MINER reactor based search for axionlike particles using sapphire (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mtext>Al</mml:mtext><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml

The absence of definitive results for WIMP dark matter has sparked growing interest in alternative dark matter candidates, such as axions and axionlike particles (ALPs), which also provide insight into the strong CP problem. The Mitchell Institute Neutrino Experiment at Reactor (MINER), conducted at the Nuclear Science Center of Texas A&amp;M University, investigated ALPs near a 1 MW h TRIGA nuclear reactor core, positioned approximately 4 m away. This experiment employed cryogenic sapphire detectors with a low detection threshold (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo>≈</a:mo><a:mn>100</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>eV</a:mi></a:math>), equipped with a transition edge sensor capable of detecting athermal phonons. Due to the low-background environment, we were able to exclude ALPs with axion-photon coupling and axion-electron coupling as small as <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msub><c:mi>g</c:mi><c:mrow><c:mi>a</c:mi><c:mi>γ</c:mi><c:mi>γ</c:mi></c:mrow></c:msub><c:mo>=</c:mo><c:msup><c:mn>10</c:mn><c:mrow><c:mo>−</c:mo><c:mn>5</c:mn></c:mrow></c:msup></c:math> and <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>g</e:mi><e:mrow><e:mi>a</e:mi><e:mi>e</e:mi><e:mi>e</e:mi></e:mrow></e:msub><e:mo>=</e:mo><e:msup><e:mn>10</e:mn><e:mrow><e:mo>−</e:mo><e:mn>7</e:mn></e:mrow></e:msup></e:math>, respectively. Energy depositions below 3 keV were not considered and remain blinded for our coherent elastic neutrino-nucleus scattering analysis. This is the first result demonstrating the MINER experiment’s potential to probe low-mass ALPs, enabled by its low-threshold detector and proximity to a reactor.