Hours ago, the Large Hadron Collider was turned back on for preliminary test runs after being closed down for more than a year due to a major accident and subsequently discovered design problems. According to a recently posted New York Times article, tonight's events included sending protons around the large loop in one direction, with low-energy collisions soon to follow. However, actual operation at full capability for major physics discoveries is still a long ways away:
When the collider begins to do real physics next year, it will run at half its original design energy, with protons of 3.5 trillion electron volts. The energy will be increased gradually during the year, but it could be years, physicists say, before the machine reaches its full potential.
Thousands of the troublesome junctions will have to be rebuilt during a yearlong shutdown in 2011, and engineers have to figure out why several dozen of the superconducting magnets seem to have lost their ability to operate at high intensities.
From May-July 2007, I wrote a series of postings on the LHC and collider physics in general. I invite readers who might be interested in this background discussion to visit the earlier postings via the blog archives in the right-hand column.