The Tevatron CDF and D0 collaborations have just received the 2019 Prize for Particle and High Energy Physics awarded by the European Physical Society for the discovery of the top quark in 1995 and the detailed measurements of its properties from 1995 to the present. This prize thus rewards the physicists and engineers of the Irfu who contributed to the construction of the D0 detector, the discovery of the quark top, and conducted numerous studies on top quark physics.
The Tevatron is proton-antiproton collider that was commissioned in 1986 at Fermilab near Chicago (USA). At that time, the existence of the top quark was predicted as a member of the 3rd family of elementary fermions of the standard model of particle physics. While its hunt began in the late 1970s, it was the Tevatron's D0 and CDF experiments in 1995 that discovered the most massive elementary particle ever observed, almost as heavy as a gold atom. Its large mass makes it play a very special role in the bestiary of the standard model. For example, it has a very strong interaction with the Higgs boson and could be involved in the Higgs mechanism of electroweak symmetry breaking responsible for the mass of elementary particles. In general, its large mass also allows the standard model to be tested at TeV energy scale, where new phenomena could occur.
After the discovery, as the statistics of detected top quarks increased, its properties could be measured and tested, including: mass, life time, spin, charge, production mechanism, decay modes. The Tevatron Run II from 2001 to 2011 increased the statistics by a factor of 100, opening up the possibility of precision measurements. The top quark continues to be studied nowadays at LHC, which is an actual top quarks factory.
The teams from Irfu, at the time « DPhPE », participated in the construction of D0 in the late 1980s by developing one of its subdetector, the TRD (transition radiation detector). They then participated in the discovery of the quark top.
At Run II, the Irfu physicists played a major rôle. On the one hand they lead numerous studies on the top quark: measurements of the mass and the production cross-section, tests of electroweak production, measurements of production asymmetries, spin, and polarization, measurements of the coupling to the W boson. On the other hand they coordinated the activities of D0 top group from 2008 to now.. The prize awarded by the European Physical Society thus rewards several generations of engineers, physicists and doctoral students from Irfu. This prize was just received during the EPS-HEP International Conference in Ghent, Belgium on July 15.
For more information:
Citation for the EPS-HEP prize: link to the pdf
Publications and thesis at Irfu about top quark: link
Contact: Boris Tuchming