Abstract
A search has been performed for neutrinos from two sources, the $hep$ reaction in the solar $pp$ fusion chain and the $\nu_e$ component of the diffuse supernova neutrino background (DSNB), using the full dataset of the Sudbury Neutrino Observatory with a total exposure of 2.47 kton-years after fiducialization. The $hep$ search is performed using both a single-bin counting analysis and a likelihood fit. We find a best-fit flux that is compatible with solar model predictions while remaining consistent with zero flux, and set a one-sided upper limit of $\Phi_{hep} < 30\times10^{3}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$ [90% credible interval (CI)]. No events are observed in the DSNB search region, and we set an improved upper bound on the $\nu_e$ component of the DSNB flux of $\Phi^\mathrm{DSNB}_{\nu_e} < 19~\textrm{cm}^{-2}~\textrm{s}^{-1}$ (90% CI) in the energy range $22.9 < E_\nu < 36.9$~MeV.
Highlights
Solar neutrinos produced in the pp fusion cycle have been studied extensively by several experiments [1,2,3,4,5,6]
These probability distribution function (PDF) are constructed from Monte Carlo events that have been modified according to a set of s systematic parameters Δ, with associated Gaussian uncertainties σΔ
In agreement with the counting analysis up to differences introduced by the statistical treatments, this result is compatible with the BSB05(GS98) model prediction and is consistent with zero hep flux
Summary
Solar neutrinos produced in the pp fusion cycle have been studied extensively by several experiments [1,2,3,4,5,6]. KPresent address: Department of Physics, University of Winnipeg, Winnipeg, Manitoba, Canada. RPresent address: Department of Physics and Astronomy, University of Kentucky, Lexington KY. SPresent address: Department of Physics and Astronomy, Rutgers University, Piscataway, NJ. ZPresent address: Department of Physics and Astronomy, University of Sussex, Brighton, UK. Expected in the energy range above the end point of the 8B solar neutrino spectrum is the diffuse supernova neutrino background (DSNB), the isotropic neutrino flux from past core-collapse supernovae [9,10]. The DSNB signal remains undetected, and the Sudbury Neutrino Observatory (SNO) experiment provides unique sensitivity to the νe component of the flux [15]. A previous search for the hep and DSNB neutrinos with the SNO detector used data from the first operating phase, 306.4 live days with a heavy water (D2O) target [16].
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