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UM physicists part of international team for historic first

September 24, 2020 — 

UM researchers on an international team of physicists have made the first precise measurement of the weak force between particles in the universe, verifying a theory of the Standard Model of Particle Physics.

Using a device called the the Spallation Neutron Source at the U.S. Department of Energy’s Oak Ridge National Laboratory, the scientists were able to measure the weak force exerted between protons and neutrons by detecting the miniscule electrical signal produced when a neutron and a helium-3 nucleus combined and then decayed moving through a target. 

The result was published in the journal Physical Review Letters.

As described in the online news site Mirage News

The Standard Model describes the basic building blocks of matter in the universe and fundamental forces acting between them. Calculating and measuring the weak force between protons and neutrons is an extremely difficult task.

Their finding yielded the smallest uncertainty of any comparable weak force measurement in the nucleus of an atom to date, which establishes an important benchmark.

UM physicist Dr. Michael Gericke said:

When a neutron and a helium-3 nucleus combine, the reaction produces an excited, unstable helium-4 isotope, decaying to one proton and one triton (consisting of two neutrons and one proton), both of which produce a tiny but detectable electrical signal as they move through the helium gas in the target cell.”

Gericke led the group that built the combined helium-3 target and detector system designed to pick up the very small signals and led the subsequent analysis.

Read the Mirage News story here.

An analysis and explanation of the discovery is here.

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