The LHC is coming

We used to have a joke in the physics department. Whenever someone asked when the LHC would be ready to turn on, the answer was time-translation invariant: year after year, the response was always “In about seven years”.  In the past few years since I left academia I’ve lost track of developments, but I am delighted to hear that the facility is finally ramping up.  They plan to initiate calibration testing this fall, and if all goes well we can perhaps hope to see the first data collection toward the end of 2009.  This is great.

For those who don’t know, the LHC (the Large Hadron Collider) is a particle accelerator — the world’s largest and most powerful — at the CERN facility in Geneva.  CERN was most recently the site of the LEP accelerator, an electron-positron ring running on the Z⁰ resonance (about 91 GeV).  LEP made a number of great discoveries, including the W and Z bosons, and very cleverly measured the number of light neutrino types (3). (As an undergraduate I myself was able to analyze some of the LEP data, but my results are not among those accounted “great”.) LEP turned off in 2000, and in the intervening years the facility has been undergoing a major upgrade: the new collider will accelerate proton beams to collision energies of 14 TeV, making it the most powerful such machine yet constructed (and, quite possibly, ever to be constructed).  I visited CERN in 2003 and saw portions of the apparatus under construction, and it is an awe-inspiring project.

There are many hopes for this facility.  It is widely expected that it will discover the Higgs boson, or something very much like it (unless the Tevatron finds it first!). The Higgs is an essential component of the Standard Model of particle physics — the other particles acquire mass by interacting with it — but it has not yet been seen in the lab.  Many physicists also expect, or at least hope, that LHC will discover supersymmetry, a theoretical abstraction that proposes a close relationship between matter particles and forces, upon which many speculative theories have been erected.  Some will be looking for signs of extra spatial dimensions, or other more esoteric phenomena.  Everyone is hoping to find something unexpected, not least to justify the huge expense of building the thing.  If it should happen that they find nothing surprising — if, for instance, they find the Higgs and that’s all — it will probably be the death knell of the age of supercolliders.

I wish them well. I myself am no longer involved with this research, and I admit to a certain twinge of regret at having to watch this excitement from the outside. Still, it is exciting.

Here are a series of spectacular high-resolution photos of the facility.