World's Most Precise Neutron Lifetime Measurement Has Been Made
A group of researchers from around the world have performed what they call the most precise measurement of the lifetime of a neutron in the world. The feat could shed light on questions scientists have concerning the early universe. The international team of physicists on the project was led by researchers from Indiana University Bloomington.
Researchers on the project are from ten different national labs and universities around the US and the world. Their new and highly precise measurement represents an improvement of two times compared to previous measurements. Researchers say the new measurement has a level of uncertainty of less than a tenth of a percent.
Researcher David Baxter says their work is a new "gold standard" for a measurement highly important to answering questions scientists have on topics like the relative abundances of elements created in the early universe. The purpose of the experiment was to measure how long a free neutron can live outside of atomic nuclei on average.
A neutron decays into a proton, and researchers have tried to measure that value with extreme precision to understand the precise lifetime of the neutron. The measurement can help scientists understand how the universe developed while allowing scientists to pinpoint errors in current models of the subatomic universe.
Scientists know there are errors in our current model of the subatomic universe, but they have been unable to pinpoint those errors. Researchers leverage neutrons for their experiments produced by the Los Alamos Neutron Science Center Ultracold Neutron source. The neutrons used in the experiment were lowered to near absolute zero inside a tub lined with around 4000 magnets. The team waited between 30 and 90 minutes before counting surviving neutrons inside the tub levitated by the magnetic force.
The test system allowed neutrons to be stored for more than 11 days, significantly longer than past designs. The long storage life allowed researchers to minimize any requirement for systematic corrections that could impact the lifetime measurements they were after.