Electron Antineutrino Search at the Sudbury Neutrino Observatory

TL;DR

This paper reports on setting upper limits for electron antineutrino flux from the Sun using the Sudbury Neutrino Observatory, employing a distinctive detection signature and analyzing data across multiple energy ranges.

Contribution

The study introduces a low-background search method for solar electron antineutrinos using deuterium reactions at SNO, providing new flux limits and extending previous constraints.

Findings

Set upper limits on solar  flux in 4-14.8 MeV range

Achieved a flux limit of  <= 3.4 x 10^4 cm^{-2} s^{-1}

Compared results with KamLAND and previous experiments

Abstract

Upper limits on the \nuebar flux at the Sudbury Neutrino Observatory have been set based on the \nuebar charged-current reaction on deuterium. The reaction produces a positron and two neutrons in coincidence. This distinctive signature allows a search with very low background for \nuebar's from the Sun and other potential sources. Both differential and integral limits on the \nuebar flux have been placed in the energy range from 4 -- 14.8 MeV. For an energy-independent \nu_e --> \nuebar conversion mechanism, the integral limit on the flux of solar \nuebar's in the energy range from 4 -- 14.8 MeV is found to be \Phi_\nuebar <= 3.4 x 10^4 cm^{-2} s^{-1} (90% C.L.), which corresponds to 0.81% of the standard solar model 8B \nu_e flux of 5.05 x 10^6 cm^{-2} s^{-1}, and is consistent with the more sensitive limit from KamLAND in the 8.3 -- 14.8 MeV range of 3.7 x 10^2 cm^{-2} s^{-1} (90% C.L.). In the energy range from 4 -- 8 MeV, a search for \nuebar's is conducted using coincidences in which only the two neutrons are detected. Assuming a \nuebar spectrum for the neutron induced fission of naturally occurring elements, a flux limit of Phi_\nuebar <= 2.0 x 10^6 cm^{-2} s^{-1}(90% C.L.) is obtained.