University of Minnesota
School of Physics & Astronomy


Matter and anti-matter

Greg Pawloski
Alex Schumann

Greg Pawloski is an expert on antimatter. As such he works on one of the great unsolved mysteries of physics: what is the cause of the great asymmetry in matter and antimatter? Physicists have long theorized that there are antiparticles for every particle in the Universe and that these annihilate one another in pairs. Yet, if there were an equal number of anti-matter particles, there would be no matter in the Universe.

Pawloski looks for muon anti-neutrinos going to electron anti-neutrinos on the MINOS neutrino experiment. Pawloski says this is a new channel for MINOS. In the past, MINOS looked at the matter neutrino transitions, but not for the appearance of anti-matter neutrinos.

"A reason we are looking to see if matter and anti-matter behave differently," Pawloski says, "if they do behave differently than is predicted for this mode then that's totally unexpected and might indicate new physics." MINOS is winding down to make way for the new neutrino experiment NOvA, and will stop taking data in Spring, 2012. Pawloski expects his analysis will be completed within a year.
Pawloski also works on NOvA, looking for disappearance of anti-muon neutrinos and muon neutrinos. “Again, we’re looking for a difference between matter and anti-matter; a possible new interaction between neutrinos and matter. Is there something out there that we’re not expecting that will lead us forward in knowledge? We live in a universe that’s dominated by matter. "In our theories you always get matter and anti-matter together, but where is all the anti-matter?”
Pawloski’s job might sound a little like that of Mr. Scott the Engineer on Star Trek, but as a data analyst his work consists of computer software coding. Pawloski is running simulations of data they expect to see and then will use both the simulations and future data samples to develop new techniques for when he gets the real data from the detector that is being built at Ash River, MN. Pawloski says that most of this analysis will have to take place before NOvA begins taking real data with the detector at Ash River in 2013. "There’s work to be done before you actually look at the data and attach meaning to it."

The way NOvA will work is similar to MINOS. A beam will be fired from Fermilab, through a near detector, 100 meters underground. Particles will then travel through the Earth to a Far Detector in Northern Minnesota. The main difference is that the NOvA Far Detector will be on the surface rather than in the Soudan Underground mine so that they can measure the neutrinos as they come in at a different angle. Pawloski says that the far detector needs to much bigger than the near detector because, like pellets from a shotgun, the particles spread out as they get further from the source.