Prof. Dr. Karoline Schäffner, Max-Planck-Institut für Physik
Garching Three Decades of Dark Matter Annual Modulation Searches with NaI
Detectors: Overview and Current Status of COSINUS
Prof. Dr. Karoline Schäffner
Max-Planck Institut und TU / München - Garching
The search for an annual modulation in the event rate induced by the Earth’s motion
through the Galactic dark matter halo provides a powerful tool for discriminating
potential dark matter signals from detector backgrounds. The DAMA/LIBRA
experiment, a pioneer in exploiting this signature, has observed a modulated signal with
very high statistical significance, exhibiting a period and phase consistent with dark
matter expectations. However, these results remain in strong tension with the null results
of most other direct detection experiments, and a fully model-independent experimental
verification has still not been achieved.
COSINUS aims to address this long-standing puzzle by operating sodium iodide crystals
as cryogenic scintillating calorimeters. Compared to other NaI-based searches, COSINUS
offers several distinctive features: a low nuclear-recoil energy threshold, superior energy
resolution, and event-by-event particle identification.
In this seminar, I will review the current global program of NaI-based dark matter
searches and focus on the status of the COSINUS experiment. I will present recent results
from the COSINUS prototype detector, describe the development of the dedicated lowbackground cryogenic facility at the Gran Sasso National Laboratory, and outline the
ongoing commissioning toward the first physics data-taking campaign planned to start
mid 2026. To conclude, I will discuss the remaining experimental challenges and the
open questions that continue to keep this enduring puzzle unresolved.
