Antineutrino background from spent-fuel storage in sensitive searches for θ 13 at reactors

Sensitive searches for antineutrino oscillations in the atmospheric mass-parameter region much discussed in recent years are based on accurate comparison of the inverse-beta-decay positron spectra measured in two (or more) detectors, far and near, stationed, e.g., at about 1000 and about 100 m from the reactor(s). We show that antineutrinos emitted from the stored irradiated fuel can distort in a different way the soft part of positron spectra measured in the far and near detectors and thus mimic (or hide) the oscillation signal. The text was submitted by the authors in English.