We present results of a search for spin-independent dark matter-nucleus interactions in a by 1 mm thick (0.233 g) high-resolution silicon athermal phonon detector operated above ground. For interactions in the substrate, this detector achieves an rms baseline energy resolution of (statistical error), the best for any athermal phonon detector to date. With an exposure of hours, we place the most stringent constraints on dark matter masses between 44 and , with the lowest unexplored cross section of at . We employ a conservative salting technique to reach the lowest dark matter mass ever probed via direct detection experiment. This constraint is enabled by two-channel rejection of low energy backgrounds that are coupled to individual sensors.
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This content will become publicly available on September 1, 2026
Search for axionlike dark matter using liquid-state nuclear magnetic resonance
We search for dark matter in the form of axionlike particles (ALPs) in the mass range by probing their possible coupling to fermion spins through the ALP field gradient. This is achieved by performing proton nuclear magnetic resonance spectroscopy on a sample of methanol as a technical demonstration of the Cosmic Axion Spin Precession Experiment Gradient (CASPEr-Gradient) Low-Field apparatus. Searching for spin-coupled ALP dark matter in this mass range with associated Compton frequencies in a 240 Hz window centered at 1.348570 MHZ resulted in a sensitivity to the ALP-proton coupling constant of . This narrow-bandwidth search serves as a proof-of-principle and a commissioning measurement, validating our methodology and demonstrating the experiment’s capabilities. CASPEr-Gradient Low-Field will probe the mass range from to with hyperpolarized samples to boost the sensitivity beyond the astronomical limits.
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- PAR ID:
- 10652417
- Publisher / Repository:
- American Physical Society
- Date Published:
- Journal Name:
- Physical Review D
- Volume:
- 112
- Issue:
- 5
- ISSN:
- 2470-0010
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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