Weak-scale dark matter particles, in collisions with nuclei, can mediate transitions between different nuclear energy levels. In particular, owing to sizeable momentum exchange, dark matter particles can enable de-excitation of nuclear isomers that are extremely long lived with respect to regular radioactive decays. In this Letter, we utilize data from a past experiment with Tam180 to search for γ lines that would accompany dark matter induced de-excitation of this isomer. Nonobservation of such transitions above background yields the first direct constraint on the lifetime of Tam180 against dark matter initiated transitions: T1/2>1.3×1014 a at 90% credibility. Using this result, we derive novel constraints on dark matter models with strongly interacting relics and on models with inelastic dark matter particles. Existing constraints are strengthened by this independent new method. The obtained limits are also valid for the standard model γ-decay of Tam180.
Bibliographical noteFunding Information:
We would like to thank Alexey Drobizhev and Vivek Singh for discussions on alternative detector technologies. We also thank Aaron C. Vincent and Ningqiang Song for pointing out a bug in our code that affects the inelastic limits in the previous version by a small amount. This has been corrected in the new version. S. R. was supported in part by the NSF under Grant No. PHY-1638509, the Simons Foundation Grant No. 378243, and the Heising-Simons Foundation Grants No. 2015-038 and No. 2018-0765. H. R. is supported in part by the DOE under Contract No. DE-AC02-05CH11231. The work in HADES by Gerd Marissens, Heiko Stroh, and the Euridice staff is gratefully acknowledged. The measurements were enabled though the Joint Research Centre open access initiative to HADES, Projects No. 21–14.
© 2020 American Physical Society.
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