We present results of a search for spin-independent dark matter-nucleon interactions in a 1 cm2 by 1 mm thick (0.233 gram) high-resolution silicon athermal phonon detector operated above ground. For interactions in the substrate, this detector achieves a r.m.s. baseline energy resolution of 361.5 ± 0.4 MeV/c2, the best for any athermal phonon detector to date. With an exposure of 0.233g × 12 hours, we place the most stringent constraints on dark matter masses between 44 and 87 MeV/c2, with the lowest unexplored cross section of 4 ×10−32 cm2 at 87 MeV/c2. 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.
@article{arxiv.2503.03683,
title = {First Limits on Light Dark Matter Interactions in a Low Threshold Two Channel Athermal Phonon Detector from the TESSERACT Collaboration},
author = {C. L. Chang and Y. -Y. Chang and L. Chaplinsky and C. W. Fink and M. Garcia-Sciveres and W. Guo and S. A. Hertel and X. Li and J. Lin and M. Lisovenko and R. Mahapatra and W. Matava and D. N. McKinsey and V. Novati and P. K. Patel and B. Penning and H. D. Pinckney and M. Platt and M. Pyle and Y. Qi and M. Reed and G. R. C Rischbieter and R. K. Romani and B. Sadoulet and B. Serfass and P. Sorensen and A. Suzuki and V. Velan and G. Wang and Y. Wang and S. L. Watkins and M. R. Williams and J. K. Wuko and T. Aramaki and P. Cushman and N. N. Gite and A. Gupta and M. E. Huber and N. A. Kurinsky and J. S. Mammo and B. von Krosigk and A. J. Mayer and J. Nelson and S. M. Oser and L. Pandey and A. Pradeep and W. Rau and T. Saab},
journal= {arXiv preprint arXiv:2503.03683},
year = {2026}
}