New studies and a short review of heavy neutron-rich transfer products

We present new results on multi-nucleon transfer reactions in low-energy collisions of $$^{48}\hbox {Ca}+{}^{238}\hbox {U}$$ 48 Ca + 238 U measured at the velocity filter SHIP of GSI Helmholtz Centre, where we observed around 90 different nuclides from Tl to Am ($$Z=$$ Z = 81–95). We followed the idea to use uranium targets for the synthesis of neutron-rich MNT products, particularly in the region below lead, which was triggered by model calculations. The $$\gamma $$ γ , $$\alpha $$ α and spontaneous fission activities of the populated nuclides have been analyzed for their identification. The cross-sections of the observed isotopes for elements $$Z = $$ Z = 81–93 as a function of their mass number have been investigated. Excitation energy, total kinetic energy and the influence of nuclear shell effects on the production cross-sections of the observed transfer products have been studied. Also we present a compact review and comparative analysis of various multi-nucleon transfer and fragmentation reactions which are aimed at the synthesis of neutron-rich nuclides along the $$N=126$$ N = 126 shell closure in heavy nuclei.

APPEARANCE OF NUCLEAR SHELL EFFECTS AND INITIAL CHARGE (MASS) ASYMMETRY IN THE FORMATION OF PRODUCTS OF HEAVY ION COLLISIONS

The role of the entrance channel in the formation of the reaction products is discussed. The excitation functions of evaporation residues for the 50 Ti +249 Cf and 54 Cr +248 Cm reactions are compared.

NUCLEAR POINT-GROUP SYMMETRIES AND NEW IDEAS ABOUT NUCLEAR STABILITY: AN OVERVIEW

The nuclear mean-field theory and the group representation theory can be used to optimise the search for strong nuclear shell effects. The two theories allow to correlate the symmetry aspects with the presence of large gaps in the single-particle spectra, facilitate in this way the conditions of search for strong nucleonic- and nuclear-binding and thus for an increased nuclear stability. In this article we give a short overview of the related on-going research, focussing on the results of the TetraNuc Collaboration.

SYSTEMATIC STUDY OF SHELL EFFECT NEAR DRIP-LINES

The variation of nuclear shell effects with nucleon numbers is evaluated using the modified Bethe–Weizsäcker mass formula (BWM) and the measured atomic masses. The shell effects at magic neutron numbers N=8, 20, 28, 50, 82 and 126 and magic proton numbers Z=8, 20, 28, 50 and 82 are found to vary rapidly approaching the drip-lines. The shell effect due to one magic number increases on approaching another magic number. Thus, shell effects are not always negligible near the drip-lines.