Speaker
Description
The current generation of cryogenic solid state detectors used in direct dark matter and CE$\nu$NS searches typically reach energy thresholds of $\mathcal{O}$(10$\,$eV) for nuclear recoils. The energy calibration of these detectors is usually done via X-ray sources with energies in the $\mathcal{O}$(keV) region, requiring an extrapolation to the low-energy regime. Ideally, these detectors should be calibrated via mono-energetic nuclear recoils in the relevant energy range. To achieve this, a new method has been proposed which is based on the radiative capture of thermal neutrons on nuclei, which may be followed by a de-excitation via single $\gamma$-emission leading to a low-energetic nuclear recoil. The first experimental observations of this effect were accomplished with $_{4}$ crystals. In this work we report on the observation of a peak around 1.1$\,$keV in the data of an Al$_{2}$O$_{3}$ crystal in CRESST-III, which was irradiated with neutrons from an AmBe calibration source. We attribute this mono-energetic peak to the radiative capture of thermal neutrons on $^{27}$Al and the subsequent de-excitation via single $\gamma$-emission.
To investigate the impact of crystal defect creation on the observable energy, the INCIDENCE project is performing molecular dynamics simulation of the Al recoil within the crystal lattice of Al$_{2}$O$_{3}$. We will present first results that predict an energy loss of $\mathcal{O}$(10$\,$eV) for nuclear recoils at around 1.1$\,$keV.
