From Scientific American:
After 14 years of construction and $8 billion, the world’s mightiest particle accelerator is about to get a taste of what it was built for. The Large Hadron Collider (LHC), nearing readiness outside Geneva, Switzerland, was designed to smash protons together at the highest energies ever achieved in hopes of unlocking new secrets of the universe. But to date, all that’s traveled through its circular beam pipe are ping-pong balls to test for obstructions. That’s all about to change. This weekend, CERN, the European Organization for Nuclear Research, plans to test a key component of the accelerator by injecting a low-intensity beam of protons clockwise into the LHC and letting it travel three kilometers (two miles) through the machine.
Assuming all goes as planned, the lab announced today that it will send the first beam around all 27 kilometers (17 miles) of pipe on September 10, the machine’s official start-up date. This weekend’s test will mark CERN’s first attempt to feed protons (or, simply, “beam”) into the LHC from a chain of smaller accelerators. These feeder accelerators cannot inject straight into the LHC because their pipes are enclosed in bulky magnets that steer the protons. Instead, protons enter the LHC ring at an angle. That means a magnet has to nudge the protons to enter the circular beam pipe on the tangent. This “kicker” magnet, which CERN has never had the chance to test until now, must switch on at precisely the right moment to nudge the near light-speed beam, and then switch off just as fast.
More here.