In 2011 the Alpha Magnetic Spectrometer, or AMS, was launched into space. AMS, housed by the International Space Station and led by a Nobel Prize winning principle investigator, is commonly referred to as the most sophisticated particle physics experiment in space. The experiment was designed to study cosmic rays, a variety of high energy particles produced in space. In five years of operation, AMS has collected over 90 billion cosmic ray events, and a recently issued press release summarizes all new and recent results from the experiment.
One of the more exciting announcements is that AMS has observed a few candidate events for anti-helium particles. Such an observation would be a monumental discovery, and could help to elucidate why we live in an matter dominated universe. Scientists suspect that a physical process took place in the early universe that favored matter over anti-matter, but are unsure about exactly what happened, or even if a bunch of anti-matter particles are still hanging around. Ting explained that these candidate events require much more study, and an improved understanding of the detector before any official discovery could be announced.
Many other scientists were also keen to learn about a previously observed excess of positrons, the anti-matter particles for electrons. Early on in AMS data taking, Ting announced that the experiment observed more positrons at high energies than expected by theory. Ting suggested that these positrons could be produced by dark matter, while some other scientists believe the excess could be due to more traditional physics, like pulsars. Nevertheless it is clear that by 2024, the end of the International Space Station, AMS should be able to determine the source of these high energy particles.
These results, and many more, are being published in Physical Review Letters. The real message to be gleaned from the announcement is that physicists still have much more work to do. The current theoretical models of how cosmic rays are produced and propagate through the universe do not fully agree with the data observed in AMS. Theorists must continue to reevaluate the assumptions used when creating these models, and experimentalists must continue to analyze the incoming data. Everyone is looking forward to what mysteries AMS will unravel in the upcoming years.
Quantum Diaries – Latest News from Outer Space on Dark Matter
Symmetry Magazine – A syllabus in cosmic rays
Phys.org – Five years of studying cosmic rays with the Alpha Magnetic Spectrometer experiment
Managing Correspondent: Karri DiPetrillo