Altarev, I. Ban, G. Bison, Georg Bodek, K. Daum, M. Fertl, M. Fierlinger, P. Franke, B. Gutsmiedl, E. Heil, W. Henneck, R. Horras, M. Khomutov, N. Kirch, K. Kistryn, S. Kraft, A. Knecht, A. Knowles, Paul E. Kozela, A. Lauer, T. Lauss, B. Lefort, T. Lemière, Y. Mtchedlishvili, A. Naviliat-Cuncic, O. Pazgalev, Anatoly S. Petzoldt, G. Piegsa, F. M. Pierre, E. Pignol, G. Quéméner, G. Rebetez, M. Rebreyend, D. Roccia, S. Schmidt-Wellenburg, P. Severijns, N. Sobolev, Yu. Weis, Antoine Zejma, J. Zenner, J. Zsigmond, G. 2010-10-06 Physics at the Planck scale could be revealed by looking for tiny violations of fundamental symmetries in low energy experiments. In 2008, a sensitive test of the isotropy of the universe has been performed with stored ultracold neutrons (UCN), this is the first clock-comparison experiment performed with free neutrons. During several days we monitored the Larmor frequency of neutron spins in a weak magnetic field using the Ramsey resonance technique. A nonzero cosmic axial field, violating rotational symmetry, would induce a daily variation of the precession frequency. Our null result constitutes one of the most stringent tests of Lorentz invariance to date. application/pdf https://folia.unifr.ch/global/documents/302081 https://folia.unifr.ch/documents/302081/files/wei_tiu.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.physb.2010.09.044 info:eu-repo/semantics/openAccess License undefined Physica B: Condensed Matter. - 2011, vol. 406, no. 12, p. 2365-2369 info:eu-repo/classification/udc/53 Testing isotropy of the universe using the Ramsey resonance technique on ultracold neutron spins http://purl.org/coar/resource_type/c_6501