The ATLAS experiment is installed on the large LHC proton collider at CERN in Geneva. Analysis of data collected at 7 and 8 TeV in 2011-2012 led to the discovery by ATLAS and CMS of a Higgs boson with a mass of 125 GeV. After this first phase, the accelerator moved in 2015-2018 to a second phase, characterized by collisions at 13 TeV and a much higher integrated luminosity. A third data collection began in 2021 for 3 years with significant potential for discovery of physics beyond the standard model. The Higgs boson has become a prominent tool to seek manifestations of physics beyond the Standard Model. The construction of an electron-positron collider acting as a Higgs factory has therefore become a top priority worldwide.

Based on a long-standing global effort, the International Linear Collider (ILC) envisaged to be built in Japan, is a close to construction ready project, currently examined to evaluate its feasibility as an international infrastructure. The design of the machine and of associated detectors as well as the physics potential assessment of the project, have benefited from an international task force where IN2P3 and Japanese research teams have worked in strong collaboration, leading to prominent results in each of the three domains. Major technical issues were addressed, where several orders of magnitude had to be conquered over the state of the art. They concern   the precise and fast beam instrumentation allowing for the ambitioned luminosity using nanobeams and the extremely granular detectors needed for the highly precise reconstruction of the final states produced, complemented with physics studies guiding the detector design.

ILANCE will allow strengthening the partnership in these two domains over a period of time coinciding with new data campaigns for ATLAS and a preparation phase of the ILC project, where the specific contributions of all teams need to be brought together and combined into a real scale design prefiguring an experimental set-up ready for construction. Most intense activities will address the realization of a final demonstrator of a low power and highly granular electromagnetic calorimeter, and of a tracking detector prototype exploiting high resolution thin pixel sensors