Sodium iodide (NaI) is a widely used scintillator in direct dark matter searches. In particular, NaI-based cryogenic scintillating calorimeters have emerged as promising candidates, like in the COSINUS experiment, for testing the annually modulating signal reported by DAMA/LIBRA. In this study, we investigate defect formation within NaI crystals and its impact on the dark matter detection signal. Using molecular dynamics simulations and density functional theory techniques, we simulate a DM particle collision on an NaI crystal, focusing on the possible defects formation and their structural and electronic properties. Our analysis includes a detailed study of the electronic states associated with the interstitial atoms and vacancies, the energetic cost of defect formation, and the anisotropic threshold displacement energy. Finally, we highlight the potential to exploit dark matter-induced defects as a novel detection channel, enabled by the introduction of new states within the electronic band gap.
@article{arxiv.2512.23553,
title = {Defect Formation in NaI Crystals: A Novel Pathway to Dark Matter Detection},
author = {G. Angloher and M. R. Bharadwaj and A. Böhmer and M. Cababie and I. Colantoni and I. Dafinei and N. Di Marco and C. Dittmar and F. Ferella and F. Ferroni and S. Fichtinger and A. Filipponi and T. Frank and M. Friedl and D. Fuchs and L. Gai and M. Gapp and M. Heikinheimo and M. N. Hughes and K. Huitu and M. Kellermann and R. Maji and M. Mancuso and L. Pagnanini and F. Petricca and S. Pirro and F. Pröbst and G. Profeta and A. Puiu and F. Reindl and K. Schäffner and J. Schieck and P. Schreiner and C. Schwertner and P. Settembri and K. Shera and M. Stahlberg and A. Stendahl and M. Stukel and C. Tresca and S. Yue and V. Zema and Y. Zhu and N. Zimmermann and M. Di Giambattista and F. Giannessi and R. Rollo},
journal= {arXiv preprint arXiv:2512.23553},
year = {2026}
}