​"With Double Chooz, we were the leaders in reactor neutrino experiments," says physicist Thierry Lasserre, who started this ambitious project. "Then Korea, Japan, and China copied us and exceeded our objectives." Yet the results are there: neutrinos can transform (or "oscillate") in three distinct forms over time.

"Although we only had a single detector, we realized in 2010 that the calculations on neutrino production carried out up to that point were wrong! And the results that had been previously published became incomprehensible... The community finally admitted what has been called the reactor neutrino anomaly." Then an explanation emerged: a fourth, short-distance oscillation would produce "inert" (or sterile) neutrinos.

"To go further, we came up with the idea of creating a mobile source of neutrinos to collect several measures using a single detector instead of two measures using two detectors, as in Double-Chooz." This was yet another challenge! Lasserre had to travel all the way to Russia to find a used fuel reprocessing plant for a supplier of a capsule of 30 g of radioactive cerium-144, a source of antineutrinos. This will be the first source of its kind and a completely unprecedented structure in terms of its regulatory framework. It has already required all forms of nuclear expertise represented at the CEA Nuclear Energy Division. More information will be available in 2018!

An unexpected neutrino and a much-expected boson

As the sterile neutrino entered the scientific debate, the Higgs boson that kept physicists in suspense for decades was discovered in 2012. And in fact it continues to raise questions. Does it match the Standard Model? To find out, a team of researchers is responsible for optimizing the CMS experiment observations of the very rare events in which the Higgs boson interacts strongly with an exceptionally heavy particle—the top quark. "A significant difference between the measurement of the probability of such events and the prediction of the Standard Model would indirectly point to a new physics," said Inna Kucher, a Ukrainian Ph.D. student in the group. "Although we still can't reach conclusions based on 2015 data, 10 times more data will be collected by the end of 2016, which should provide the very first significant results." Stay tuned!