An international collaboration of scientists succeeded in the measurement of the bound-state beta decay of fully-ionised thallium (²⁰⁵Tl⁸¹⁺) ions at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The experiment, conducted at the Experimental Storage Ring (ESR) of GSI/FAIR and analysed in partnership with TRIUMF, Vancouver, revealed that the half-life of bare ²⁰⁵Tl⁸¹⁺ days, twice as long as theoretically expected. This measurement has profound effects on the production of radioactive lead (²⁰⁵Pb) in asymptotic giant branch (AGB) stars, which were simulated by collaborators at Konkoly Observatory, Budapest, and can be used to help determine how long the Sun took to form in the early Solar System. The results have been published in the journal Nature.

Please read more in the Nature article and our press release.
Read also the press release of GSI Darmstadt.

Almost 30 years after the first observation, the origin of the mysterious millisecond electron detachment signal of highly-excited C₂⁻ is explained by a new mechanism.

In order for an anion to neutralize, it has to get rid of its excess electron. It does so by coupling to internal states of its neutral counterpart. For a molecule this process is commonly believed to be (mostly) insensitive to its rotational excitation. However, this study shows that for C₂⁻ large rotation can “reshuffle” the positions of the electronic states both inside the negatively charged system and with respect to its neutral equivalent, C₂. As a result, the time scales in which the different decay processes occur change by many orders of magnitude.

Please read more in the Physical Review Letters article, the Physical Review A article and our press release.
Read also the synopsis in Physics Magazine.

What is the mass of a neutrino at rest? This is one of the big unanswered questions in physics. Neutrinos play a central role in nature. A team led by Klaus Blaum, Director at the Max Planck Institute for Nuclear Physics in Heidelberg, has now made an important contribution in "weighing" neutrinos as part of the international ECHo collaboration. Using a so-called Penning trap, it has measured the change in mass of a holmium-163 isotope with extreme precision when its nucleus captures an electron and turns into dysprosium-163. From this, it was able to determine the so-called Q value 50 times more accurately than before. Using a more precise Q-value, possible systematic errors in the determination of the neutrino mass can be revealed.

Please read more in the Nature Physics Article and our press release.

Further press releases:

• Phys.org
• ScienceAlert

Part of the science fiction genre is the famous protective shield that spaceships can raise. This is similar for atoms: The electron shell as an electromagnetic shield usually hinders the direct access to its nucleus. It also veils the nucleus’ precise structure, which, for example, makes some nuclei tiny magnets. A team in the group of Klaus Blaum, director at the Max Planck Institute for Nuclear Physics in Heidelberg, has now succeeded in precisely measuring the effect of this magnetic shielding in beryllium atoms. In this process, the nuclear magnetic moment of beryllium-9 could also be measured with 40 times better precision than previously known. This makes it the second most precise measurement of such a nuclear magnetic moment in the world, following the simplest atomic nucleus in hydrogen, the proton. Such precision measurements are not only relevant to fundamental physics. They also help to gain insight into certain applications of nuclear magnetic resonance which are applied in chemistry and for the highly accurate measurements of magnetic fields.

Please read more in the Nature Article and our press release (idw).