SeaQuest begins taking data

Paul Reimer inspects part of the SeaQuest experiment, which began taking data last week. Photo: Reidar Hahn

On Thursday, Feb. 20, the SeaQuest experiment began taking physics data for the first time.

The experiment, managed by Argonne National Laboratory and conducted at Fermilab, aims to probe the internal structure of the proton and the strong force that binds its constituent parts, called quarks.

One of the questions SeaQuest will try to answer is how the effects of the strong force change when a proton is isolated from an atom, rather than situated inside it. It will also investigate a curious quark quantity turned up by an earlier Fermilab experiment, NuSea.

NuSea investigated the number of up antiquarks and down antiquarks swimming around in the sea of particles inside the proton. Contrary to the expectation that there would be equal numbers of both particles, it turned up evidence that there were more down antiquarks than up. It also showed that in a certain region of quark momentum, this was reversed.

SeaQuest aims to look further into this lopsided ratio. If it confirms NuSea’s findings, it may mean scientists will have to rewrite the textbooks on the interplay of the stuff that makes up protons.

“The fun can begin now that we’re taking data,” said Argonne physicist and SeaQuest spokesperson Paul Reimer. “We’ve been looking forward to running the experiment for a long time, so we’re eager to finally delve deep into the proton to better understand the universe that it constitutes.”

SeaQuest will continue taking physics data for two years. Then experiment members will dig into the data to mine the sea of particles that make up protons.

Fifteen institutions from around the world collaborate on SeaQuest.