Of Beams and Bunches: The LHC record in perspective

The Large Hadron Collider reached a new milestone at 5.20 AM Central European Time, when it circulated two beams of protons – one clockwise and the other counter-clockwise – around the 27-kilometre-long ring. The beams each had energy of 3.5 tera-electronvolts (TeV).

This is a new record!

The previous record was set in November, when each beam reached an energy of 1.18 TeV.

Some more numbers to put this in perspective.

The LHC beams are considered “pilot” beams – meaning they are operating at very low intensities. When the LHC will be running at its peak, not only will each beam have an energy of 7 TeV, but each beam will be composed of 2,808 bunches of protons. When these bunches cross paths along four points of the LHC’s ring, they will collide and these collisions will produce about 100 billion particles per second.

The current 3.5 TeV beam at the LHC has only one bunch of protons per beam. What that means is that most of the beam is empty for now, as the physicists ensure that all their systems are in working order as they reach for higher energies and intensities.

According to Steve Myers, the Director for Accelerators and Technology at the LHC, they hope to reach 720 bunches per beam by the end of 2010.  They will do so by slowly upping the number of bunches in each beam: 4, 16, 43, 156… and so on. Such intensities are needed to start taking meaningful data for doing physics.

In my next post, I’ll discuss the technology behind “dumping” the beam. What happens when the beam cannot be controlled? How do you prevent it from smashing into the delicate electronics and frying them?