INVESTIGATION OF INVERSE BETA-DECAY ON PROTONS AT THE UPGRADED DETECTOR DEUTERON

An experiment is proposed in which the cross section for the interacti on of reactor antineutrinos with deuterons is measured with the upgrad ed low-background detector Deuteron positioned near the Krasnoyarsk nu clear reactor. The features of the detector are presented. The backgro und and the detector efficiency are estimated with the aid of the MCU- RFFI codes developed for solving the neutron-transport equation and cr iticality problems for neutron-breeding systems. The calculated featur es of the detector are compared with experimental results. The cross s ection for inverse beta decay on a proton was measured by using the de tector filled with light water and positioned at a distance of 34.0 m from the reactor. The result of this measurement, sigma((v) over bar p expt) = (6.39 +/- 0.19) x 10(-43) cm(2) per event of U-235 fission, co rresponds to sigma(expt) = o(v - A) X (1.00 +/- 0.04) (at a 68% C.L.). On this basis, it has been found that, at a 90% C.L., the parameters of neutrino oscillations must satisfy the constraints Delta m(1,2)( 2) less than or equal to 0.016 eV(2) for sin(2)2 theta = 1 and sin(2)2 t heta less than or equal to 0.09 for Delta m(1,2)( 2) 1 eV(2). The cons traints on the neutrino-oscillation parameters from neutrino experimen ts at the Krasnoyarsk nuclear reactor are compared with those from oth er recent experiments and with those expected from experiments planned elsewhere.