FAIR-GSI PhD Award 2025 for Dr. Guy Leckenby — Groundbreaking measurement of exotic decay unveils solar system formation
17.12.2025 |
Dr. Guy Leckenby has been awarded the FAIR-GSI PhD Award 2025 for his outstanding doctoral thesis on the study of bound-state beta decay with experiments conducted at the GSI/FAIR Experimental Storage Ring (ESR). His precision measurement of fully-ionized thallium-205 ions aided in resolving a decades-old puzzle about the origin of lead in our solar system and represents a flagship achievement for GSI/FAIR.
The award, sponsored by Pfeiffer Vacuum+Fab Solutions and valued at 1,000 euros, was presented by Professor Thomas Nilsson, Scientific Managing Director of GSI and FAIR, together with Daniel Sälzer, Managing Director of Pfeiffer Vacuum+Fab Solutions in Asslar, during a ceremonial colloquium at GSI/FAIR.
A 30-year quest completed
The measurement of bound-state beta decay in thallium-205 was among the major motivations for constructing the SIS-FRS-ESR facility complex at GSI and has been a flagship case for the NUSTAR/ILIMA Collaboration. Thallium-205 is stable as a neutral atom but decays when all bound electrons are removed — a phenomenon that can only be studied at heavy-ion storage rings like the ESR.
The experiment was successfully conducted in 2020 under extraordinary COVID-19 restrictions. Leckenby led the complex data analysis, employing advanced Monte Carlo and Bayesian techniques to determine a bound-state beta decay half-life of 291⁺³³₋₂₇ days. This experimental result was crucial for calculating accurate astrophysical decay rates for lead-205 and thallium-205 in stellar environments.
“It is a great honor to receive this award,” said Dr. Leckenby. “This measurement represents the successful completion of a 30-year endeavor that began with the very conception of GSI's storage ring program. Seeing this experiment come to fruition reflects not only decades of technical innovation but also the remarkable dedication of the entire GSI/FAIR community.”
Solving the lead mystery
Working with collaborators at GSI/FAIR and international stellar modeling groups, Leckenby applied the new decay rates to state-of-the-art asymptotic giant branch (AGB) star models. The results, published in Nature, revealed for the first time positive values for the isolation time of our solar system—the period between isolation from the interstellar medium and formation of the first solids. This provides crucial evidence that our Sun formed in a giant molecular cloud through standard galactic chemical evolution.
Outstanding Academic Excellence
Dr. Leckenby completed his doctoral studies at the University of British Columbia, Canada, under the supervision of Dr. Iris Dillmann (TRIUMF) and Prof. Reiner Kruecken (UBC), defending his thesis in December 2024 with excellent grades. Beyond the thallium measurement, he co-constructed and commissioned the PLEIADES detector for isotopic identification of heavy ions at the ESR, which is foreseen to be employed in future FAIR experiments.
His exceptional achievements have been recognized by multiple awards, including the SPARC PhD Prize 2025 and the GENCO Young Scientist Award 2025. His publication record includes first-author papers in Nature and Physical Review Letters, alongside 18 additional contributing-author publications.
“Guy Leckenby is an outstanding scientist and one of the young stars in nuclear astrophysics research,” said Professor Yury Litvinov, spokesperson of the experiment. “His contribution has been decisive, and his expertise in storage ring physics places him in a strategically important area for FAIR. Through his efforts, he continues the tradition and pioneering work of GSI's Professors Paul Kienle and Fritz Bosch, who fostered this experiment from its inception.”
Future at FAIR
Dr. Leckenby has accepted a postdoctoral position at LP2i Bordeaux (CNRS/IN2P3), France, where he will continue working with GSI/FAIR. He serves as spokesperson for an experiment to constrain the ²⁰⁵Pb(n,γ) cross section using surrogate reactions at the ESR as a part of the ERC-supported NECTAR project.
About the Award
The FAIR-GSI PhD Award is presented annually for outstanding dissertations supported by GSI/FAIR through strategic partnerships with universities in Darmstadt, Frankfurt, Gießen, Heidelberg, Jena, and Mainz. Over 300 doctoral students currently conduct GSI/FAIR-related research within the Helmholtz Graduate School for Hadron and Ion Research (HGS-HIRe).
GSI maintains a long-standing partnership with Pfeiffer Vacuum+Fab Solutions, a member of the global Busch Group and a world-leading provider of high and ultra-high vacuum technology solutions that have been successfully deployed in GSI facilities for decades. (CP)
