Fig. 2.

Simulated COSINUS data in the light yield versus energy plane for a detector reaching the performance goals presented in Ref. [7] and assuming a background level compatible with DAMA/LIBRA: a flat electromagnetic background of 1 $\text{cts}{\text{kg}}^{-1}{\text{d}}^{-1}{\text{keV}}^{-1}$ and an internal ${}^{40}$K contamination of 600 $\mathrm{\mu }$Bq/kg responsible for the line at $\sim$ 3 keV. The solid lines mark the upper and lower 90 % boundaries of the e${}^{-}$/$\gamma$-band (black) and the nuclear recoil bands for recoils off sodium (blue) and iodine (green), respectively. This plot is based on the energy-dependent quenching factors reported in Ref. [11]. Plot adopted from Ref. [7]