Scientists are testing our fundamental understanding of the universe, and there is much to discover.
What are touch screen, radiation therapy and shrink wrap common? They were all made possible by particle physics research. The discovery of how the universe works on the smallest scale often leads to enormous advances in technology that we use every day.
The US Department of Energy (DOE), along with colleagues from 46 other institutions and seven countries, are conducting an experiment to keep our current understanding of the universe for scientific testing at the Arganne National Laboratory and the Fermi National Accelerator Laboratory.
The first result points to the existence of unseen particles or forces. This new physics can help explain long-standing scientific mysteries, and add new insights into a repository of information that can tap scientists into modeling our universe and developing new technologies.
The experiment, Muon G-2 (pronounced Mun G minus 2), is one that began at DOE’s Brookhaven National Laboratory in the ’90s, in which scientists measured a magnetic property of an elemental particle called muon.
The Brookhaven experiment yielded a result that differed from the value predicted by the standard model, with scientists describing the makeup and behavior of the universe as the best yet. The new experiment is a recreation of Brookhaven, designed to challenge or confirm the discrepancy with high accuracy.
The standard model very accurately predicts the muon’s G-factor – a value that tells scientists how this particle behaves in a magnetic field. This G-factor is assumed to be close to value two, and experiments measure their deviations from two, hence the name Muon G-2.
The experiment in Brookvane indicated that the G-2 differed from the theoretical prediction by a few parts per million. This minimal difference is indicated by the existence of unknown interactions between the muon and the magnetic field – which may involve new particles or forces.
The first result from the new experiment strongly agrees with Brookhaven, reinforcing the evidence that there is new physics to discover.
The combined results from Fermilab and Brookhaven show a difference from the standard model at the importance of 4.2 sigma (or standard deviation), slightly less than the 5 sigma that scientists need to claim a discovery, but still be able to claim new physics. Forcing evidence. The chance that the results are a statistical fluctuation is approximately 1 in 40,000.
Beyond standard models can help explain esoteric phenomena in particle physics, such as the nature of dark matter, a mysterious and widespread matter that physicists know, but has yet to be explored.
“This is an incredibly exciting result,” said Argono Ran Hong, a postdoctoral appointee who has worked on the MUN G-2 experiment for over four years. “These findings may have major implications for future particle physics experiments and may lead to a stronger understanding of how the universe works.”
The Argonone team of scientists contributed significantly to the success of the experiment. The original team, assembled and led by physicist Peter Winter, includes Argon’s Hong and Simon Corody as well as Suvarna Ramachandran and Joe Grange, who have left Argon.
“This team has an impressive and unique skill set with high expertise about hardware, operational planning and data analysis,” said Winter, who leads the MUON G-2 contribution from Argon. “They contributed significantly to the experiment, and we could not have achieved these results without their work.”
To obtain the real G-2 of the muon, Fermilab scientists produce a beam of MUN traveling in a circle through a large, hollow ring in the presence of a strong magnetic field. This area keeps Mun in the ring and rotates the direction of Moyen’s spin. The rotation, called scientific precedence, is similar to the rotation of the Earth’s axis, only very, very fast.
To calculate the G-2 to the desired accuracy, scientists need to measure two values with much greater certainty. One is the rate of spin precession of the muon as it detects the ring. The second is the strength of the magnetic field surrounding the muon, which affects its precedence. This is where Aragogna comes from.
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Although the muons travel through an impressive continuous magnetic field, changes in ambient temperature and effects from the hardware of the experiment cause slight changes throughout the ring. Even for these small changes in field strength, if not accounted for, the G-2 can significantly affect the accuracy of the calculation.
To correct for field variations, scientists continuously measure the area flowing using hundreds of probes mounted on ring walls. In addition, they send a trolley around the ring every three days so that the field strength can be measured, where the MUN beam actually passes.
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