After a year of characterization and instrumentation, the Ricochet cryostat took up residence at the Institut Laue-Langevin (ILL) in Grenoble in early December 2023. It is installed 8.8 meters from the core of the 58.3 MWth nuclear research reactor, after more than 2 years of site preparation including the installation of its 20-tonne shielding.
Just two months after its installation at ILL began, the first heat and ionization signals were observed with 42 g germanium bolometers, confirming on site the performances obtained during their qualification in 2023.
shielding and open cryostat with installation of a miniCryoCube on its “remote 10 mK” stage (center), zoom on the miniCryoCube (right).
The aim of the Ricochet experiment [1] is to measure neutrino-nucleus elastic coherent scattering (CEνNS) with one-percent accuracy, in order to explore possible openings into physics beyond the Standard Model. The Ricochet collaboration brings together French, Russian and North American laboratories. The French laboratories are developing cryogenic germanium detectors with dual heat and ionization measurement, based on NTD-Ge (Neutron Transmutation Doped Ge) technology for heat measurement, while the American and Canadian collaborators are developing cryogenic superconducting zinc and aluminum detectors with TES (Transition Edge Sensor) technology.
After reaching 8.7 mK on February 6, 2024, when the cryostat was chilled for the first time, Ricochet entered the commissioning and finalization phase of its installation in February, with the first miniCryoCube (an assembly of three germanium detectors) operational. The next few months will be devoted to fine-tuning cryogenic and electronic performance, as well as optimizing external and internal shielding, for both the ON and OFF phases in 2024.
Initial scientific feedback is expected by the end of the year, and during 2025 the experiment should accommodate a total of 750 g of germanium detectors and 300 g of Zn and Al detectors, to accumulate data over at least 7 ON/OFF reactor cycles.
Russie : JINR
USA : University of Massachusetts at Amherst, MA ; Massachusetts Institute of Technology, MA ;
Northwestern University, IL
Canada : University of Toronto, ON