Synthesis of superheavy elements by cold fusion

Hofmann, S.

doi:10.1524/ract.2011.1854

Cited by 123 publications

(68 citation statements)

References 148 publications

(272 reference statements)

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“…These theoretical predictions led to two approaches to synthesize new elements [11,12,13]. Cold fusion reactions involving beams of Ca to Zn and targets of stable 208 Pb and 209 Bi where the excitation energy was so low only one neutron was evaporated were pioneered at GSI in Germany.…”

Section: Related Contentmentioning

confidence: 99%

The importance of closed shell structures in the synthesis of super heavy elements

Hamilton

Hofmann

Oganessian

2015

J. Phys.: Conf. Ser.

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Applications to nuclear properties of the microscopic-macroscopic model based on the semiclassical Wigner-Kirkwood method X Viñas, A Bhagwat, M Centelles et al. Abstract. The importance of shell closures and gaps in the single-particle energies for protons and neutrons on the stability of elements beyond Z = 100 will be described. Following the development of microscopic models with shell corrections, microscopic-macroscopic models predicted large gaps in the single-particle energy levels for protons and neutrons at Z = 102, 108 and N = 152, 162 for the same deformed shapes. Shell gaps for spherical shapes for N = 184 and Z = 114, 120 or 126 were also predicted to form an "Island of Stability" with very long half lives for fission and alpha decay. Cold fusion reactions involving beams of Ca to Zn and targets of stable By around 1965, eight new elements beyond U (Z = 92) up to Z = 100 had been discovered. Could one go further? Macroscopic models, like liquid drop models, at that time, predicted that nuclei beyond Z ≈ 100 could not be synthesized because beyond this Z the barrier against fission would go to zero and then nuclei would fission on a time scale T SF ≈ 10 -19 s. Then came the introduction of microscopic models with shell corrections [1]. Macroscopicmicroscopic models predicted large gaps in the single-particle energy levels for protons and neutrons for deformed shapes first for Z = 100, N = 152 [2] and then for Z = 102, N = 152 and Z = 108, N = 162 [3]. The reinforcement of the Z = 102, N = 152 and Z = 108, N = 162 level gaps at the same deformations provide the added stability to allow nuclei around these regions to have observable half lives (see Fig. 1). Calculations also predicted for N = 184 and Z = 114, 120 or 126 there were shell gaps for spherical shapes (for example, refs. 4-6). While all the calculations have predicted N = 184 is a spherical closed shell for neutrons, Z = 114, 120

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Section: Related Contentmentioning

confidence: 99%

The importance of closed shell structures in the synthesis of super heavy elements

Hamilton

Hofmann

Oganessian

2015

J. Phys.: Conf. Ser.

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“…Finally, for consistency, all results presented in this study were obtained with scaled pairing strengths of Eqs. (3) and (4). This includes all SHFB+LN excitation spectra shown in Fig.…”

Section: The Modelmentioning

confidence: 99%

“…Only very recently were electromagnetic transitions observed for the first time in the decay chain of 288 115 [1]. After decades of experimental studies, the heaviest SHE so far produced has proton number Z = 118 [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Rotational properties of nuclei aroundNo254investigated using a spectroscopic-quality Skyrme energy density functional

2014

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(2014). Rotational properties of nuclei around 254 No investigated using a spectroscopic-quality Skyrme energy density functional. Physical Review C, 89 (3) Background: Nuclei in the Z ≈ 100 mass region represent the heaviest systems where detailed spectroscopic information is experimentally available. Although microscopic-macroscopic and self-consistent models have achieved great success in describing the data in this mass region, a fully satisfying precise theoretical description is still missing. Purpose: By using fine-tuned parametrizations of the energy density functionals, the present work aims at an improved description of the single-particle properties and rotational bands in the nobelium region. Such locally optimized parametrizations may have better properties when extrapolating towards the superheavy region. Methods: Skyrme Hartree-Fock-Bogolyubov and Lipkin-Nogami methods were used to calculate the quasiparticle energies and rotational bands of nuclei in the nobelium region. Starting from the most recent Skyrme parametrization, UNEDF1, the spin-orbit coupling constants and pairing strengths have been tuned, so as to achieve a better agreement with the excitation spectra and odd-even mass differences in 251 Cf and 249 Bk. Results: The quasiparticle properties of 251 Cf and 249 Bk were very well reproduced. At the same time, crucial deformed neutron and proton shell gaps open up at N = 152 and Z = 100, respectively. Rotational bands in Fm, No, and Rf isotopes, where experimental data are available, were also fairly well described. To help future improvements towards a more precise description, small deficiencies of the approach were carefully identified. Conclusions: In the Z ≈ 100 mass region, larger spin-orbit strengths than those from global adjustments lead to improved agreement with data. Puzzling effects of particle-number restoration on the calculated moment of inertia, at odds with the experimental behavior, require further scrutiny.

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“…By assuming a simple Gaussian ansatz p(k) = e −a 2 k 2 , the two parameters G and a were adjusted to reproduce the density dependence of the gap at the Fermi surface in nuclear matter, calculated with a Gogny force. For the D1S parametrization [31] of the Gogny force the following values were determined: G = −728 MeV fm 3 and a = 0.644 fm [29]. When transformed from momentum to coordinate space, the interaction takes the form:…”

Section: Theoretical Frameworkmentioning

confidence: 99%

“…Enormous progress has been achieved in recent years in the synthesis and structure studies of superheavy elements [1][2][3][4][5][6]. These experiments present one of the most active fields at the forefront of nuclear physics research.…”

Section: Introductionmentioning

confidence: 99%

Structure of transactinide nuclei with relativistic energy density functionals

2013

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Structure of transactinide nuclei with relativistic energy density functionals Prassa, Vaia; Nikšic, T.; Vretenar, D.Prassa, V., Nikšic, T., & Vretenar, D. (2013 A microscopic theoretical framework based on relativistic energy density functionals (REDFs) is applied to studies of shape evolution, excitation spectra, and decay properties of transactinide nuclei. Axially symmetric and triaxial relativistic Hartree-Bogoliubov (RHB) calculations, based on the functional DD-PC1 and with a separable pairing interaction, are performed for the even-even isotopic chains between Fm and Fl. The occurrence of a deformed shell gap at neutron number N = 162 and its role on the stability of nuclei in the region around Z = 108 is investigated. A quadrupole collective Hamiltonian, with parameters determined by self-consistent constrained triaxial RHB calculations, is used to examine low-energy spectra of No, Rf, Sg, Hs, and Ds with neutron number in the interval 158 N 170. In particular, we analyze the isotopic dependence of several observables that characterize the transitions between axially symmetric rotors, γ -soft rotors, and spherical vibrators. An interesting example of a possible occurrence of shape-phase transitions and critical-point phenomena in this mass region is explored.

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Synthesis of superheavy elements by cold fusion

Cited by 123 publications

References 148 publications

The importance of closed shell structures in the synthesis of super heavy elements

The importance of closed shell structures in the synthesis of super heavy elements

Rotational properties of nuclei aroundNo254investigated using a spectroscopic-quality Skyrme energy density functional

Structure of transactinide nuclei with relativistic energy density functionals

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