First Results on Dark Matter Annual Modulation from the ANAIS-112 Experiment.

Area of Science:

• Particle Physics
• Astroparticle Physics
• Cosmology

Background:

• The DAMA/LIBRA experiment has reported evidence for dark matter annual modulation for two decades.
• No other experiment has independently confirmed or refuted these findings in a model-independent manner.
• Direct detection experiments aim to observe dark matter particles interacting with terrestrial detectors.

Purpose of the Study:

• To independently test the DAMA/LIBRA annual modulation result using the ANAIS-112 detector.
• To search for model-independent evidence of dark matter annual modulation.
• To validate the sensitivity projections of the ANAIS experiment.

Main Methods:

• Utilized 112.5 kg of sodium iodide crystals in the ANAIS-112 detector.
• Collected and analyzed 1.5 years of data, totaling 157.55 kg yr exposure.
• Performed a model-independent analysis searching for annual modulation in the [1-6] keV and [2-6] keV energy regions.

Main Results:

• ANAIS-112 data are consistent with the null hypothesis (no modulation) with high p-values (0.67 and 0.18).
• Best-fit modulation amplitudes (S_m) are consistent with zero, within uncertainties.
• Observed results align with the experiment's projected sensitivity for dark matter detection.

Conclusions:

• The ANAIS-112 experiment's findings do not support the DAMA/LIBRA annual modulation signal.
• The experiment validates its sensitivity projections, supporting the goal of reaching 3σ sensitivity within five years.
• Further data collection and analysis are crucial for a definitive conclusion on dark matter annual modulation.