Efficient discrimination of transplutonium actinides by in vivo models

Transplutonium actinides are among the heaviest elements whose macroscale chemical properties can be experimentally tested.

Radiochemical Research with Transactinide Elements in Switzerland

Here, we present a review on a fundamental radiochemical research topic performed by Swiss scientists in national and international collaborations, utilizing large accelerator facilities at the Paul Scherrer Institute as well as abroad. The chemical investigation of the heaviest elements of the periodic table is a truly multidisciplinary effort, which allows scientists to venture into a variety of fields ranging from nuclear and radiochemistry to experimental and theoretical work in inorganic and physical chemistry all the way to nuclear and atomic physics. The structure and fundamental ordering scheme of all elements in the periodic table, as established more than 150 years ago, is at stake: The ever increasing addition of new elements at the heavy end of the periodic table together with a growing influence of relativistic effects, raises the question of how much periodicity applies in this region of the table. Research on the heaviest chemical elements requires access to large heavy-ion accelerator facilities as well as to rare actinide isotopes as target materials. Thus, this scientific area is inevitably embedded in joint international efforts. Its fundamental character ensures academic relevance and thereby substantially contributes to the future of nuclear sciences in Switzerland.

Astrophysical implications of neutron star inspiral and coalescence

The first inspiral of two neutron stars observed in gravitational waves was remarkably close, allowing the kind of simultaneous gravitational wave and electromagnetic observation that had not been expected for several years. Their merger, followed by a gamma-ray burst and a kilonova, was observed across the spectral bands of electromagnetic telescopes. These GW and electromagnetic observations have led to dramatic advances in understanding short gamma-ray bursts; determining the origin of the heaviest elements; and determining the maximum mass of neutron stars. From the imprint of tides on the gravitational waveforms and from observations of X-ray binaries, one can extract the radius and deformability of inspiraling neutron stars. Together, the radius, maximum mass, and causality constrain the neutron-star equation of state, and future constraints can come from observations of post-merger oscillations. We selectively review these results, filling in some of the physics with derivations and estimates.

Calculation of Q-value and half-life of alpha decay in super heavy elements using S-matrix theory

The half-life and the [Formula: see text]-value of alpha decay in several super heavy elements are calculated. The nuclear potential is computed using the double-folding method. Using the S-matrix theory, the alpha decay is treated as a scattering problem between alpha particle and the daughter nucleus. Nuclear potential was approximated by the parameterized Woods–Saxon potential. This idea has also been extended to predict the half-life and the [Formula: see text]-value of the heaviest elements of few other alpha chains.

Systematic Study of Quasifission in 48Ca-induced reactions

The production of superheavy elements through the fusion of two heavy nuclei is severely hindered by the quasifission process, which results in the fission of heavy systems before an equilibrated compound nucleus (CN) can be formed. The heaviest elements have been synthesised using 48Ca as the projectile nucleus. However, the use of 48Ca in the formation of new superheavy elements has been exhausted, thus a detailed understanding of the properties that made 48Ca so successful is required. Measurements of mass-angle distributions allow fission fragment mass distribution widths to be determined. The effect of the orientation of prolate deformed target nuclei is presented. Closed shells in the entrance channel are also shown to be more important than the stability of the formed CN in reducing the quasifission component, with reduced mass widths for reactions with the closed shell target nuclei 144Sm and 208Pb. Comparison to mass widths for 48Ti-induced reactions show a significant increase in the mass width compared to 48Ca-induced reactions, highlighting the difficulty faced in forming new superheavy elements using projectiles with higher atomic number than 48Ca.

Following Fission Products in Explosive Astrophysical Environments

The astrophysical process by which the heaviest elements are formed in the universe is known as the rapid neutron capture process, or r process, of nucleosynthesis. The r process is characterized by the neutron capture and β− decay of short-lived, neutron-rich atomic nuclei; in suitably extreme environments, nuclear fission can also play a major role in determining the ensuing nucleosynthesis. In this work, we present the application of our recently developed nucleosynthesis tracing framework to precisely quantify the impact that neutron-induced and β− -delayed fission processes have in r-process environments that produce fissioning nuclei.