| On site at CERN 2008 |
The ATLAS experiment is designed to observe phenomena that involve highly massive particles which were not observable using earlier lower-energy accelerators.
By Amanda Jaffe-Katz
“ATLAS,” says Technion Prof. Shlomit Tarem, “is the biggest experiment searching for the smallest things.” She is referring to the biggest of the six particle detector experiments constructed at the Large Hadron Collider (LHC), a particle accelerator at CERN (European Organization for Nuclear Research) in Switzerland.
  First high-energy proton beams circulated
in both directions, observed at ATLAS.
Altogether, the ATLAS collaboration encompasses some 2,500 physicists, engineers, and students at 169 institutions in 37 countries. Alongside Tarem at Technion’s Faculty of Physics, Prof. Yoram Rozen is also involved in this international project, together with graduate students, a postdoctoral fellow, and a technical team. The Technion group works together with scientists from Weizmann Institute and from Tel Aviv University. The Israeli squad cooperates with Japanese teams.
Tarem spends about half her time at CERN, where she also oversees detector control for another three groups. Usually one of the Technion graduate students is there, as is the postdoctoral researcher Dr Sofia Vallecorsa.
The ATLAS experiment is designed to observe phenomena that involve highly massive particles which were not observable using earlier lower-energy accelerators. The scientists anticipate that their findings will shed light on plausible new theories of particle physics beyond the Standard Model, which holds that all matter is composed of 12 particle types that belong to two families: leptons and quarks. It predicts one more yet-to-be-observed particle - the Higgs boson.
 Technion High Energy Experimental physicists at
CERN. (l-r) Shikma Bressler, Prof. Shlomit Tarem,
Alon Hershenhorn, and Sagi Ben-Ami.
“Higgs may be too massive to have been produced previously at a particle accelerator,” Tarem explains, “but in ATLAS, where the energy is seven times higher than that at former accelerators, this excuse is no longer applicable.” The best way to find Higgs is when it decays into four muons. “If we don’t find Higgs then it doesn’t exist, and therefore the Standard Model is not valid.” Conversely, “finding a new particle tells us there is physics beyond the Standard Model. The LHC will bring us to high enough energy so that we can differentiate among new theories,” Tarem says. “Heavy particles decay to lighter ones if the laws of nature so permit. We can recreate them to study nature’s templates,” she says. “We still need to explain Dark Matter and what happened at the time of the Big Bang.”
While no collision events have yet taken place, the particles in the detector were used to debug and set up ATLAS. Tarem explains that even when the LHC is out of action, they are using cosmic rays for ‘commissioning’ - fine tuning, optimization, and making the detector user friendly. “There are at least 10 years of data collection ahead of me,” Tarem concludes. |
|
On site at CERN