What produces the DAMA/LIBRA annual modulation?
This text mentions work from 2024 on. Those parts were partly written without a live literature search and have not been checked by an editor yet.
In plain words
DAMA/LIBRA sees a yearly rise and fall in low-energy events, peaking in late May or early June, but identical-material experiments see nothing. The question is what physical or instrumental effect makes the DAMA rate oscillate.
Precise statement
DAMA/NaI plus DAMA/LIBRA phases 1 and 2 report a single-hit residual rate in NaI(Tl) with amplitude about 0.01 cpd/kg/keV in 2-6 keV electron-equivalent energy (phase 2 alone extends this to 1-6 keV), period 1 yr and phase in late May, consistent within errors with the June 2 dark matter expectation, at $13.7\sigma$ for 2.86 t yr (2021) and $15.3\sigma$ for 3.40 t yr (2026). COSINE-100 and ANAIS-112, with the same target, find amplitudes consistent with zero. An answer identifies the source of the DAMA modulation (dark matter with crystal-specific response, an environmental or detector effect, or an analysis artifact) and demonstrates it quantitatively on DAMA data or an equivalent setup.
What would settle it
Reproduction or elimination of the modulation in a NaI(Tl) setup that matches DAMA's crystals, energy calibration and analysis, together with release and independent analysis of DAMA's absolute rate time series.
Status in the literature
Unverified note: it names recent work and was partly written without a live literature search; it awaits a check by an editor.
In 2025 COSINE-100 and ANAIS-112 combined 3-year data gave amplitudes $-0.0002 \pm 0.0026$ $\left(1-6\,\mathrm{keV}\right)$ and $0.0021 \pm 0.0028\,\mathrm{cpd}/\mathrm{kg}/\mathrm{keV}$ $\left(2-6\,\mathrm{keV}\right)$, and their 6-year data gave $0.0005 \pm 0.0019$ and $0.0027 \pm 0.0021$, excluding DAMA at $4.7\ \text{and}\ 3.5\,\sigma$; DAMA reported $15.3\,\sigma$ in $2-6\,\mathrm{keV}$ with $3.40\,\mathrm{t}\,\mathrm{yr}$ in 2026 (Nucl. Phys. At. Energy 27, 2026) and identifies no systematic.
Problems built on this one
Special cases
- Can DAMA's background subtraction create a spurious yearly modulation? · open
- Does crystal-specific NaI(Tl) response hide a DAMA-only signal? · open
- Are DAMA-region NaI events nuclear or electron recoils? · open
- Does a Southern Hemisphere NaI detector see the same-phase modulation? · open
Results
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