Tests and extensions of the Standard Model (SPP)

Atlas electromagnetic calorimeter. : the first half of the barrel calorimeter in its cryostat and the 55000 signal cables connected to their feed-throughs distributed around the
cryostat.

This program covers the experiments at accelerators with the top beam energy in the world. At Cern close to Geneva , the LEP was a large electron-positron collider, in operation from 1989 to 2000. It allowed a very detailed exploration of the Standard Model, with outstanding results, such as the measurement of the number of neutrino species -3-, or the indirect measurement of the top quark mass, and a large range of precision measurements. The last phase of operation has set important limits on the possibilities of physics beyond the Standard Model. Two groups from SPP participated to large experiments: Aleph and Delphi.

LHC is the future proton collider at Cern, scheduled for operation starting 2007. As soon as 1984, the possibility of building a very high energy (14 TeV) proton accelerator in the LEP tunnel, was felt as an extraordinary potential for the physics of the elementary. Studies show that the LHC will be able to deal directly with the big questions of the Standard Model and of its possible extensions. This accelerator and the associated experiments are very large projects which gather all the world community. Dapnia has a strong contribution to the machine and to the physics experiments. SPP physicists were involved ever since the origin of the project, and have had an essential role in the birth of both large general purpose experiments: Atlas and Cms. Both groups are now quite sizeable in SPP.

CMS : The fl ux return of the solenoid during assembly.

Atlas : Simulated event represented graphically using the PERSINT visualisation code.
This programme allows removing or adding detector parts to improve the view, changing its orientation, etc…

In Fermilab (Chicago, USA), the “Tevatron” has been colliding protons and antiprotons at 2 TeV since 1983. A group from SPP is a member of the D0 collaboration. Research topics include precise measurements of the Standard Model (top quark and W boson), and some possibility for new physics discovery. It is also a good training ground for the analysis of LHC data. In Desy (Hamburg, Germany), the HERA accelerator has been colliding protons and electrons since 1992. The point like electron is used there to probe the structure of the proton. This also allows to look for signs of physics outside the Standard Model. A small group from SPP is a member of the H1 collaboration.

#569 - Last update : 07/22 2005

Nuclear Physics Division

Institute of Research into the Fundamental Laws of the Universe