/2 and log10 (T1/2) vs. −ln(P) for all the selected proton halo nuclei emitting from the SH parent isotopes with Z = 121–128 and are found to be linear. From the linearity of these plots, we found that GN law is valid for the proton halo decay also.

Capture and fission analysis of various superheavy isotopes with ACN = 258–280

The capture and fission analysis of heavy ion induced fusion reactions leading to the formation of Z = 107–111 superheavy nuclei has been carried out. Attempts have been made to analyze the synthesis traits, such as excitation functions, formation probabilities, barrier characteristics etc. The ℓ-summed Wong model provides a decent description of available data on capture (σCap) and fusion-fission (σff) cross-sections and hence is exploited to make relevant predictions for future experiments. The capture and fusion-fission excitation functions are predicted for the least explored region of superheavy nuclei (SHN) i.e. Z = 107–111. The role of mass-asymmetry (η), Coulomb factor (ZPZT), deformation and orientations, Businari-Gallone mass-asymmetry (αBG), fission barrier (Bf) etc is duly explored. The present study concludes that the mass-asymmetric reactions involving 24Mg, 30Si, and 36S projectiles are preferred for the synthesis of unknown isotopes of Z = 107–111. Alternatively, the doubly magic 48Ca-projectile also provides a competing alternative to produce neutron-rich isotopes of the above-mentioned SHN.

Studies on the Existence of Various 1p, 2p Halo Isotopes via Cluster Decay of Nuclei in Superheavy Region

The 1p and 2p halo structures of various halo candidates are identified from the separation energy calculations and driving potential curves. 11N, 23Al, and 26,27,28P are belonging to the 1p halo structure with low S(p) than S(2p) but 27,28,29S shows 2p halo structure. The decay possibilities of the 1p halo nuclei 8B, 11,12N, 17F, 23Al, and 26,27,28P and 2p halo nuclei 9C, 17,18Ne, 20Mg, and 28,29S from the superheavy parent isotopes with Z = 103 to 114 are studied within the Coulomb and Proximity Potential Model by evaluating the decay half-lives. Plots connecting the half-life for the emission of proton halos with the neutron number of daughter nuclei give the evidence for the possibility for the existence of the selected halo nuclei. It is evident from the computed half-lives that the emission of 1p halo nuclei such as 8B, 12N, and 17F and 2p halo nucleus 18Ne from various superheavy isotopes is probable. The plot connecting computed half-lives versus neuron number of the daughter nuclei indicates the nuclear shell closure effect of parent and daughter nuclei at N=126, 132, and 138