Search for neutron-mirror neutron oscillations in a laboratory experiment with ultracold neutrons

Mirror matter is considered as a candidate for dark matter. In connection with this an experimental search for neutron-mirror neutron (nn') transitions has been carried out using storage of ultracold neutrons in a trap with different magnetic fields. As a result, a new limit for the neutron-mirror neutron oscillation time tau(osc) has been obtained, tau(osc) >= 448 s (90% C.L.), assuming that there is no mirror magnetic field larger than 100 nT. Besides a first attempt to obtain some restriction for mirror magnetic field has been done. (C) 2009 Elsevier B.V. All rights reserved.