CERN Accelerating science

ATLAS

Mighty magnets for particle detectors

The ATLAS Magnet Team, part of the EP-ADO-SO section, has the principal responsibility for the maintenance and operation of the ATLAS Superconducting Magnets. This effort is supported by a large number of colleagues, in particular from EP-DT, TE-CRG…

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LHC takes on the SMEFT challenge

The quest for new physics at the LHC is entering a new phase: the experiments are designing new strategies to target potential deviations from the Standard Model (SM) predictions in a systematic way, to complement the traditional “bump hunts” and,…

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ATLAS faces the challenge of Run 3

The ATLAS experiment is a general-purpose particle detector operating at the LHC. It consists of several concentric layers of particle detectors occupying a cylindrical volume 46m long and 25m in diameter. The innermost detectors reconstruct the…

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The likelihood is dead, long live the likelihood

Among the sciences, particle physics has the luxury of having a well established theoretical basis. Often we focus on the elementary particles and model them mathematically with quantum field theories like the Standard Model. In order to compare…

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CERN's new open data policy supports open science

The four main LHC collaborations (ALICE, ATLAS, CMS and LHCb) have unanimously endorsed a new open data policy for scientific experiments at the Large Hadron Collider (LHC), which was presented to the CERN Council today. The policy commits to…

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Stephanie Zimmermann (1973 – 2020)

  We have been deeply saddened to hear about the passing of Stephanie Zimmermann, an outstanding physicist, who has made a long-lasting contributions to the ATLAS experiment. Stephanie was involved in the Muon Detector Control System activities and…

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Machine learning ushers in a new paradigm for particle searches at the LHC

Searching for physics beyond the Standard Model (BSM) is a major part of the research programme at the LHC experiments. Nearly all of these searches pick a signal model that addresses one or more of the experimental (e.g., dark matter) or…

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What is the likelihood function, and how is it used in particle physics?

In statistical data analysis, “likelihood” is a key concept that is closely related to, but crucially distinct from, the concept of “probability”, which is often a synonym in everyday English. In this article, I first lay some necessary foundations…

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ATLAS New Small Wheel Upgrade – activities resumed after down-time from COVID-19

 As discussed in a previous issue of the EP Newsletter (The ATLAS New Small Upgrade – entering new waters, preparing to install and commission its first sector, October 2019), the New Small Wheel (NSW) Upgrade is the most challenging and complex one…

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CERN experiments find first evidence for rare Higgs boson decay

The strength of the interaction between the Higgs field and a particle determines the mass it obtains from the Higgs and it is a mystery why the interaction strength is different for different particles. This puzzle is exacerbated as the leptons,…

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