ATLAS

Mar 24, 2023

ATLAS observes for the first time the production of 4 top quarks

The ATLAS collaboration announced at the Moriond conference the observation of simultaneous production of four top quarks. This is one of the rarest and heaviest processes ever observed at the Large Hadron Collider (LHC). This measurement, coordinated by IRFU, allows to test the Standard Model of particle physics in its most complex predictions. Link to the ATLAS collaboration publication

Jun 28, 2021

ATLAS giants on their way to CERN!

As part of the luminosity increase of the Large Hadron Collider (LHC), the first phase of the ATLAS experiment upgrade is coming to an end, before a restart planned for early 2022. To meet the requirements of physics in a highly radiative environment with a high particle flux, the two internal wheels of the muon spectrometer will be replaced by new devices: the New Small Wheels (NSW).

More

Mar 10, 2021

Paris-Cluster qualified!

The ATLAS detector equipped with a new charged particle tracking device for the HL-LHC.

The high luminosity phase of the LHC (HL-LHC) should enable the collection of a dataset unprecedented in the history of particle physics. In order to record these data, the Atlas detector will undergo a major upgrade. IRFU, via the Paris-Cluster in synergy with two other laboratories in Ile de France, is committed to the construction of a part of the internal tracker.

More

Aug 03, 2020

ATLAS: from photon collisions to axions

Photon-photon elastic scattering is a very rare phenomenon in which two real photons interact producing a new real photon pair. The direct observation of this process at high energy, impossible during decades, was done by ATLAS [1] and CMS [2] experiment at CERN between 2016 and 2019. These successes have led the two collaborations to strengthen their involvement in this new field, leading to a new measurement, currently being published by the ATLAS experiment [3].

More

Jun 19, 2018

Heavy weights wedding

The ATLAS and CMS collaborations, involving teams from CEA/IRFU and CNRS/IN2P3, announced on 4 June 2018 at the LHCP conference the direct observation of the coupling of the quark top to the Higgs boson. Studying the interaction between the Higgs boson and the heaviest elementary particle known, the quark top, is a way of investigating the effects of new physics, which must take over from the standard model.

More

Nov 09, 2017

Do the two heavy weights of the Standard Model associate with each other?

The LHC's Atlas collaboration at Cern has observed a rare process: the production of Higgs bosons in association with a top quark and top antiquark pair. This work, supervised by an Irfu researcher, opens up perspectives on the study of the Higgs mechanism that gives mass to particles.

Oct 19, 2017

Top quark at the LHC: no new physics in sight yet!

Data collected at the LHC (Cern) were processed to provide the most accurate assessment of an asymmetry in top quark and top antiquark production. The result is that the measured value is compatible with the prediction of the standard particle model.

Aug 16, 2017

Playing Pool with Photons at the LHC

The ATLAS collaboration at CERN's LHC has found the first direct evidence for the rare process of high-energy light-by-light scattering, where two photons interact and change direction. This phenomenon was predicted several decades ago by quantum electrodynamics, i.e. the quantum theory of electromagnetism.

Jul 07, 2017

ATLAS Experiment at LHC: the Higgs Boson, Still Unique

Physicists from IRFU have announced that no "big brother" of the Higgs boson has been detected at the ATLAS experiment at CERN's LHC. Their results rely on new analyzes with higher sensitivity.

Feb 08, 2017

First Observation of Light-by-light Scattering at the LHC

Light-by-light scattering, predicted in 1936, was observed for the first time by the ATLAS experiment at the LHC, thanks to "ultra-peripheral" collisions of lead ions. It is of particular interest to physicists, as it is the result of interactions between a vacuum and intense electromagnetic fields.

Division of Electronics, Detectors and Computing for Physics (DEDIP)

Institute of Research into the Fundamental Laws of the Universe