The ultimate constituents of matter
The ultimate constituents of matter

Design of these toroidal magnets and of the mechanical structure of Atlas is but one contribution by Dapnia to this detector, here being mounted at Cern.

Research on the elementary constituents of the Universe is a strong focus of Irfu's activities.

The groups are actors in the ATLAS and CMS projects at the LHC and are invested in the design of future collider projects.

In the bestiary of elementary particles, the neutrino is an enigma in itself and many projects are at work with reactors, sources and accelerators, to discover its mysteries and unravel those of the new physics beyond the standard model.

The 3rd path is that of low energy with precise measurements of decay β and a measure of antimatter response to gravity.

#528 - Last update : 06/08 2018

Powerful fundamental interaction tests can be performed in the low energy domain, usually in the form of high precision measurements.

At Irfu, this theme corresponds to two activities:

         - on the one hand, high-precision measurements of nuclear decay β at GANIL,

        - on the other hand to measure the movement of antihydrogen atoms in the Earth's gravitational field, i.e. a free fall experiment for antimatter.


The  physics of neutrinos is studied using different sources such as reactors, accelerators and radioactive sources.

The objectives of these experiments are:

   - to measure all neutrino oscillation parameters by varying their energies and oscillation distance and measure their mass. These measurements could be related to phenomena beyond the standard particle physics model: for example new interactions, or the existence of new particles.

   - to precisely measure the difference in propagation of neutrinos and antineutrinos in order to quantify the violation of charge-parity symmetry (CP) by neutrinos. This could shed light on the origin of the asymmetry between matter and antimatter in the Universe.

   - to measure a very rare beta disintegration, called double beta without neutrino (named "ββ0ν"), which would prove that the neutrino could have a different nature from the other particles of matter and be identical to its own antiparticle.

scheme of the DUNE experiment in the United States (left), cryostat under construction in 2014 of the CUORE experiment in Italy (right)

The DPhP Atlas and CMS groups actively contributed to the first accurate measurements of the Higgs boson properties in the decay channel in two Z bosons, for the Atlas group, and two photons for the CMS group.

The tests of the standard particle physics model with precision measurements on the W mass  for example, and the direct search for new physics are the two approaches to find the new physics in the data collected from particle colliders.

With the increase in luminosity and energy, research is also focused on studies of rare events such as the search for the Higgs production associated with a pair of top quarks (ttH).


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