Resumen: We report the first result from a dark photon dark matter search in the mass range from 78.62 to 83.95 μeV/c2 with a dielectric haloscope prototype for (Magnetized Disc and Mirror Axion eXperiment). Putative dark photons would convert to detectable photons within a stack consisting of three sapphire disks and a mirror. The emitted power of this system is received by an antenna and successively digitized using a low-noise receiver. No significant signal attributable to dark photons has been observed above the expected background. Assuming unpolarized dark photon dark matter with a local density of ρχ=0.3 GeV cm3 we exclude a dark photon to photon mixing parameter χ>2.7×10−12 over the full mass range and χ>1.1×10−13 at a mass of 80.57 μeV/c2 with a 95% confidence level. This is the first physics result from a prototype and exceeds previous constraints on χ in this mass range by up to almost three orders of magnitude. Idioma: Inglés DOI: 10.1103/PhysRevLett.134.151004 Año: 2025 Publicado en: Physical Review Letters 134, 15 (2025), 151004 [7 pp.] ISSN: 0031-9007 Financiación: info:eu-repo/grantAgreement/ES/DGA-FSE/E21-17R Financiación: info:eu-repo/grantAgreement/ES/MICINN/PGC2022-126078NB-C21 Tipo y forma: Artículo (Versión definitiva) Área (Departamento): Área Física Teórica (Dpto. Física Teórica)