Speaker
Description
The RICOCHET experiment aims to measure CEνNS induced by reactor antineutrinos produced by the research nuclear reactor of the Institut Laue-Langevin (ILL) in Grenoble, France. The collaboration employs an array of 42-g germanium cryogenic calorimeters operated at ~15 mK. These calorimeters are instrumented with neutron-transmutation-doped thermistors for the phonon readout and aluminum electrodes for the ionization readout. Two detector designs are used: planar and fully inter-digitized (FID), which differ in their electrode geometry. The FID design enables the identification of surface events, a capability that addresses a previous limitation in estimating the background nuclear recoil rate.
The commissioning of RICOCHET occurred at the ILL throughout 2024 and the first half of 2025. A key objective of this phase was to estimate the rate of background nuclear recoils at keV energies induced by neutrons of reactogenic or cosmogenic origin, which are indistinguishable from the CEνNS signal. The commissioning began with three planar detectors and later expanded to nine detectors, including the first in-situ operation of FID detectors. In this contribution, we report the in-situ measurement of background nuclear recoil rates during the commissioning phase.