Left to right: Dr Claudiu Cojocaru, on secondment to the BIPM from the NRC (Canada), Prof. Manuella Vincter (CERN) and Dr Steven Judge (BIPM).

The ATLAS experiment at CERN ( https://atlas.cern/) is one of the largest and most complex scientific instruments ever constructed. The aim of the experiment is to study the fundamental properties of matter, leading to a better understanding of our world and the history of our universe.

The BIPM was very pleased to welcome Prof. Manuella Vincter from CERN, on 29 July 2019, to give a seminar on the experiment. Prof. Vincter explained the objectives of the experiment and some of the technical challenges. Charged particles travelling at nearly the speed of light are collided at the centre of the instrument - these conditions replicate the time shortly after the Big Bang. Sub-atomic particles are thrown out in the collision and detected in the ATLAS experiment, which has multiple layers of detectors to identify the different particles. The instrument itself is 46 m long, 25 m in diameter and weighs 7000 tonnes (the same weight as the Eiffel tower). Prof. Vincter explained the care needed to ensure the calibration of the detectors and the estimation of uncertainties.

ATLAS is currently being upgraded to measure the particles produced at even higher collision energies, which could lead to the discovery of unknown sub-atomic particles and new physics. As well as pushing the boundaries of our knowledge, the experiment leads to new technologies for radiation detection and data handling (which, in the long term, may have applications in metrology).

Prof. Vincter is a deputy director of the ATLAS experiment and is a Fellow of the Royal Society of Canada.