In the alpha decay of U-233, how many percent of the atoms go into the Th-229 isomer?

The alpha decay of U-233 is a well-established approach to obtain Th-229 atoms or ions in the isomeric state. In fact, it is the only method to date that has been shown to be capable of populating the isomer. Still, the probability of feeding the isomer has not been measured. A value of 2% is often found in literature, yet retracing how this number was obtained is difficult.

We used the available U-233 decay data from the NuDat database and, based on this data, calculated a probability of at least 1.98% for the isomer population. The NuDat data was generated by estimating or assuming a set of branching ratios for gamma and internal conversion transitions. The NuDat database can therefore be used as a reference for the 2%-value, but this value is based on estimated (not measured) branching ratios.

A short essay on the topic can be found here, questions and comments to the author are more than welcome!

Happy New Year 2017

We hope you all had a joyful holiday season. With 2017 just around the corner, nuClock wishes peace, luck, and success in 2017 to all of you: the partners, associates, fans & followers, and all your family and friends. Happy New Year!

“Physics World” 2016 Breakthrough of the Year

Towards the end of each year, the editors of the “Physics World” elect ten experiments or publications that they consider to be the most important scientific breakthroughs of the past year. Although an entirely subjective choice, this “Top-10” list has gained quite some visibility over the past years. To our great delight, the direct detection of the the Th-229 isomer by the LMU Munich group was ranked third among the ten breakthroughs of 2016! Congratulations to Lars, Bene, and Peter from Munich, and to their collaborators at GSI, Mainz, and elsewhere!

This year’s number-one went to be the discovery of gravitational waves by the LIGO collaboration. The magazine “Physics World” and the corresponding webpage are published by the British Institute of Physics (IOP), the full story can be found here.