Speaker
Michael Smy
(UCI)
Description
We present a strong indication that the elastic scattering rate of solar
$^8$B neutrinos with electrons in the Super-Kamiokande detector is larger
when the neutrinos pass through the earth during night time. We determine
the day/night asymmetry to be -3.2$\pm$1.1(stat)$\pm$0.5(syst)\% which deviates
from zero by 2.7$\sigma$. A non-zero Super-Kamiokande day/night
asymmetry implies that the flavor oscillations of solar neutrinos
are affected by the presence of matter within the neutrinos' flight path.
Super-Kamiokande's day/night asymmetry is consistent with neutrino
oscillations for $4\cdot10^{-5}$eV$^2\leq\Delta m^2_{21}\leq8\cdot10^{-4}$eV$^2$.
The recoil electron spectrum shape is consistent with no distortions due
to neutrino oscillation within 0.9$\sigma$. The impact of the measurements of the
average elastic scattering rate, the day/night asymmetry, and the recoil electron
spectrum shape is discussed.
Author
Michael Smy
(UCI)
