Eyes on the Sun: Naked thallium-205 ion decay reveals history over millions of years
The sun is an important engine that sustains life on earth, generating huge amounts of energy through the process of nuclear fusion. At the same time, it emits a continuous stream of neutrinos—particles that serve as messengers of its internal dynamics. Although modern neutrino detectors have revealed the sun’s current behavior, major questions remain about its stability over millions of years – a timeframe that spans human evolution and major climate changes.
Finding the answer to this question is the goal of the Lorante Experiment (LOREX), which requires a precise understanding of the solar neutrino cross section on thallium. This information has now been made available by an international collaboration of scientists, who used the unique facilities of the GSI/FAIR Experimental Storage Ring ESR in Darmstadt to obtain important measurements that will help understand the long-term stability of the Sun. The measurements have been published in a scientific journal Physical Review Letters.
LOREX is the only long-term geochemical solar neutrino experiment still actively underway. It was proposed in the 1980s to measure the average solar neutrino flux up to 4 million years, corresponding to the geological age of the lolandite ore.
Neutrinos produced in the Sun interact with thallium (Tl) atoms found in the mineral Rolandite (TlAsS2) and convert them into lead (Pb) atoms. isotope 205Lead is particularly interesting because it has a long half-life of 17 million years, making it essentially stable over the 4 million year timescale of chlormanganite ore. Since it is currently impossible to directly measure neutrino cross-sections 205Researchers Tl from GSI/FAIR in Darmstadt, Germany, have come up with an ingenious way to measure the relevant nuclear physics quantities needed to determine the neutrino cross section. They exploited the fact that this quantity of nuclear matrix elements also determines the fully ionized bound state beta decay rate. 205thallium81+ arrive 205lead81+.
Experimental Measurement of the Half-Life of Beta Decay in the Completely Ionized Bound State 205thallium81+ The realization of ions benefits from the unique features of the GSI/FAIR Experimental Storage Ring (ESR). ESR is currently the only facility that can perform such measurements. this 205thallium81+ The ions are produced via nuclear reactions in the GSI/FAIR Fragment Separator (FRS) and then stored long enough to observe and successfully measure their decay in the storage loop. “Decades of continuous advancement in accelerator technology have resulted in the generation of intense and pure accelerator 205thallium81+ “The ions beam and measure their decay with high precision,” said Professor Yuri A. Litvinov, spokesperson for the experiment and principal investigator of the European Research Council (ERC) Consolidator Grant ASTRUm.
“The team measured the half-life 205thallium81+ “Beta decays to 291 (+33/-27) days, which is a key measurement in determining the solar neutrino capture cross section,” explained Dr. Rui-Jiu Chen, a postdoctoral researcher involved in the project. 205The LOREX project has measured lead atoms in the mineral manganite, which will make it possible to gain insight into the evolutionary history of the Sun and its relationship to Earth’s climate over thousands of years.
“This landmark experiment highlights the power of nuclear astrophysics in answering fundamental questions about the universe,” said Professor Gabriel Martinez-Pinedo, who led the theoretical work that translated the measurements into neutrino cross sections. and Dr. Thomas Neff said.
Dr Ragandeep Singh Sidhu, first author of the publication, emphasizes its wider significance: “This experiment highlights how a single, albeit challenging, measurement can play a key role in solving major scientific questions related to the evolution of the sun. “
This publication is dedicated to the memory of late colleagues Fritz Bosch, Hans Geissel, Paul Kienle and Fritz Nolden, whose contributions were crucial to the success of the project.
2024-12-11 17:48:24