Breakthrough in Nuclear Physics: First Precise Measurements of Tellurium-104 Decay

An international team of scientists has directly observed, for the first time, the exceptionally rapid alpha decay of tellurium-104 (¹⁰⁴Te) and carried out key measurements of its lifetime and decay energy. The results were published in the prestigious journal "Nature". The team, coordinated by Prof. Robert Grzywacz, included researchers from the University of Tennessee, Oak Ridge National Laboratory (ORNL), RIKEN, the University of Tokyo, the Faculty of Physics at the University of Warsaw, the National Centre for Nuclear Research, Universität zu Köln (Germany), Universidad Complutense de Madrid (Spain), Lawrence Livermore National Laboratory, and the Japan Atomic Energy Agency. Researchers from our Faculty involved in the project included Dr. hab. Agnieszka Korgul, University Professor, Dr. hab. Chiara Mazzocchi, University Professor, and Aleksandra Skruch, MSc.

Alpha decay is among the best-known forms of radioactivity. Yet for more than a century, physicists have sought to answer a fundamental question: how does an alpha particle — a system composed of two protons and two neutrons — form inside an atomic nucleus before it is emitted? Studies of the isotope ¹⁰⁴Te have provided new insight into this process.

The experiment was carried out at the Radioactive Isotope Beam Factory (RIBF) at the RIKEN research institute in Japan. Using four coupled cyclotrons, a beam of xenon-124 was accelerated and directed onto a beryllium target. This collision enabled scientists to produce extremely rare xenon-108 (¹⁰⁸Xe) nuclei, whose decay leads to the formation of ¹⁰⁴Te. Due to the very short lifetime of the tellurium isotope under study — on the order of just a few nanoseconds — the measurement posed a major experimental challenge. Thanks to advanced detection methods, it was possible for the first time to directly measure both the energy and the lifetime of the alpha decay of ¹⁰⁴Te.

The results show that ¹⁰⁴Te is the fastest ground-state nucleus currently known to physicists to decay by alpha-particle emission. Its measured half-life is approximately 7.2 nanoseconds. The data analysis also indicates an exceptionally high probability of so-called alpha-particle preformation, meaning the formation of the alpha particle inside the nucleus before the decay itself occurs. In the case of ¹⁰⁴Te, this effect proved stronger than in any atomic nucleus studied previously.

Prof. Robert Grzywacz of the University of Tennessee, who led the experimental team, emphasises that the measured probability of preformation was significantly higher than predicted by existing theoretical models based on earlier data. The results suggest that the tendency to form alpha particles increases markedly as atomic nuclei approach, in their structure, the “doubly magic” tin-100 (¹⁰⁰Sn). In such a system, the parent tellurium-104 nucleus behaves almost like a rigid tin-100 core with an already “prepared” alpha particle.

The team, coordinated by Prof. Robert Grzywacz, included researchers from the University of Tennessee, Oak Ridge National Laboratory (ORNL), RIKEN, the University of Tokyo, the Faculty of Physics at the University of Warsaw, the National Centre for Nuclear Research, Universität zu Köln in Germany, Universidad Complutense de Madrid in Spain, Lawrence Livermore National Laboratory, and the Japan Atomic Energy Agency. Researchers from our Faculty involved in the project included Dr. hab. Agnieszka Korgul, University Professor, Dr. hab. Chiara Mazzocchi, University Professor, and Aleksandra Skruch, MSc.

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