Decay spectroscopy of heavy and superheavy nuclei

Abstract

After more than half a century since the first predictions of the so-called "island of stability of superheavy nuclei", exploring the limits of nuclear stability at highest atomic numbers is still one of the most prominent challenges in low-energy nuclear physics. These exotic nuclear species reveal their character and details of some of their properties through their induced or spontaneous disintegration. The achievements in the field of superheavy nuclei (SHN) research, which involves studying the production and decay of the heaviest nuclear species, have been reported in a number of review papers. In the introduction of this paper, references are provided to review papers, summarizing the many aspects of SHN research in other disciplines, like chemistry, atomic physics, and earlier work on nuclear structure, including in-beam spectroscopy, and superheavy element (SHE) synthesis. This review is an attempt to summarize the experimental progress that has been made in recent years by employing the versatile tool park of Decay Spectroscopy After Separation (DSAS) for the heaviest isotopes from Z=99 (einsteinium) to Z=118 (oganesson). DSAS, with its major instrumentation components heavy-ion accelerator, separator and decay detection, is the only way to access the heaviest nuclei up to oganesson. While in-beam γ-spectroscopy has reached 256Rf in terms of the highest atomic number Z and mass number A, SHE chemistry succeeded to sort flerovium (Z = 114) as the heaviest element into the periodic table. Laser spectroscopy and precise mass measurements are limited basically to the nobelium/fermium region, with high-precision Penning-trap mass-measurements being performed for 256Lr and 257Rf, and with the 257Db mass obtained, using a multi-reflection time-of-flight mass spectrometer (MRToF MS).