Any experiment aiming to measure coherent elastic neutrino-nucleus scattering (CEvNS) via nuclear recoils in cryogenic bolometers relies crucially on a precise detector calibration at sub-keV energies.
CRAB proposes a new calibration technique relying on the capture of thermal neutrons inside the target crystal. The subsequent emission of $\gamma$-rays of O(10 MeV) induces nuclear recoils at the O(100 eV) scale. Extensive simulations with Geant4, extended by FIFRELIN for high-precision nuclear de-excitation, predict sharp calibration peaks of nuclear recoils in this regime. This unique feature of the CRAB technique makes it an ideal calibration method.
Currently in its R&D phase, CRAB is developing the experimental setup based on a cryogenic CaWO4 bolometer. Afterwards, precision measurements at the TRIGA nuclear reactor at TU Wien are planned. Additional tagging of the associated $\gamma$-rays increases the sensitivity of this method and extends its application to other materials such as Ge or Si as well as quenching factor measurements.
In this contribution we report the status of the R&D efforts and give an outlook on the impact on the field of cryogenic bolometry.