A word from the CSO: The LHC experiments are going on-line

In the early discussions about experiments for a future high-energy proton collider the statement, "but we don’t know how to build detectors that can work in such an environment" was made more than once. On one hand I found this somewhat disconcerting, on the other hand it was encouraging in that it did not stop pioneers from starting to design experiments for the Large Hadron Collider. Initially, some ‘back of the envelope’ ideas were quite conservative, looking for very specific event signatures only, but today ATLAS and CMS are fully fledged ‘multi-purpose’ detectors featuring powerful tracking systems, high-resolution calorimetry and high-precision muon spectrometers. The dedicated experiments ALICE and LHCb and the smaller TOTEM and LHCf detectors are also state of the art.

I have actively followed the creation of the experiments as a member (and later the Chair) of the LHC Committee, as a director of NIKHEF, and for the past 5 years from here at CERN. Innovative R&D, prototyping, beam tests, detector production and integration have all achieved the necessary success after overcoming some unavoidable setbacks, some of which were technical (‘a challenge’) and some financial (‘a headache’).

The development of deep sub-micron electronics was a spectacular success and, with hindsight, a necessity. Very daring technologies were chosen for electromagnetic calorimetry: a success. The most powerful and complex superconducting magnet systems were built: a success. Trigger and data acquisition systems were designed anticipating advances in technology over the years of their development: they are now in place. These are only the highlights, and I hope the collaborations and ‘the machine’ will find the time to write a complete account of their ‘pre-history’. However, let me hasten to add that, although it was great to be part of all this from the beginning, the real heroes of this wonderful endeavour are the creative scientists and engineers who did all the work!

The control rooms have become busy places recently as the experiments are taking data! For the moment they are only registering particles sent to us from the sky, but they are providing very valuable tests indicating that each experiment is working as a system, including off-line data processing. An amazing ‘silent revolution’ has taken place during the past five years or so, which is the creation of the LHC Computing Grid. Not as a luxury, or a fancy IT development, but as a necessity without which LHC data analysis would in practice not be possible.

We are all very excited and once the experiments have recorded the first collisions we will also feel a little relieved. Very soon the LHC data will show us a first glimpse of Nature at an exceptionally high energy. After an absence of eight years CERN is back at the energy frontier!

Jos Engelen