100 Years of Nuclear Isomers

In heavy and superheavy nuclei with Z > 100 several isomeric states are known to exist. Some of these isomers are rather long-lived and feature low excitation energies making their identification sometimes challenging. With the Penning-trap mass spectrometer SHIPTRAP at the GSI in Darmstadt, Germany, we can identify long-lived isomers and determine their excitation energy accurately. In recent...

When the liquid drop fission barrier vanishes in the fermium-rutherfordium region only the stabilization by quantum mechanics effects allows the existence of the observed heavier species. Those are in turn providing an ideal laboratory to study the strong nuclear interaction by in-beam methods as well as decay spectroscopy after separation [1].

Among the nuclear structure features to be...

A century after its discovery, isomerism has proven to be a very fertile tool for the study of nuclear structure, with an important impact on models development. As early as 1973, isomeric states were observed in the A~ 250 mass region in ²⁵⁰Fm and ²⁵⁴No by Ghiorso et al [1]. This region around Z = 100, N = 152 is characterized by prolate-deformed...

To date, the fission branch of only a handful of identified high-$K$ isomers has been measured or a lower limit inferred and, except in the cases of ${}^{250}$No [1-3] and ${}^{254}$Rf [4], all partial fission half-lives or their lower limits are reported to be shorter than the partial fission half-life of the corresponding ground state [5]. This is at odds with estimates of expected fission...