Resumen: The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using 3He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with 4He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV≲ma≲0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of gaγ≲2.3×10−10 GeV−1 at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to ma≲1.15 eV, comfortably overlapping with cosmological hot dark matter bounds. Idioma: Inglés DOI: 10.1103/PhysRevLett.107.261302 Año: 2011 Publicado en: Physical Review Letters 107, 26 (2011), 261302 [5 pp.] ISSN: 0031-9007 Factor impacto JCR: 7.37 (2011) Categ. JCR: PHYSICS, MULTIDISCIPLINARY rank: 5 / 82 = 0.061 (2011) - Q1 - T1 Financiación: info:eu-repo/grantAgreement/ES/MICINN/FPA2007-62833 Financiación: info:eu-repo/grantAgreement/ES/MICINN/FPA2008-03456 Tipo y forma: Article (Published version) Área (Departamento): Proy. investigación HCA (Dpto. Física Teórica) Área (Departamento): Área Física Atóm.Molec.y Nucl. (Dpto. Física Teórica)