DZero’s data set

The lifetime performance of the Tevatron is tracked by the integrated luminosity, a measure of the number of particles delivered to the interaction region at DZero.

Carl Sagan, renowned astrophysicist, expounded on the wonders of outer space in his television series Cosmos, explaining the vastness of our own galaxy, which contains billions upon billions of stars, and how it is just one of tens of billions of galaxies in the observable universe. These numbers are mind-bogglingly large, but such is the nature of our universe and its impressive scale. This same scale applies to the data set that the Tevatron provided the DZero experiment over the past ten years, during collider Run II.

The performance of the Tevatron machine was remarkably impressive. Proton-antiproton collisions were produced around the clock. Taking into account the short time to reload each store of protons and antiprotons and technical stops to maintain the machine, collisions occurred for a total of over 41 thousand hours.

While running, bunches of protons and antiprotons passed through each other over 1.7 million times every second. Each of those beam crossings could have produced one or more collisions between protons and antiprotons, depending on how many antiprotons were created and stored in the Tevatron and how focused the particle beams were. In total, the Tevatron provided DZero with over 600 trillion proton-antiproton collisions, or 300 times more collisions than there are stars in our own galaxy!

Out of the over 200 trillion beam crossings that produced those collisions, DZero recorded over 10 billion events to use in our physics analyses. The triggering process that selects those events focuses on the most interesting ones. This process helps us pick out, for example, as many of the Higgs boson candidates as possible. If it exists, a standard model Higgs boson with a mass of 130 GeV would have been produced only 11 thousand times in the entirety of Run II, counting all of its production and decay modes. Since we are forced to reduce our data set to remove backgrounds when we are searching for the Higgs boson, efficiently running our data-taking operations and intelligently triggering events are both vital to the success of our physics program.

We will continue to produce measurements and perform searches using our data set for years to come!

—Mike Cooke

DZero recorded 90 percent of the luminosity delivered by the Tevatron over the course of Run II, thanks to the constant effort of the whole collaboration.