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# Summary decay properties of the isotopes of odd-Z elements observed among the products of 48 Ca beam and 237 Np, 243 Am and 249 Bk target reactions. The numbers of the decay chains of the given isotopes, the products of corresponding xn-evaporation channels, observed in experiments with use of the DGFRS [26, 27, 34, 36, 66-70] (in red), chemical setup (in blue) [26, 71, 72] and TASCA (in grey) [73, 74] are shown. The average energies or energy intervals of α particles and half-lives are given for all α emitters observed in these experiments (yellow squares). The energy uncertainties given in brackets correspond to the data with the best energy resolution. For spontaneously fissioning nuclei marked by green squares the half-lives are listed.

Source publication

A review of the discovery and investigation of the 'island of stability' of super-heavy nuclei at the separator DGFRS (FLNR, JINR) in the fusion reactions of (48)Ca projectiles with target nuclei (238)U-(249)Cf is presented. The synthesis of the heaviest nuclei, their decay properties, and methods of identification are discussed. The role of shell...

## Contexts in source publication

**Context 1**

... first decay chain was observed at the DGFRS on 24 July, 2003. This involved two new elements at once, 288 115 and 284 113, followed by α decays of three new neutron-rich isotopes of the known ele- ments 280 Rg, 276 Mt and 272 Bh and SF of 268 Db (see figure 8). The electron-capture (EC) of 268 Db leading to presumably rapid SF of 268 Rf (T SF ~ 1 s [7]) could not be excluded as well. ...

**Context 2**

... spontaneously fissioning nuclei marked by green squares the half-lives are listed. figure 8). The decay properties of SHN will be discussed in the following section but here we emphasize that the decay properties of nuclei observed in the 243 Am + 48 Ca reaction evidently differ from those produced in the reactions with even-Z target nuclei. ...

**Context 3**

... cross-section values are not given in [73]. The summary decay properties of 287,288 115 are shown in figure 8. ...

**Context 4**

... this new long decay time just could confirm the assump- tion of [66]. In figure 8 we present result of a two-exponential fit [76] of all the available data for 276 Mt which suggests two half-lives. However, more statistics is still needed for definite conclusion. ...

**Context 5**

... of isotopes of the new element 117 was made similarly to that of the isotopes with Z = 115 produced in the 243 Am( 48 Ca, 2-4n) 287 294,293 117 reaction should have lower α-particle energies and respectively, longer lifetimes compared with the isotopes 288 115 and 287 115 produced in the reaction with 243 Am. Indeed, α-decay energies of all the descendant nuclei 289 figure 8). Furthermore, in spite of complex α-particle spectra of odd-Z nuclei, decay properties of 289 115 and 288 115 and descendant nuclei are different (compare T α values for nuclei in figure 8 and shape of α-particle spectra in figure 12 below, especially for isotopes of element 113). ...

**Context 6**

... α-decay energies of all the descendant nuclei 289 figure 8). Furthermore, in spite of complex α-particle spectra of odd-Z nuclei, decay properties of 289 115 and 288 115 and descendant nuclei are different (compare T α values for nuclei in figure 8 and shape of α-particle spectra in figure 12 below, especially for isotopes of element 113). At the same time, α- particle energies, decay times and decay modes of isotopes 289 115, 285 113, and 281 Rg observed in the reactions with 243 Am and 249 Bk agree. ...

**Context 7**

... the partial T α value for 268 Db exceeding that for 270 Db, suggested in [74], by more than two orders of magnitude (≥300 h) seems to be very unlikely. That is why we do not include results for 270 Db in figure 8 and below until finishing detailed analysis of the data ( [36] in [74]). ...

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## Citations

... The study on the superheavy elements (SHEs) is one of the most important topics in nuclear physics nowadays [1][2][3][4]. The cross section of fusion-evaporation reactions for producing superheavy nuclei (SHN) is extremely small, in the order of 10 −36 cm 2 and strongly dependent on the combination of two colliding nuclei and the incident energy. ...

The understanding of the fusion probability is of particular importance to reveal the mechanism of producing superheavy elements. We present a microscopic study of the compound nucleus formation by combining time-dependent density functional theory, coupled-channels approach, and dynamical diffusion models. The fusion probability and compound nucleus formation cross sections for cold-fusion reactions $^{48}$Ca+$^{208}$Pb, $^{50}$Ti+$^{208}$Pb, and $^{54}$Cr+$^{208}$Pb are investigated and it is found that the deduced capture barriers, capture cross sections for these reactions are consistent with experimental data. Above the capture barrier, our calculations reproduce the measured fusion probability reasonably well. Our studies demonstrate that the restrictions from the microscopic dynamic theory improve the predictive power of the coupled-channels and diffusion calculations.

... The production and spectroscopic study of superheavy nuclei (SHN) is currently one of the important topics in nuclear physics. The experiments on the synthesis of SHN with charge numbers Z = 112-118 [1][2][3][4][5][6][7][8][9][10][11] reveal the existence of island of stability for heaviest nuclei. Although the present experimental data do not allow us to fix the center and boarders of this island, they provide some clues for the theory to predict what the island of stability looks like: whether it is of a shape resembling a volcanic island of a well-centered distribution of stable SHN, or forming a coral reef with stable SHN distributed over an archipelago of binding energy peaks. ...

... For example, for the 48 Ca + 232 Th → 277 Ds +3n reaction, we predict a maximum cross section σ 3n ≈ 0.1 pb, which is smaller than the experimental production cross sections σ 4n = 16 +13 −7 pb (E * CN = 40.6 MeV [15]) [33] in the 48 Ca + 226 Ra → 270 Hs +4n reaction and σ 3n ≈ 3, 10, 3 pb in the reactions 48 Ca + 238 U → 283 Cn +3n, 48 Ca + 242,244 Pu → 287,289 Fl +3n, 48 Ca + 245,248 Cm → 290,293 Lv +3n, respectively [1][2][3]. The nucleus with Z = 110 seems to be the boundary nucleus between the mainland (where the last nucleus is Hs) and the island (archipelago) of stability of superheavy nuclei. ...

... The black triangles at the energy axis indicate the excitation energy E * CN of the CN at bombarding energy corresponding to the Coulomb barrier for the sphere-side orientation. The blue diamonds, green squares, red circles, and gray pentagons represent the experimental data[3] with error bars for 2n-, 3n-, 4n-, and 5n-evaporation channels, respectively. The symbols with the arrow indicate the upper limits of evaporation residue cross sections. ...

... An indication of enhanced stability of the recently synthesized SHN could be obtained through the investigation of their decay properties and the quantum shell effects [2,8,11]. Various nuclear structure models support the existence of an island of stability in the superheavy region around the expected neutron magic number = N 184 [12][13][14][15], however, they cannot agree on a specific proton number that will improve stability. The study of the 'island of stability' in the superheavy region is a topic of current nuclear physics research [10,11,13,[15][16][17][18][19][20][21][22]. ...

... Various nuclear structure models support the existence of an island of stability in the superheavy region around the expected neutron magic number = N 184 [12][13][14][15], however, they cannot agree on a specific proton number that will improve stability. The study of the 'island of stability' in the superheavy region is a topic of current nuclear physics research [10,11,13,[15][16][17][18][19][20][21][22]. High intensity ion beam systems and highly efficient detectors have been continuously developed, making it is feasible to synthesize several superheavy elements [14,15]. ...

... The study of the 'island of stability' in the superheavy region is a topic of current nuclear physics research [10,11,13,[15][16][17][18][19][20][21][22]. High intensity ion beam systems and highly efficient detectors have been continuously developed, making it is feasible to synthesize several superheavy elements [14,15]. ...

The empirical Royer formulas were readjusted with new set of coefficients using the latest experimental data and the recent evaluated α-decay half-lives over a wide range of 573 nuclei between 52 ≤ Z ≤ 118. The effects of the orbital angular momentum, isospin asymmetry, and parity have been examined in improving the adopted formulas. The modified formulas were tested for their accuracy by comparing with the recent experimental data and other theoretical calculations. The prediction of α-decay half-lives of several isotopes of the superheavy nuclei with Z = 120 − 126, which have not yet been experimentally synthesized, are presented and compared with other theoretical approaches. The behavior of log10 Tα in relation to the neutron number variation is explored for about 40 isotopes of each element. Based on the minima found in log10 Tα variation with neutron number, we found neutron stability at N = 184, 190, 196, 200, 202, 204, 210, 216, 218, 220 and 228. The behavior of log10 Tα with neutron variation for heavy and superheavy nuclei is almost the same as that found using more heavy and complicated calculations. The present method can be applied easily to study large number of nuclei.

... Experiments on complete fusion reactions with a 48 Ca beam and various actinide targets were successfully carried out at JINR (Dubna), GSI (Darmstadt), and LBNL (Berkeley) in order to synthesize superheavy nuclei (SHN) with the charge numbers Z = 112-118 [1][2][3][4][5][6][7][8][9][10]. The SHN with Z = 112 and 113 were also produced at GSI (Darmstadt) and RIKEN (Tokyo) in cold fusion reactions with target nuclei 208 Pb and 209 Bi [11,12]. ...

... The SHN with Z = 112 and 113 were also produced at GSI (Darmstadt) and RIKEN (Tokyo) in cold fusion reactions with target nuclei 208 Pb and 209 Bi [11,12]. The new Superheavy Elements Factory at JINR opens up new possibilities in SHN research [3,13]. So the study of the physical (the nuclear structure, the location of the shell closures, and the decay modes) and chemical properties of superheavy elements, as well as of the synthesis of new SHN, are of interest. ...

... Fast digital electronics allows resolving radioactive decays occurring on sub-µs timescales [57]. When TASCA became available for the search for new SHE, the elements with Z = 113-118 had already been claimed to be discovered at the GAs-filled Recoil Ion Separator (GARIS), operating at RIKEN, Wako-shi, Japan (Z = 113) [58], and at the Dubna Gas-Filled Recoil Separator (DGFRS) at the Flerov Laboratory for Nuclear Reactions (FLNR), Dubna (Russia) (Z = 114-118) [59]. Accordingly, the new element synthesis program at TASCA was dedicated to searches for elements Z = 119 and 120. ...

... The 244 Pu( 48 Ca,3-4n) 288,289 Fl and 243 Am( 48 Ca,3n) 288 Mc reactions have similar cross sections, ≈10 pb [59]. The second member of the 288 Mc decay chain is 284 Nh (T 1/2 ≈ 1 s), which is accessible for chemical studies after an α decay of the short-lived mother nuclide 288 Mc (T 1/2 ≈ 170 ms). ...

Superheavy element research has been a strong pillar of the research program at GSI Darmstadt since its foundation. Six new elements were discovered along with many new isotopes. Initial results on chemical properties of the heaviest elements were obtained that allowed for comparing their behavior with that of their lighter homologs and with theoretical predictions. Main achievements of the past five decades of superheavy element research at GSI are described along with an outlook into the future of superheavy element research in Darmstadt.

... For the heavy nuclei (A ≥ 120), the binding energy is significant in the process of cold fusion and hot fusion. In cold fusion, heavy targets such as lead or bismuth are bombarded with heavy ions of iron or nickel at energies above Coulomb barrier to form super heavy elements, while in hot fusion, the actinide targets are bombarded with calcium beams to form highly excited compound nucleus [11]. Currently, the hot fusion is the most successful technique in artificial synthesis of the super heavy nuclei. ...

A modified integrated nuclear model (MINM) for calculating the binding energies of finite nuclei is proposed. The model is an improvement of the integrated nuclear model (INM) that was formulated based on the theory of quantum chromodynamics. MINM is a simple model that depends on the proton and neutron numbers, and a variable stability coefficient factor denoted by λ. The variable λ rectifies the inequality in the neutron to proton ratio that results from the increase in the size of the nucleus. The results of the binding fraction obtained from MINM were compared with the existing experimental data obtained from atomic mass evaluation tables, AME2016. It was found that, the root mean square deviation for the binding fractions obtained from MINM is 0.2267 MeV with respect to the experimental data, while the root mean square deviation for the binding fraction obtained from INM is 1.5801 MeV. The root mean square deviation for MINM is very small. This supports the validity of the MINM and the consequent accuracy in the values of the binding fraction for different nuclei, especially in the region whereby A>220.

... Meitnerium is also predicted to be paramagnetic. Theoreticians have predicted the covalent radius of meitnerium to be 6 to (Oganessian and Utyonkov, 2015). ...

Nuclear geochemistry is the sub-field of isotope geochemistry dealing with radioactivity, nuclear processes, and transformations in the nuclei of atoms, such as nuclear transmutation and nuclear properties. The goal of this book is to clarify the basics and implementations of nuclear geochemistry. Topics covered include radioactive elements, nuclear reaction, radiometric dating, nuclear fuel cycle, nuclear pollution, and nuclear forensics.

... In hot fusion reactions, one uses a more asymmetric reaction typically involving a lighter projectile and an actinide target nucleus to increase the fusion probability but leading to a highly excited completely fused system with a reduced probability of surviving against fission. This approach has been used to synthesize elements with Z = 113-118 [15][16][17][18][19][20][21]. In the present work, we have studied the excitation functions (EFs) of 260 Sg*, formed in fusion reactions and 52 Cr + 208 Pb [22] based on Dynamical Cluster-decay Model (DCM) [23,24]. ...

... Both -decay and cluster models have been studied widely in recent years because of their effectiveness for understanding nuclei. That is, while on the one hand, -decay and cluster models can give insight about the parent nuclei's structure and lead us to a better understanding of the nucleus of the existing isotopes, on the other hand, they may play a critical role in understanding the accelerator production of the new super-heavy elements [11][12][13][14]. ...

... The -decay mechanism and realistic nuclear potentials have been studied widely, both theoretically and experimentally for a long time [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Sivasankaran et al. [17] studied Gamow theory of -decay, ranging between 62 ≤ Z ≤ 118 for even-even nuclei. ...

We have investigated the role of the deformation for the α decay half-lives with “cosh” nuclear potential. Wentzel–Kramers–Brillouin (WKB) approximation is used to calculate the half-lives together with Bohr–Sommerfeld quantization condition to put restrictions on the calculations. The nuclei are chosen between 106≤A≤273, including medium, heavy and super-heavy cases. The results are given for both spherical nuclear potential and deformed nuclear potential cases in order to make a suitable comparison. We have also compared the deviations of our results from the experimental data for the even–even and even–odd nuclei. We present that our results are in a very good agreement with the experimental data and also better than the previous works for some cases.

... The stability of many heavy and superheavy nuclei, which are produced in complete fusion reactions, is determined by either α decay or spontaneous fission (SF) [1][2][3][4]. The half-life of SF increases as one goes from an even-even to an even-odd nucleus, i.e., there is the hindrance for fission of odd-mass nuclei [5]. ...