Researchers from the Massachusetts Institute of Technology are developing an experiment to determine the rate at which stars produce oxygen, an essential reaction that has so far remained elusive to scientists.
Richard Milner, William Donnelly, and Ivica Friscic of the MIT Labratory of Nuclear Study co-authored a paper about the experiment that appeared Aug. 20 in the journal Physical Review C.
“The paper describes a new approach using advanced accelerator technology that has great potential to measure reaction rates in stars with higher precision,” he said. The rates “directly determine the abundance of oxygen in the universe.”
The rates also determine whether, after the supernova at the end of a massive star’s life, it collapses into a black hole or into a dense neutron star, researchers said.
When carbon and helium atoms collide inside stars, they fuse to form oxygen. Scientists have been trying to find the rate of this reaction for decades, in order to find out how fast stars are producing oxygen, MIT said in a statement.
This has proven to be very difficult. It is hard to recreate the energy levels found in stars in order to accurately find the reaction rate. So Milner and his team came up with a new approach.
Based off an idea from colleague Genya Tsentalovich from the late 1990s that never made it to the experimental phase, the physicists will be conducting the inverse of the reaction, Milner said. They intend to split oxygen nuclei back into carbon and helium.
The researchers plan to aim a particle accelerator’s high-intensity beam of electrons at a cold and dense cloud of oxygen atoms to break the atoms apart.
The researchers will track the reaction to determine its rate, then use that rate to determine the rate that the reaction in the opposite direction would occur.
The researchers are planning to conduct pilot experiments with an existing accelerator but ultimately a new, higher-powered version will be needed.
“Donnelly and I felt that [Tsentalovich’s idea] merited further study, and this was prompted by the construction of these new advanced accelerators,” Milner said.
One of these multimegawatt linear accelerators is under construction in Germany. The accelerator will probably not be ready until 2023, but MIT is collaborating with the team in Germany to design an experiment, Milner said.
Milner credits Friscic, a postdoctoral research associate who came to MIT from Croatia in 2016, with doing most of the legwork for the experiment. He also said that their research was funded in part by the Office of Nuclear Physcics at the US Department of Energy.