Around 10,000 scientists and engineers have been working over the last two decades on the largest experiment mankind has ever built. The Large Hadron-Collider (LHC) consists of an underground circular accelerator of 27 km in circumference, carrying two counter-rotating beams of protons accelerated to a very high energy before making them collide.

The study of the collisions, initially between protons and in later experiments also between lead ions, will provide a deeper understanding of the fundamental building bricks of the matter surrounding us. It will also bring important information about the conditions that existed shortly after the Big Bang, some 14 billions years ago. Scientists hope to extract substantial new knowledge about the smallest and shortest-lived particles, to confirm the existence of the Higgs boson as well as about incompletely understood phenomena of matter, space and time.

Important contribution from Switzerland

The Swiss research community has delivered important contributions for the LHC project. Involved in this extensive work for the gigantic detectors ATLAS, CMS and LHCb, are the ETH of Zurich and Lausanne, the Paul Scherrer Institute, as well as the Universities of Zurich, Bern, Geneva and Basel.

On Wednesday, 10 September, will be announced the starting signal for this ambitious project. The first proton beam should circulate in the LHC. The scientific community, and with it an interested public, impatiently waits for this historically significant moment.

The CMS detector – an extremely powerful microscope

A detector at an accelerator can be compared to an extremely powerful microscope that captures and analyzes the data coming from the signals left by particles resulting from the collisions.

CMS is designed to measure the energy and momentum of photons, electrons, muons and other particles with high precision, resulting in an excellent mass resolution for particles decaying into these final states. It consists of a powerful inner tracking system based on silicon technology (microstrip and pixel), a high precision crystal electromagnetic calorimeter (scintillating lead tungstate crystals) followed by a sampling hadronic calorimeter made from plastic scintillator tiles inserted between brass absorber plates, and a high magnetic field superconducting solenoid coupled with a multi-layer muon system.

CMS key features

• Has the largest superconducting solenoid ever built
• Contains the largest silicon detector (205 m² of sensors)
• Is the heaviest physics instrument ever built
• Has a magnetic field 100,000 times more powerful than the Earth’s field
• Results from a world wide collaboration between 2500 scientists from 184 institutions in 38 countries,
• Has the largest set of scintillating crystals ever built for a single experiment
• Weight 12,500 tons, diameter 15 meters, length 21.6 meters
• Magnetic field 4 Tesla

Switzerland is one of 38 countries participating in CMS with 3 research institutions in the CMS collaboration, and has supported 16% of the total costs of building the detector.

ETH Zurich, the Paul Scherrer Institute, the Universities Zurich and Basel (the last until 2004) actively contribute to the building, commissioning and operating parts of CMS as full members of the collaboration. The Swiss institutes were responsible or heavily involved in a number of advanced technological developments, including the pixel detector, the lead tungstate crystals, their avalanche photo-diode photo-detectors and the superconducting cable for the magnet coil. In addition, ETH-Zurich also played, and continues to play, a leading role in the engineering and integration efforts of the CMS experiment.

Their participation in CMS is at the core of their mission as research institutions and centres of higher education. PhD students are being educated in these institutions to become future scientific and industry leaders, while having the opportunity to work on constructing and operating such a unique instrument and being immersed in a widely international and collaborative environment conducive to the flow of ideas.

The following groups are involved in the CMS collaboration:

ETH Zurich, Uni Zurich, PSI, Uni Basel (until 2004)

Professors: Günther Dissertori, Ralph Eichler (till 2007), Christophorus Grab, Hans Hofer (emeritus, 2001), Urs Langenegger, Felicitas Pauss, Claude Amsler, Roland Horisberger, Ludwig Tauscher (until 2004) and Dr. Quentin Ingram, Dr. Dieter Renker.

Special retransmission at the ETH Zurich

Live-Video-Broadcast: Wednesday, 10. September, on ETH-Life as well as in the Auditoriums HG D16.2 (ETH Zentrum) and HCI J3 (ETH Hönggerberg):
12:00 to 12:25: Press-conference from CERN (in English and French) of the CERN Director general Robert Aymar and the LHC project leader Lyn Evans.
12:30 to 13:00: Live from the Centre of the CMS detector, with scientists from ETH Zurich and the Paul Scherer Institute and University of Zurich commenting the event