EPJ A Topical Collection: Heavy and Super-Heavy Nuclei and Elements: Production and Properties
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- Published on 12 May 2025
Guest Editors: Nicolas Alamanos, Maria José Garcia Borge, Sigurd Hofmann, Peter Möller, Andrey G. Popeko
Interest in the possible existence of elements (SuperHeavy Elements, SHE) at the next doubly-magic numbers beyond 20882Pb126, sufficiently stable to allow experimental studies of their properties, has been around since at least the 1950ies. In analogy with the magic neutron number 126 it was assumed that the next magic proton number would be Z = 126. However in the mid sixties it was realized that already available, calculated single-particle diagrams showed that Z = 114 would be a more plausible next magic proton number. This realization, the advent of the Strutinsky method, and improving experimental facilities led to many theoretical studies of SHE properties and to experimental efforts to form those. However in the next 15 years or so only a very few new elements (up to Z = 106) were discovered, none near the postulated island of stability. In a Nature article in 1979 Hermann reviewed the status and presented a somewhat bleak view of future prospects. Others had even remarked that the earlier Nobel symposium 27 in 1974 seemed to be the funeral services for SHE.
However, all this changed soon after new experimental facilities became available at GSI, Darmstadt in the late 1970ies. Three new elements with Z=107,108,109 were discovered there in rapid succession in 1981–1983 by “cold fusion” reactions, a type of reaction proposed by Oganessian in 1974. The stability of these new elements were not due to the next doubly magic shell, but Peter Armbruster pointed out to Peter Moller that a published 1981 mass table showed that large stabilizing microscopic effects and gaps in single-particle level diagrams at deformed nuclear shapes were present near Z = 108 and N = 162, and posed it could have something to do with the stability of the three new elements just discovered at GSI. This observation immediately led to a large number of theoretical studies of nuclei in the previously assumed “sea of instability” between the edge of the actinide region and the next doubly magic nucleus beyond Pb. There was now a decade-long lull in new-element discoveries, until the next upgrades at GSI. Then, again three new elements, namely Z = 110, 111, 112, were discovered in rapid succession in 1994–1996. The alpha-decay chain from element Z = 112 is particularly interesting because it shows a strong kink at Z = 108 and N = 162 and was the first confirmation of a local region of large microscopic effects at this location in the nuclear chart. In the next 15 years or so hot fusion reactions studied at Dubna led to the discoveries of elements Z = 114, 115, 116, 117, 118. Element Z = 113 was also discovered in this timeframe in cold-fusion experiments at Riken.
Now there has again been a more than ten-year lull in the discovery of new elements, so we may again ask, is it game over? Predictions of stability, based on models that have a very good record of predictive power indicate that the window to discoveries is only open to a very few additional elements before the age of new-element discovery is finally over after a run of several hundreds or even thousands of years.
This Topical Collection on Heavy and Super-Heavy Nuclei and Elements: Production and Properties has articles covering many aspects on the search for the elements terminating the periodic system, such as stability with respect to fission and alpha decay, evaporation residue cross sections, and experimental setups, techniques and considerations. Currently experimental searches for elements Z = 119 and Z = 120 are ongoing.
The articles included in the Topical Collection are available here and are freely accessible until 12 July 2025. For further information read the Editorial.
