CERN reports improved antiproton measurement18/01/17Science & Technology
The BASE collaboration at CERN has reported the most precise measurement ever made of the magnetic moment of the antiproton, allowing for a comparison between matter and antimatter.
The BASE measurement shows that the magnetic moments of the proton and antiproton are identical, apart from their opposite signs, within the experimental uncertainty of 0.8 parts per million. The result improves the precision of the previous best measurement by the ATRAP collaboration in 2013 by a factor of six.
BASE uses antiprotons from CERN’s unique antimatter factory, the Antiproton Decelerator (AD), and is designed specifically to perform precision measurements of the antimatter counterparts of normal matter particles.
To perform the experiments, the BASE collaboration cooled down antiprotons to the extremely low temperature of around 1° above absolute zero, and traps them using sophisticated electromagnetic containers so that they do not come into contact with matter and annihilate. From here, antiprotons are fed one-by-one to further traps where their behaviour under magnetic fields allows researchers to determine their intrinsic magnetic moment.
The new BASE measurement required a specially designed magnetic ‘bottle’ that is more than 1,000 times stronger than that used in electron/positron experiments.
Stefan Ulmer, spokesperson of the BASE collaboration, said: “This measurement is so far the culmination point of ten years of hard work by the BASE team.
“Together with other AD experiments, we are really making rapid progress in our understanding of antimatter.”
BASE now plans to measure the antiproton magnetic moment using a new trapping technique that should enable a precision at the level of a few parts per billion.
Lead author of the study, Hiroki Nagahama, added: “The implementation of this method is much more challenging than the method which was used here and will require several additional iteration steps.”