C. Scholey

Nuclear isomers in superheavy elements as stepping stones towards the island of stability

A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the ‘island of stability’; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons—the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.

α decay studies of the nuclides U 218 and U 219

Very neutron deficient uranium isotopes were produced in fusion evaporation reactions using

In-beam spectroscopy using the JYFL gas-filled magnetic recoil separator RITU

^{40}\mathrm{Ar}

Discovery of 157 W and 161 Os

ions on

Discovery of 157W and 161Os

^{182}\mathrm{W}

Coulomb shifts and shape changes in the mass 70 region

targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam and other reaction products. The activities were implanted into a position sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and the decays. Two

In-beam and decay spectroscopy of very neutron deficient iridium nuclei

\ensuremath{\alpha}

Shape coexistence at the proton drip-line: First identification of excited states in Pb180

-decaying states, with

Heavy Element Spectroscopy At JYFL

{E}_{\ensuremath{\alpha}}=(8612\ifmmode\pm\else\textpm\fi{}9)

Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151mLu

keV and