First Limits on Light Dark Matter Interactions in a Low Threshold Two-Channel Athermal Phonon Detector from the...

Area of Science:

• Particle Physics
• Astrophysics
• Cosmology

Background:

• Direct detection experiments aim to observe dark matter particles interacting with ordinary matter.
• Athermal phonon detectors offer high sensitivity for detecting low-energy interactions.
• Previous experiments have explored various mass ranges and interaction types for dark matter.

Purpose of the Study:

• To search for spin-independent dark matter-nucleus interactions using a silicon athermal phonon detector.
• To establish new stringent constraints on dark matter particle masses and cross sections.
• To probe the lowest dark matter masses to date in direct detection experiments.

Main Methods:

• Utilized a 1 cm² by 1 mm thick silicon athermal phonon detector operated above ground.
• Achieved an exceptional rms baseline energy resolution of 361.5(4) meV.
• Employed a conservative salting technique and two-channel background rejection for low-energy events.

Main Results:

• Achieved the best energy resolution for any athermal phonon detector to date.
• Set the most stringent constraints on dark matter masses between 44 and 87 MeV/c².
• Established a new lowest unexplored cross section of 4×10⁻³² cm² at 87 MeV/c².

Conclusions:

• The experiment successfully constrained dark matter properties within a previously unexplored low-mass region.
• The developed techniques demonstrate the potential for future direct detection experiments with enhanced sensitivity.
• This work pushes the boundaries of direct dark matter detection, contributing to our understanding of dark matter composition.