Final results from the Palo Verde Neutrino Oscillation Experiment

TL;DR

This paper reports the final results from the Palo Verde Neutrino Oscillation Experiment, which measured antineutrino interactions at ~750-890 meters from reactors, finding no evidence for neutrino oscillations within the tested parameter space.

Contribution

The study provides comprehensive analysis and results from the complete data set, setting new limits on neutrino oscillation parameters and employing innovative background determination techniques.

Findings

No evidence for neutrino oscillation was observed.

Excluded certain oscillation modes at 90% confidence level.

Set limits on neutrino mass-squared differences and mixing angles.

Abstract

The analysis and results are presented from the complete data set recorded at Palo Verde between September 1998 and July 2000. In the experiment, the $\nuebar$ interaction rate has been measured at a distance of 750 and 890 m from the reactors of the Palo Verde Nuclear Generating Station for a total of 350 days, including 108 days with one of the three reactors off for refueling. Backgrounds were determined by (a) the $swap$ technique based on the difference between signal and background under reversal of the positron and neutron parts of the correlated event and (b) making use of the conventional reactor-on and reactor-off cycles. There is no evidence for neutrino oscillation and the mode $\nuebar\to\bar\nu_x$ was excluded at 90% CL for $\dm>1.1\times10^{-3}$ eV$^2$ at full mixing, and $\sinq>0.17$ at large $\dm$.