Search for neutrino oscillations at the Palo Verde nuclear reactors

We report on the initial results from a measurement of the antineutrino flux and spectrum at a distance of about 800 m from the three reactors of the Pale Verde Nuclear Generating Station using a segmented gadolinium-loaded scintillation detector. We find that the antineutrino flux agrees with that predicted in the absence of oscillations excluding at 90% C.L. <(nu)over bar>(e)-<(nu)over bar>(x) oscillations with Delta m(2) > 1.12 x 10(-3) eV(2) for maximal mixing and sin(2)2 theta > 0.21 for large Delta m(2). Our results support the conclusion that the atmospheric neutrino oscillations observed by Super-Kamiokande do not involve nu(e).