High-temperature 205Tl decay clarifies 205Pb dating in early Solar SystemOPEN ACCESS 

Guy Leckenby, Ragandeep Singh Sidhu, Rui Jiu Chen, Riccardo Mancino, Balázs Szányi, Mei Bai, Umberto Battino, Klaus Blaum, Carsten Brandau, Sergio Cristallo, Timo Dickel, Iris Dillmann, Dmytro Dmytriiev, Thomas Faestermann, Oliver Forstner, Bernhard Franczak, Hans Geissel, Roman Gernhäuser, Jan Glorius, Chris Griffin, Alexandre Gumberidze, Emma Haettner, Pierre-Michel Hillenbrand, Amanda Karakas, Tejpreet Kaur, Wolfram Korten, Christophor Kozhuharov, Natalia Kuzminchuk, Karlheinz Langanke, Sergey Litvinov, Yuri A. Litvinov, Maria Lugaro, Gabriel Martínez-Pinedo, Esther Menz, Bradley Meyer, Tino Morgenroth, Thomas Neff, Chiara Nociforo, Nikolaos Petridis, Marco Pignatari, Ulrich Popp, Sivaji Purushothaman, René Reifarth, Shahab Sanjari, Christoph Scheidenberger, Uwe Spillmann, Markus Steck, Thomas Stöhlker, Yoshiki K. Tanaka, Martino Trassinelli, Sergiy Trotsenko, László Varga, Diego Vescovi, Meng Wang, Helmut Weick, Andrés Yagüe Lopéz, Takayuki Yamaguchi, Yuhu Zhang & Jianwei Zhao

Nature, Published: 13 November 2024

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“Radioactive nuclei with lifetimes on the order of millions of years can reveal the formation history of the Sun and active nucleosynthesis occurring at the time and place of its birth. Among such nuclei whose decay signatures are found in the oldest meteorites, 205Pb is a powerful example, as it is produced exclusively by slow neutron captures (the s process), with most being synthesized in asymptotic giant branch (AGB) stars. However, making accurate abundance predictions for 205Pb has so far been impossible because the weak decay rates of 205Pb and 205Tl are very uncertain at stellar temperatures. To constrain these decay rates, we measured for the first time the bound-state β− decay of fully ionized 205Tl81+, an exotic decay mode that only occurs in highly charged ions. The measured half-life is 4.7 times longer than the previous theoretical estimate and our 10% experimental uncertainty has eliminated the main nuclear-physics limitation. With new, experimentally backed decay rates, we used AGB stellar models to calculate 205Pb yields. Propagating those yields with basic galactic chemical evolution (GCE) and comparing with the 205Pb/204Pb ratio from meteorites, we determined the isolation time of solar material inside its parent molecular cloud. We find positive isolation times that are consistent with the other s-process short-lived radioactive nuclei found in the early Solar System. Our results reaffirm the site of the Sun’s birth as a long-lived, giant molecular cloud and support the use of the 205Pb–205Tl decay system as a chronometer in the early Solar System.”