Cryogenic characterization of a $$\hbox {LiAlO}_{2}$$ crystal and new results on spin-dependent dark matter interactions with ordinary matter

In this work, a first cryogenic characterization of a scintillating LiAlO2 single crystal is presented. The re- sults achieved show that this material holds great potential as a target for direct dark matter search experiments. Three different detector modules obtained from one crystal grown at the Leibniz-Institut für Kristallzüchtung (IKZ) have been tested to study different properties at cryogenic tempera- tures. Firstly, two 2.8 g twin crystals were used to build dif- ferent detector modules which were operated in an above- ground laboratory at the Max Planck Institute for Physics (MPP) in Munich, Germany. The first detector module was used to study the scintillation properties of LiAlO2 at cryo- genic temperatures. The second achieved an energy thre- shold of (213.02±1.48) eV which allows setting a competi- tive limit on the spin-dependent dark matter particle-proton scattering cross section for dark matter particle masses be- tween 350 MeV/c2 and 1.50 GeV/c2. Secondly, a detector module with a 373 g LiAlO2 crystal as the main absorber was tested in an underground facility at the Laboratori Nazio- nali del Gran Sasso (LNGS): from this measurement it was possible to determine the radiopurity of the crystal and study the feasibility of using this material as a neutron flux moni- tor for low-background experiments.