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A success story from Italian physics
The expertise of the Italian physicists and industry is behind the strongest magnet ever built in the world, which is being positioned today in the seat of what will become the greatest man-made machine ever: the LHC (Large Hadron Collider) particle accelerator at CERN in Geneva. Today’s magnet is part of the Compact Muon Solenoid experiment and its heart was designed and carried out with the decisive contribution of the Italian National Institute for Nuclear Physics and built mostly by the Italian industry.
The Italian physics referring to the National Institute for Nuclear Physics (INFN) is a crucial part of the great technical-scientific endeavour that is taking place in these hours in Geneva, in the seat of CERN, the European particle laboratory.
From 6 a.m. this morning until late at night, an important part of the Compact Muon Solenoid (CMS) is being lowered with every possible precaution into the gigantic underground “canal”, 27 kilometres long (and buried 100 metres deep under the suburbs of Geneva) where LHC, the next, extremely powerful particle accelerator is being built.
The part lowered – called Yoke Barrel 0 - is 16 metres in height and 13 metres long. Its weight is 2.000 tons and it must be inserted into its seat with no damage whatsoever because it is part of a
N instrument that is as precise as it is powerful.
The magnet of the CMS experiment holds the record of stored energy: its magnetic field measured 4 Tesla, equivalent to 80.000 times the magnetic field of the earth. The magnetic forces generated are consequently extremely high: it’s as if there were 15.000 tons (the equivalent of a heavy cruiser ship) leaning onto the external walls of the magnet (solenoid).
In order to obtain these performances, the magnet will be superconductive and it will have to function at an extremely low temperature: just 4,2 degrees above the absolute zero (around minus 269 degrees centigrade), practically the lowest temperature in the universe.
Once completed, CMS will weigh 12.500 tons and it will be 21 metres long.
The task of the experiment will be to study the properties of the particles that will be produced when proton beams will collide at extremely high energies inside the LHC accelerator.
The Italian contribution is an important one: the INFN, and the Genoa division in particular, have proven decisive in their contributions to the design both of the conductor and, especially, of the coils. The competition to realize this last part was won by the Italian ASG Superconductor (ex Ansaldo group) that built it under the INFN’s supervision.
Also Italian are the muon chambers, the tracer and part of the electromagnetic calorimeter that complete the detector of CMS.
The final setup of the experiment will end on the next 22 March, when a conclusive party will be held to celebrate the event in Geneva.
Roberto Petronzio, president of the INFN: “These objects are so big because they have to carry out the immensely difficult task of bending the path of particles that have extremely high energy levels. Once more technology is pushed to its uttermost frontiers by the thrust towards knowledge that comes from basic research in physics”.
Pasquale Fabbricatore, responsible at INFN for the design of the magnet: “The construction of this magnet has required on our part the development of a project which was then tested for feasibility by industry. This is an example of the collaboration between science and industry: for eight years public researchers and private technicians have worked side by side at a great technological-scientific endeavour”.
Sergio Bertolucci, vice-president of INFN: “This is an exciting moment because it’s really now that the heart of the experiment is being lowered into its final position. The experiment is made of the largest superconducting magnet ever built and its heart weighs more than 2000 tons… just imagine, as much as more than 1500 powerful cars!”
Umberto Dosselli, member of the board at INFN: “Today one of the most important phases of the Cms experiment is complete: the heart of the experiment itself will be lowered into the experimental zone, and this is also a reason for national pride, since it was constructed in Italy under the supervision of the INFN”.
In a nutshell:
* The supermagnet of the CMS experiment will be lowered today into its niche 100 metres deep at CERN in Geneva.
* The operation will last more than 12 hours.
* The CMS supermagnet is the fruit of a vast international collaboration between the National Institute for Nuclear Physics, CERN and other research centres in Europe.
* The spools of the supermagnet were built by ASG Superconductor under the supervision of the researchers of the National Institute for Nuclear Physics.
* The supermagnet is formed by five gigantic spools of 250 tons each which generate a magnetic field of 4 Tesla, as much as 80.000 times stronger than the earth’s magnetic field.
* The supermagnet develops a magnetic force equalling 14.000 tons
* The CMS experiment will study the properties of the particles produced in the collisions between proton beams circulating inside the LHC accelerator which will start functioning in the second half of 2007.