Fermilab is currently home to the most energetic particle accelerator in the world. The accelerator, called the Tevatron, accelerates protons and anti-protons around a large ring. The protons are then made to collide with the oncoming anti-protons. The resulting collisions are measured with one of two large detectors; D0 or CDF.
At CDF, I'm working mostly with the Silicon Group(sorry that links internal). One part of the CDF detector is comprised of several layers of silicon that form a cylindrical detector that has a diameter of something like 40cm and a length of a couple of meters or so. This detector is the closest detector to the beam-pipe and is used to accurately track particles that result from the collision of the proton/anti-proton beam at Fermilab.