New elements - approaching

Abstract

The search for new elements is part of the broader field of investigations of nuclei at the limits of stability. In two series of experiments at SHIP, six new elements (Z = 107-112) were synthesized via fusion reactions using 1n-deexcitation channels and lead or bismuth targets. The isotopes were unambiguously identified by means of α-α correlations. Alpha decay, not fission, is the dominant decay mode. The collected decay data establish a means of comparison with theoretical data. This aids in the selection of appropriate models that describe the properties of known nuclei. Predictions based on these models are useful in the preparation of the next generation of experiments. Cross sections decrease by two orders of magnitude from bohrium (Z = 107) to element 112, for which a cross section of 1 pb was measured. The development of intense beam currents and sensitive detection methods is essential for the production and identification of still heavier elements and new isotopes of already known elements, as well as the measurement of small α-, β-and fission-branching ratios. An equally sensitive set-up is needed for the measurement of excitation functions at low cross sections. Based on our results, it is likely that the production of isotopes of element 114 close to the island of spherical superheavy elements (SHEs) could be achieved by fusion reactions using 208 Pb targets. Systematic studies of the reaction cross sections indicate that the transfer of nucleons is an important process for the initiation of fusion. The data allow for the fixing of a narrow energy window for the production of SHEs using 1n-emission channels. The likelihood of broadening the energy window by investigation of radiative capture reactions, use of neutron deficient projectile isotopes and use of actinide targets is discussed.

Fission barriers and probabilities of spontaneous fission for elements with Z≥ 100

“…Considerable progress in the experimental synthesis of heaviest nuclei has been achieved recently by the Flerov Laboratory in Dubna [1,2,3,4,5,6,7,8,9,10,11] and was partially confirmed in the laboratories at GSI [12,13,14,15,16], LBNL [17] and RIKEN [18]. Nonetheless, the fundamental question of what is the largest possible atomic number of an atomic nucleus is still unanswered.…”

Shape evolution and collective dynamics of quasifission in the time-dependent Hartree-Fock approach

“…The creation of new elements is one of the most novel and challenging research areas of nuclear physics [1][2][3][4]. The search for a region of the nuclear chart that can sustain the so called superheavy elements (SHE) has led to intense experimental activity resulting in the discovery and confirmation of elements with atomic numbers as large as Z = 118 [5][6][7].…”

Time-dependent Hartree-Fock studies of the dynamical fusion threshold

“…The energy difference between fusion barrier and fission barrier is known as extra push energy. Recently, the experimental evidence [38][39][40] indicates that the extra push energy, needed in the formation of heavy and superheavy systems, is smaller than the prediction with macroscopic model [36].…”